Brazilian developments on the

Regional Atmospheric Modeling System

BRAMS -‐ version 5.2

DESCRIPTION OF THE

MODEL INPUT NAMELIST PARAMETERS

S. R. Freitas, L. F. Rodrigues, J. Panetta, K. Longo, D. Moreira, E. Freitas,

M. Longo, A. Fazenda, R. Fonseca, R. Stockler, G. Camponogara

http://brams.cptec.inpe.br

Document Edition 1.0

March 2016

Updated document developed upon the previous versions

By • Robert L. Walko and Craig J. Tremback (RAMS).

• Jairo Panetta, Saulo R. Freitas, Alvaro L.Fazenda, Edmilson D. Freitas

and Eduardo H.Enari (BRAMS)

Table of Contents

Introduction .............................................................................................................................................. 3

BRAMS Version ...................................................................................................................................... 5

Model Configuration Parameters – Fortran 90 Module: “grid_dims.f90” ........ 6

Model Namelists .................................................................................................................................... 8

$MODEL_GRIDS Namelist ......................................................................................................... 8

$CCATT_INFO namelist ............................................................................................................. 25

$TEB_SPM_INFO namelist ...................................................................................................... 26

$MODEL_FILE_INFO Namelist .............................................................................................. 30

$MODEL_OPTIONS Namelist ................................................................................................. 48

$MODEL_SOUND Namelist ..................................................................................................... 67

$MODEL_PRINT Namelist ........................................................................................................ 69

RAMS ISAN Configuration Parameters – Fortran 90 Module: “isan_coms

.f90” .............................................................................................................................................................. 71

RAMS ISAN Namelists ..................................................................................................................... 72

$ISAN_ISENTROPIC Namelist - ISAN Isentropic/σz Stage ..................................... 74

Introduction

This document describes the input namelist parameters for the BRAMS v. 5.1

atmospheric model with recent developments. Specifying values for each of the

variables in the atmospheric model namelists is the main way that a user may

configure the model and select from the many options available for a particular

model run. The namelists RAMSIN in BRAMS 5.1 are standard FORTRAN namelists.

The atmospheric model component of BRAMS contains 5 namelists, namely:

• $MODEL_GRIDS

• $MODEL_FILE_INFO

• $MODEL_OPTIONS

• $MODEL_SOUND

• $MODEL_PRINT,

The atmospheric chemistry modules (CCATT and TEB-‐SPM) coupled to BRAMS are

described in 2 sections, one for each different model:

• $CCATT_INFO

• $TEB_SPM_INFO

while the initialization and boundary conditions ISAN namelist are:

• $ISAN_CONTROL

• $ISAN_ISENTROPIC.

Also new in this version, there are three additional namelists

$POST

$DIGITALFILTER

$METEOGRAM

These namelists are all contained in the data file called RAMSIN. This is a

default name; the input namelist name can be set as a command line argument. Each

namelist in this file begins with one of the above identifiers, and ends with the

character string “$END”. All variables in these namelists have sample values

assigned to them in the RAMSIN file, but the user will need to edit many of them for

a specific simulation or forecast. A sample RAMSIN file is available at ./BRAMS

directory.

The following sections contain descriptions of all atmospheric model parameters

and namelist variables. These descriptions include the meaning of each parameter

or variable and provide acceptable or recommended settings for them. Cross-‐

referencing to related variables provides additional information. For this reason, we

recommend a complete read-‐through of all namelist variables. An index of the

configuration and namelist variables can be found at the end of this document.

IMPORTANT: Note as a matter of syntax that each value assigned to any namelist

variable in the RAMSIN file must be followed by a comma.

Brief description of the BRAMS development

BRAMS was originally developed as part of a joint project between ATMET/USA and

the Brazilian institutions IME/USP, IAG/USP and CPTEC/INPE, and funded by FINEP

(Brazilian Funding Agency). This project aimed to produce a new version of the

Regional Atmospheric Modeling System (RAMS) tailored to address some of the

environmental problems of the tropics. The main objective was to provide a single

model for Brazilian regional weather and research centers.

The first version (BRAMS 1.0) was based on RAMS 5.0, with the inclusion of

modeling of physical phenomena such as Shallow Cumulus and New Deep

Convection (mass flux scheme with several closures, based on Grell et al., 2002),

improvements in software quality (leading to binary reproducibility with just 1 grid

and higher portability) and a higher resolution vegetation data file (1 km vegetation

data derived from IGBP 2.0 + IBGE/INPE dataset LEAF-‐3 with observed parameters

for South American biomes).

The version 2.0 was based on RAMS 5.04, and included all of modifications

described above and a new surface parameterization using SiB 2.5 submodel, a new

scheme to assimilate a heterogeneous Soil Moisture profile based on satellite data,

binary reproducibility with nested grids, corrections for Lite and Mean variables

output and improvements in software quality trough checking if all variables were

properly initialized.

The following stable version, named BRAMS 3.2, was the first distributed in CC-‐GNU

GPL in an official home-‐page (http://www.cptec.inpe.br/brams). It included the

version 2.0 plus enhanced portability and software quality, improvements on the

heterogeneous soil moisture assimilation procedure, an operational assimilation

cycle and forecast procedure and improvements in serial and parallel performance.

The version BRAMS 4.0 was an extension of the version 3.2, with enhancements in

portability (running in NEC SX-‐6 and others compilers) and software quality

(including new procedure to read RAMSIN. It also featured a new scheme to build

executable code, etc), improvements on serial and parallel performance (best

vectorization rates in some codes, improvements on performance for advection

scheme and improvements in master-‐slave communications), corrections in Shaved

ETA scheme and LEAF scheme based on RAMS 6.x, inclusion of a new scheme for

radiation (CARMA parameterization), inclusion of a new option to allow manual

domain decomposition and also include the option of 2 new emission model running

coupled to BRAMS: the CATT (Coupled Aerosol and Tracer Transport) scheme and

TEB-‐SPM (Town Energy Budget – Simple Photochemical Module) scheme.

The current version of the BRAMS (5.2 as in December, 2015) has several new

features described in the table below and illustrated by the figure 1.

BRAMS v. 5.1

Features

Advection

for Highly accurate and monotonic scheme (Walcek 2000, Freitas

scalars

et al. 2012)

Sub-‐grid

scale Grell and Deveny (2002) cumulus scheme – (deep / shallow)

convective transp. New Cumulus scheme (aerosol and scale aware – Grell and

and wet deposition Freitas 2014)

PBL Turbulence

Nakanishi & Nino (2004)

Dry deposition

Resistance approach coupled with surface and PBL schemes.

Emissions

MEGAN, EDGAR, RETRO, 3BEM, 3BEM-‐FRP (Pereira et al.,

2009), GFED, Volcanoes. Urban emissions inventory for SA

(Alonso et al., 2010).

Plume rise – Veg. 1-‐D in-‐line cloud model forced by the fire heat flux (Freitas et

Fires

al., 2007/2010)

Gas/Aqueous

SPACK pre-‐processor (RACM, RELACS, CB07, etc) with

Phase Chemistry

Rosenbrock 2nd and 3rd order solvers (Longo et al., 2013)

Photolysis

LUT, FAST-‐JX, FAST-‐TUV (in-‐line, aerosol and clouds effects)

Surface scheme

JULES with carbon cycle, biogenic VOCs (Moreira et al., 2013)

Radiation

CARMA (Longo et al., 2006, Rosário et al., 2013), RRTMG (LW,

SW)

Aerosols

Simple mono-‐disperse for biomass burning/urban sources

and the complex modal aerosol model “MATRIX” (Bauer et al

2008).

Aerosol direct / Included in radiation (CARMA, RRTMG), 2-‐moments cloud

indirect effects

microphysics (RAMS and GT) and cumulus scheme (GF).

Microphysics

• Double moment from RAMS 6.0 CSU version

• Single moment in cloud liquid water from G. Thompson

(NCAR)

• Double moment in cloud liquid water and aerosol aware

from G. Thompson (NCAR).

Computational

Efficiency at 103 -‐ 104 cores (MPI)

scalability

Lagrangian

Output to drive the STILT Lagrangian particle model.

Particle Model

BRAMS 5

Figure 1. Several sub-‐grid scale physical and chemical processes simulated by the

BRAMS v. 5.1+ model.

Some of the basic references for BRAMS 5.2 are described below:

1. Bela, M. M., Longo, K. M., Freitas, S. R., et al.: Ozone production and transport over

the Amazon Basin during the dry-to-wet and wet-to-dry transition seasons, Atmos.

Chem. Phys., 15, 757, 2015.

2. Grell, G. A., and S.R. Freitas: A scale and aerosol aware stochastic convective

parameterization for weather and air quality modeling. Atmos. Chem. Phys., 14,

5233, 2014.

3. dos Santos, A. F., Freitas, S. R., de Mattos, J. G. Z., et al.: Using the Firefly

optimization method to weight an ensemble of rainfall forecasts from the Brazilian

developments on the Regional Atmospheric Modeling System (BRAMS). Adv.

Geosci., 35, 123, 2013.

4. Moreira, D., Freitas, S. R., Bonatti, J. P., et al.: Coupling between the JULES land-

surface scheme and the CCATT-BRAMS atmospheric chemistry model: applications

to numerical weather forecasting and the CO2 budget in South America. Geos.

Model Devel., 6, 1243, 2013.

5. Longo, K. M., Freitas, S. R., Pirre, M., et al.: The chemistry CATT-BRAMS model

(CCATT-BRAMS 4.5): a regional atmospheric model system for integrated air

quality and weather forecasting and research. Geos. Model Devel., 6, 1389, 2013.

6. Rosário, N. E., Longo, K. M., Freitas, S. R., et al.: Modeling South America regional

smoke plume: aerosol optical depth variability and shortwave surface forcing.

Atmos. Chem. Phys. 13, 2923, 2013.

7. Freitas, S.R., L.F. Rodrigues, K.M. Longo, J. Panetta: Impact of a monotonic

advection scheme with low numerical diffusion on transport modeling of emissions

from biomass burning. Journal of Advances in Modeling Earth Systems, 4, M01001,

2012.

8. Freitas, S. R., Longo, K. M., Alonso, M. F. et al.: PREP-CHEM-SRC 1.0: a

preprocessor of trace gas and aerosol emission fields for regional and global

atmospheric chemistry models. Geosci. Model Devel., 4, 419, 2011.

9. Freitas, S. R., Longo, K., Trentmann, J., Latham, D.: Technical Note: Sensitivity of

1D smoke plume rise models to the inclusion of environmental wind drag. Atmos.

Chem. Phys., 10, 585, 2010.

10. Longo, K. M., Freitas, S. R., Andreae, M. O., et al.: The Coupled Aerosol and Tracer

Transport model to the Brazilian developments on the Regional Atmospheric

Modeling System (CATT-BRAMS) Part 2: Model sensitivity to the biomass burning

inventories. Atmos. Chem. Phys., 10, 5785, 2010.

11. Alonso, M. F., Longo, K. M., Freitas, S. R., et al.: An urban emissions inventory for

South America and its application in numerical modeling of atmospheric chemical

composition at local and regional scales. Atmospheric Environment, 44, 5072, 2010.

12. Pereira, G., Freitas, S. R., Moraes, E. C. et al.: Estimating trace gas and aerosol

emissions over South America: Relationship between fire radiative energy released

and aerosol optical depth observations. Atmospheric Environment, 43, 6388, 2009.

13. Freitas, S. R., Longo, K. M., Silva Dias, M. A. F., et al.: The Coupled Aerosol and

Tracer Transport model to the Brazilian developments on the Regional Atmospheric

Modeling System (CATT-BRAMS) – Part 1: Model description and evaluation,

Atmos. Chem. Phys., 9, 2843, 2009.

14. Freitas, S. R., K. M. Longo, R. Chatfield, et al.: Including the sub-grid scale plume

rise of vegetation fires in low resolution atmospheric transport models. Atmos.

Chem. Phys., 7, 3385 2007.

15. Freitas, E. D.; Rozoff, C. M.; Cotton, W. R. et al: Interactions of an urban heat island

and sea breeze circulations during winter over the Metropolitan Area of São Paulo -

Brazil. Boundary - Layer Meteorology, v. 122(1), p. 43-65, 2007.

16. Freitas, S. R., K. M. Longo, M. Silva Dias, et al.: Monitoring the transport of

biomass burning emissions in South America. Environmental Fluid Mechanics, 5,

135, 2005.

17. Nakanishi, M., H. Niino: An improved Mellor-Yamada Level-3 Model with

condensation physics: its design and verification. Boundary-Layer Meteorol. 112, 1-

31, 2004.

18. Miller, S. M, D. M. Matross, A. E. Andrews, et al.: Sources of carbon monoxide and

formaldehyde in North America determined from high-resolution atmospheric data.

Atmos. Chem. Phys. 8, 7673-7696, 2008.

19. Medvigy, D., P. R. Moorcroft, R. Avissar, R. L. Walko: Mass conservation and

atmospheric dynamics in the Regional Atmospheric Modeling System (RAMS).

Environ. Fluid Mech., 5, 109-134, 2005.

20. Souza, E. P., Rennó, N. O., Dias, M. A. F. S.: Convective circulations induced by

surface heterogeneities. Journal of the Atmospheric Sciences, v. 57, n.17, p. 2915-

2922, 2000.

Model Configuration Parameters – Fortran 90 Module:

“grid_dims.f90”

There

are

11

parameters

in

the

“grid_dims.f90” file (found at

<BRAMS_ROOT_DIRECTORY>/src/brams/modules/), 9 of them are used as

array dimensions for many variables in the in the atmospheric model global

memory and 2 of then are used to set array dimensions exclusive to coupled TEB

emission model. Whenever any of these parameters is changed, the entire model

code must be recompiled, according to dependencies described in the build

structure. These parameters set limits on maximum numbers of grid points, grids,

etc. Normally, model simulations should run with the default dimensions,

however, for very large simulations, one may need to increase these parameters.

The parameters should be set large enough for the required model space, and

for convenience, large enough to fit any anticipated expansions of required model

space, but not so large that excessive computer memory is unnecessarily

allocated. Most significant memory space is now dynamically allocated, so these

parameters are not as important in determining memory usage as in the past.

The grid_dims.f90 parameters are described in the following table.

MAXGRDS The maximum number of grids that may be used in a model run. The

integer

number of grids actually used in a run is specified by the namelist

variable NGRIDS. NGRIDS may be changed from one model run to the

next using

the same executable, as long as NGRIDS does not exceed the value of

MAXGRDS that was set when compiling the model. Thus, MAXGRDS

should be set to the largest number of grids that will be used in a series

of runs made from the same compiled code.

NXPMAX

The maximum number of grid points in the x-direction to be used on any

integer

grid.

The

actual numbers of grid points spanning the x-direction on

individual grids are specified in the multiple values of the namelist variable

NNXP. NXPMAX must be equal to or larger than each of the NNXP values.

NYPMAX

The maximum number of grid points in the y-direction to be used on any

integer

grid.

The

actual numbers of grid points spanning the y-direction on

individual grids are specified in the multiple values of the namelist variable

NNYP. NYPMAX must be equal to or larger than each of the NNYP values.

NZPMAX

The maximum number of grid points in the z-direction to be used on any

integer

grid.

The

actual numbers of grid points spanning the z-direction on

individual grids are specified in the multiple values of the namelist variable

NNZP. NZPMAX must be equal to or larger than each of the NNZP values.

NZGMAX

The maximum number of vertical levels to be used on any grid in the soil

integer

model. The actual numbers of levels on individual grids are specified in the

namelist variable NZG. NZGMAX must be equal to or larger than NZG.

MAXSCLR

The maximum number of scalars that may be automatically added to a

integer

simulation.

The actual number of added scalars is specified in namelist

parameter NADDSC. MAXSCLR must be equal to or larger than NADDSC.

MAXDIM

MAXDIM must be set to the largest of the values in NXPMAX, NYPMAX,

integer

NZPMAX+10, and NZGMAX.

MAXMACH

The maximum number of nodes that may be used for a parallel model run.

integer

Applies only to running the model in parallel processing mode using MPI.

VARIABLES EXCLUSIVE FOR THE COUPLED TEB EMISSION MODEL

MAXSTEB

Set the maximum number of layers used in TEB.

MAXUBTP

Set the maximum number of urban types used in TEB.

Model Namelists

The following sections will describe the input namelist parameters for the BRAMS

and RAMS atmospheric model, the coupled CCATT and TEB-SPM chemistry models and the RAMS/ISAN (ISentropic ANalysis) package.

Specifying values for each of the variables in the atmospheric model namelists is the

principal way that a user sets up the desired model configuration and selects the

many options available for a particular model run. The namelists is a standard

FORTRAN namelist.

The atmospheric model component of BRAMS/RAMS namelist contains 5 sections,

which

have

the

names

$MODEL_GRIDS,

$MODEL_FILE_INFO,

$MODEL_OPTIONS, $MODEL_SOUND, and $MODEL_PRINT, for the emission

models coupled to the atmospheric model BRAMS (CCATT and TEB-SPM), the

namelist are: $CCATT_INFO and $TEB_SPM_INFO, while the ISAN namelist are

called $ISAN_CONTROL, and $ISAN_ISENTROPIC. These namelists are all

contained in the data file called RAMSIN. This is a default name; the input namelist

name can be set as a command line argument. Each section of namelist in this file

begins with one of the above identifiers, and ends with the character string “$END”.

All variables in these namelists have sample values assigned to them in the RAMSIN

file, but the user will need to edit many of them for a specific simulation or forecast. In

this version 5.1 of BRAMS, is not possible to run both chemistry models (CCATT and

TEB-SPM) at the same time. This feature is planed to be available only in future

versions.

$MODEL_GRIDS Namelist

The $MODEL_GRIDS namelist provides information to the model primarily on the

structure of the one or more nested grids used in a simulation, including location,

mesh size, number of mesh points, spatial nesting relationships, time step length, and

time and duration of the run. Most of these variables are arrays dimensioned to the

parameter MAXGRDS, which is set in the file grid_dims.f90. Each value in the array

applies to a different grid, several of which may be activated if the user wishes to

employ grid nesting. In the $MODEL_GRIDS and other namelists, the multiple values

are separated by commas following the variable name and an equals sign. The

RAMSIN file must have at least as many values of the grid-dependent variables

specified as the value assigned to NGRIDS, but no more than the value of

MAXGRDS. Values in the NAMELIST corresponding to grid number greater than

NGRIDS are ignored by the model.

Variable

Description

Name /

FORTRAN

type

EXPNME

Character string of up to 64 characters into which the user may put any message (i.e.,

character

the experiment name) identifying the particular simulation or run. The character string

is written in the standard output listing file and simply serves as a convenient means of

labeling the output for the user's own purposes.

RUNTYPE

Variable specifying one of six ways in which the model is to be run.

character

In many situations, a RUNTYPE = 'MAKESFC' should be the first run that is made.

This type of run will start the model and create surface characteristic datasets for all

grids that will be used during subsequent runs. These characteristics include

topography, soil textural class, sea surface temperature, vegetation class, and subgrid

distribution of soil textural class, water surface, and vegetation type, all of which are

available in standard RAMS global datasets from which they can be interpolated onto

each model grid. These characteristics will be initialized on the model grids according

to the specifications of ITOPTFLG, ISSTFLG, IVEGTFLG, ISOILFLG, and NDVIFLG,

then surface files, one for each grid, be created with a filename prefix specified by the

variable SFCFILES, and SST files, one for each grid and for each SST data time

available, will be created with a filename prefix specified by the variable SSTFPFX.

These files can then be quickly re-read on subsequent runs of the model or ISAN. An

important benefit of the ‘MAKESFC’ option is that topography for all grids can

bedefined with a fine grid present, and the fine grid can then be excluded for the first

part of the simulation, to be added later on a history restart. This allows the model to

utilize topography on its coarser grids that will be consistent with the future addition of

the fine grid.

If RUNTYPE is ‘MAKESFC’, the model run will stop immediately after the appropriate

files are generated and will not proceed with integration.

A value of 'MAKEVFILE' is the choice that runs ISAN which performs an objective

analysis of one or more observational datasets, and produces one or more resultant

variable initialization files, or ‘varfiles’. The varfiles contain a set of atmospheric fields

defined on the model grids configured as specified by other variables in the

$MODEL_GRIDS namelist, and are to be used in a later run for initializing a

simulation, and optionally as 4-D assimilation data during the course of the simulation.

The MAKEVFILE option is used only if the model is to be initialized from a complete 3-

D objective analysis, (the INITIAL variable in the $MODEL_GRIDS namelist set to 2),

and is the means by which the observational data are processed and interpolated to

the model grid(s). The most common way to use this option is to generate varfiles from

the objective analysis package every 12 hours, since that is the time interval at which

upper-air data are normally collected, or every 6 hours to correspond with the NCEP

reanalysis data times. The total number of varfiles required depends on the duration of

the simulation to be performed and the particular grids which will be initialized from

them (and optionally will use them for 4DDA). The first varfile must correspond to the

starting time of the simulation, while the last varfile must equal to or later than the end

of the simulation.

If RUNTYPE is set to 'INITIAL', the current model run is designated to be the first of a

simulation (see definitions of run and simulation in the entry for TIMMAX below). This

means that a simulation is begun at time zero, and that all atmospheric and soil

prognostic variables are initialized either horizontally homogeneously from sounding

and soil data in the $MODEL_SOUND and $MODEL_OPTIONS namelists (INITIAL=1

in this case), read from a varfile prepared in an earlier ISAN run (INITIAL=2), or

interpolated from a previous RAMS history file (INITIAL=3).

If RUNTYPE is set to 'HISTORY', the model is to be history restarted, meaning that

the atmospheric and soil prognostic variables are read from a history file, which was

written by the model on a previous run. This option is used when a simulation is

carried out over a series of two or more runs. (Also see IOUTPUT and HFILOUT.)

TIMEUNIT

Time units in which the variables TIMMAX and TIMSTR are expressed. The

character

allowable values of TIMEUNIT are:

's' to denote 'seconds',

'm' to denote 'minutes',

'h' to denote 'hours',

‘d’ to denote ‘days’.

This option allows numerical values for the above variables to be specified within

convenient ranges for any simulation, which may range in duration from seconds to

years.

TIMMAX

Time during a simulation in units of seconds, minutes, or hours (see TIMEUNIT)

real

when the current run is to stop. It is important to distinguish the terms simulation

and run. A simulation is the entire integration of the atmospheric model from the initial

state to the final time. It consists of one or more runs, which are individual

submissions of the model code to the computer for execution. The TIMMAX

variable represents the total time elapsed from the beginning of an entire simulation,

starting with the first run, and is cumulative over successive runs. However, it

denotes the time at which the current run is to terminate, rather than when the entire

simulation is to end. (also see TIMSTR.) If RUNTYPE is set to ‘MAKEVFILE’ in

order to run ISAN, TIMMAX specifies the duration of the time period over which

to process observational data and generate varfiles.

LOAD_BAL

flag activating a dynamic load balance in a parallel run. This was an experimental

capability and currently deprecated. The default value of zero must not be changed.

integer

IMONTH1

Month of the year when the simulation begins. It is used in conjunction with the

integer

namelist parameters IYEAR1, IDATE1 and ITIME1 to determine the proper solar

declination angle for a simulation and to coordinate the model clock with dates and

times of various observational datasets and vegetation seasonal cycles.If

RUNTYPE is set to ‘MAKEVFILE’ in order to run ISAN, IMONTH1 specifies the

month of the beginning of the time period over which to process observational data

and generate varfiles.

Date of the month when the simulation begins. It is used in conjunction with the

namelist parameters IYEAR1, IMONTH1 and ITIME1 to determine the proper

IDATE1

solar declination angle for a simulation and to coordinate the model clock with dates

integer

and times of various observational datasets and vegetation seasonal cycles. If

RUNTYPE is set to ‘MAKEVFILE’ in order to run ISAN, IDATE1 specifies the

date of the beginning of the time period over which to process observational data

and generate varfiles.

IYEAR1

Year when the simulation begins. It serves as an identifier of the simulation, along

integer

with IMONTH1, IDATE1, and ITIME1 to coordinate the model clock with dates

and times of various observational datasets. A 4-digit year must be specified for

IYEAR1. If RUNTYPE is set to ‘MAKEVFILE’ in order to run ISAN, IYEAR1

specifies the year of the beginning of the time period over which to process

observational data and generate varfiles.

ITIME1

Coordinated Universal Time (UTC) (or GMT) in hours and minutes (syntax is hhmm)

integer

when a model simulation begins (see definition of simulation in the description of

TIMMAX). This parameter is used in conjunction with the namelist parameters IYEAR1,

IMONTH1, and IDATE1 to determine the proper solar declination angle for a simulation

and to coordinate the model clock with dates and times of various observational datasets and

vegetation seasonal cycles. If RUNTYPE is set to ‘MAKEVFILE’ in order to run ISAN,

IMONTH1 specifies the month of the beginning of the time period over which to process

observational data and generate varfiles.

NGRIDS

Specifies the number of grids to be activated for the model run. If set to 1, only a single

integer

grid covering the entire spatial domain of the simulation will be activated. A setting of 2

will activate a nested grid within the first grid. A nested grid is used to attain a higher

spatial resolution in a limited area of the simulation domain. This finer-resolution second

grid communicates with the coarser-resolution parent grid via two-way interaction

following the scheme designed by Clark and Farley [1] and Walko et al. [2]. Figure 1

shows an example of a lattice consisting of two small nested grids. The example is a

horizontal cross section showing the relative positions of the horizontal velocity

components (u, v) and the thermodynamic variables (at locations denoted by t) according

to the Arakawa-C grid stagger used in RAMS. Upper-case letters denotes values on the

coarse grid, while those on the fine grid are indicated in lower-case letters. NGRIDS can

be set to as many nested grids as desired. However, the variable MAXGRDS must be set to

a value at least as large as NGRIDS. It is recommended that NGRIDS be set to 1 the first

time a simulation is begun, in order to test, at the relatively low cost incurred by the single

grid, the remainder of the model configuration specified by the other namelist variables

and other data inputs for the particular application. Once these tests are completed,

standard procedure is to add finer grids when necessary in regions where higher resolution

is desired, such as over complex terrain, or when trying to resolve a particular

meteorological feature such as a sea-breeze circulation or a thunderstorm. It is common for

a given simulation to consist of a series of sequential runs, each new run advancing the

simulation forward in time beyond the previous run. RAMS allows the user to increase the

value of NGRIDS from one run to the next (on a history restart), thus spawning new fine

grids during the course of the simulation, or to decrease NGRIDS to remove one or more

grids for the next run. It must be remembered that the variable MAXGRDS, needs to be set

to at least to at least the maximum value of NGRIDS which will be used at any time during

the simulation.

Important: in BRAMS 5.x ONLY one grid is allowed. Working is in progress to restore the

two-way nested grids capabilities of the previous versions.

NNXP

Number of grid cells to span the computational domain in the x-direction.

It is an

integer array

array dimensioned to MAXGRDS, and has a value for each grid activated. These

values are written in a single line in the namelist and are separated by commas. The

first value in the line refers to grid number 1, the second to grid 2, and so on. The

number of grid cells spanning each spatial direction (x,y,z) consists of interior cells

where normal evaluation of all terms (such as advective tendencies) in the governing

equations is performed, plus a boundary point at each end where variables are

computed only by boundary conditions based on interior values. In the example of

Figure 1, NXP (which is NNXP for grid 1) is set to 8, and the first and last grid cells

in the x-direction (index values I = 1 and I = 8) are the boundary points. Thus, the

actual computational domain may be considered to comprise only the interior cells,

those shown bounded by lattice lines in the figure, and the user may wish to set

NNXP to a value 2 larger than the intended domain size. For the U velocity points,

boundary conditions are applied at I = 1 and I = 7, with normal evaluation of the

governing equations being performed at points in between. The U values at I = 8 are

dummy points and are never used. The fine grid in Figure 1 also has nxp (which is

NNXP for grid 2) equal to 8. (Also see NSTRATX and NINEST). When RAMS is

run on a global domain, values of NNXP and NNYP must be equal to each other on

each hemispheric coarse grid and also equal between the two hemispheric coarse

grids.

NNYP

Similar to NNXP, but applies to the y-direction. The example in Figure 1 has NYP

integer array

(NNYP for the coarse grid) equal to 9 and nyp (NNYP for the fine grid) equal to 6.

If NNYP is set to 1, the simulation is two-dimensional, and NNYP must then also

be set to 1 for all grids activated. A two-dimensional simulation may not be done

with NNXP equal to 1 and NNYP greater than 1, i.e., only x-z cross sections can be

used for 2-D runs. However, the x-direction need not be aligned with geographic

east, but may represent any compass direction with minor changes to the code or

unusual placement of the polar stereographic pole point. Pseudo-one-dimensional

simulations may be configured by setting NNYP to 1 and NNXP to 5 coupled with

cyclic boundary conditions in the x-direction (see IBND). For the example in

Figure 1, boundary conditions are applied to T and U at J = 1 and J = 9, and to V at

J = 1 and J = 8. V at J = 9 is a dummy value and is never used. When RAMS is run

on a global domain, values of NNXP and NNYP must be equal to each other on

each hemispheric coarse grid and also equal between the two hemispheric coarse

grids.

NNZP

Similar to NNXP, but applies to the z-direction. Figure 2 shows an x-z cross section

integer array

through the model grid analogous to the x-y cross section of Figure 1.

Vertical

indices for the coarse and fine grids are K and k, respectively, and NZP and nzp

(which are the NNZP values for grids 1 and 2, respectively) are the corresponding

upper limits of these indices. Vertical velocity components are W and w. The

example consists of 7 interior grid cell levels on the coarse grid (K = 2 to K = 8 of T

cells) with boundary cells K = 1 below and K = 9 above. The ground surface is

located at the K = 1 W level, while the model top is considered to be at the K = 8 W

level. It is at this top level where W is set to 0 for the rigid lid model top boundary

condition. W at K = 9 is a dummy point and is never used. If the LEAF2 submodel

is activated in RAMS, NNZP must be at least NZG+NZS+3, and NZG+NZS must be at least 8. When RAMS is run on a global domain, values of NNZP must be

identical between grid 1 and the other hemispheric coarse grid.

NZG

Number of soil layers to be used in LEAF-3, a submodel of RAMS that prognoses

integer

energy and moisture in soil, snowcover, vegetation, and canopy air. The soil model

consists of a grid representing finite volumes in the uppermost meter or two of the

ground. Soil temperature and moisture are prognosed on this grid based on

equations governing their internal transport and external exchange with the

atmosphere. The horizontal dimensions and resolution of the soil model are

identical with those of the atmospheric model grid above, with NNXP and NNYP

applying equally to both models. NZG can be set to around 10 for most

applications, and NZG+NZS must be at least 8 if LEAF-3 is used.

NZS

Maximum number of snowpack layers allowed to occur in a simulation. It is

integer

relevant only when the LEAF-3 submodel is activated.

In RAMS, NZS must be at least 1, and has no upper limit other than a practical one.

If snow is not expected in a simulation, there is no need for NZS to be greater

than 1; in this case the layer will represent water ponding. If snowcover will occur, and

if its evolution is of some importance to the

simulation, a value around 5 is suggested for NZS in order to allow multiple snow

layers when snowcover is sufficiently deep. NZG+NZS must be at least 8

NXTNEST

Identifies the parent grid of each nested grid, i.e. , the coarser grid with which the

integer array

nested grid has direct communication. Defining values in this array is necessary

because different options are available for specifying the interrelation between grids.

The rule must always be followed that all grids from 1 up to NGRIDS are numbered

consecutively with no integers being skipped, and the coarser grid in which a finer

grid is nested always has a lower grid number than that finer grid. We consider first

the most common case where the RAMS domain is of limited area, covering no

more than about a hemisphere of the earth. For this case, the above rule implies that

grid 1 is always the coarsest grid, covering the entire computational domain, and

grid 2 is always nested directly within grid 1. Thus, NXTNEST for grid 2 (the

second value for NXTNEST) must always be set to 1. However, grid 3 can either

be nested in grid 1 (by setting NXTNEST for grid 3 equal to 1), meaning that it is at

an equal nesting level alongside grid 2, or grid 3 can be nested within grid 2 (by

setting NXTNEST for grid 3 equal to 2), such that it is two nesting levels finer than

grid 1. NXTNEST must be set to zero for any grid having no parent: Grid 1 never

has a parent, and for a limited area domain, it is the only grid without a parent.

DOMAIN_

File name that contains parallel decomposition of all grids, overwriting default

FNAME

BRAMS domain decomposition. Default domain decomposition is used if empty

character

DOMAIN_FNAME, or if pointed file does not exist or if it exists but its contents

are inconsistent with grid dimensions and number of processors. If file resides at the

same directory as the executable, it suffices to inform file name. If at any other

directory, it is required to inform file’s full path. File should be ASCII, with as many

lines as there are subdomains (one line for each slave process at each grid). Sub-

domains and grids may be informed at any order, but the set of lines should partition

all grids. Each line must contain the following six integers (in free- form format):

grid number (from 1 to NGRIDS), node number (from 1 to number of slave

processes), xbeg, xend, ybeg, yend. Example using 2 grids and 16 slaves nodes:

1

1

2

23

2

18

1

2

24

46

2

18

1

3

47

68

2

18

1

4

69

90

2

18

1

5

2

23

19

35

1

6

24

46

19

35

1

7

47

68

19

35

1

8

69

90

19

35

1

9

2

23

36

52

1

10

24

46

36

52

1

11

47

68

36

52

1

12

69

90

36

52

1

13

2

23

53

69

1

14

24

46

53

69

1

15

47

68

53

69

1

16

69

90

53

69

2

1

2

26

2

38

2

2

27

52

2

38

2

3

53

77

2

38

2

4

78

102

2

38

2

5

103

128

2

38

2

6

129

153

2

38

2

7

2

31

39

70

2

8

32

62

39

70

2

9

63

92

39

70

2

10

93

123

39

70

2

11

124

153

39

70

2

12

2

31

71

101

2

13

32

62

71

101

2

14

63

92

71

101

2

15

93

123

71

101

2

16

124

153

71

101

IF_ADAP

Flag to choose the vertical coordinate system.

integer

IF_ADAP=0: terrain-following sigma_z coordinate is used.

IF_ADAP=1: the ADaptive APerture coordinate is used. The ADAP coordinate is a

fully Cartesian grid where the grid cells intersect the topography. ADAP coordinate

allows partial grid cells along the topography.

Important: in BRAMS 5.x ONLY IF_ADAP = 0 is well tested and recommended.

Also, the CCATT module and the output for STILT particle model are currently

implemented only for IF_ADAP = 0

IHTRAN

Type of horizontal grid transformation to be used in a model simulation.

integer

IHTRAN=0: model grid will be Cartesian, with uniform horizontal spacing used

throughout the domain. This option is often used in small computational domains,

or where the simulation is of an idealized situation, not corresponding to any

particular geographic location. The basic assumption of this grid is that earth

curvature effects are negligible.

IHTRAN=1: sets up a polar stereographic coordinate system for the simulation.

While the model grid spacing itself appears uniform and Cartesian, map factors are

activated which cause the earth distances mapped from model distances to be of

variable resolution. A polar stereographic projection is a mapping between the

spherical earth and a plane (assumed to correspond to zero elevation in the Cartesian

model grid) tangent to the earth, with all projection lines emanating from the point

on the earth's surface opposite or antipodal to the point of tangency. The Cartesian

model plane is centered around the point of tangency, which may be placed

anywhere on the earth (the pole in this case refers to the point of tangency, specified

in namelist variables POLELAT and POLELON, not to either geographic pole).

Thus, size ratio in the center of the model domain is unity between the model grid

and the earth, and slowly increases outward toward the model lateral boundaries.

This transformation allows a single model grid to cover geographic domains up to

hemispheric in size, and avoids the numerical problems encountered near the

geographic poles when latitude-longitude coordinates are used.

DELTAX

Horizontal grid spacing or grid cell size in the x-direction of the model coarse grid

real

(grid 1) in units of meters. This very important parameter determines the scale of

meteorological features that are resolvable on the grid, and together with the number

of grid cells in the x-direction, NNXP, determines the total x-direction span of the

model domain. All spacings on the finer nested grids are derived from this value of

DELTAX along with the individual grid spacing ratios NSTRATX. In choosing

DELTAX for a simulation, the user needs to carefully consider, among other things,

what essential meteorological phenomenon is to be modeled, what the required

resolution is for adequately simulating this phenomenon, how large a domain is

required to contain the environment of the phenomenon, what the duration of the

simulation will be, whether nested grids will be used, and how much computer

memory and CPU time are available.

DELTAY

Similar to DELTAX, but specifies the y-coordinate, rather than x-coordinate

real

dimension of a grid cell on the model coarse grid. One should set DELTAX and

DELTAY to the same value, since different values may numerically force

horizontal anisotropy in the simulated fields. DELTAY should still be set equal to

DELTAX even in a 2D run.

DELTAZ

Similar to DELTAX, but specifies the vertical, rather than x-coordinate, dimension

real

of a grid cell on the model coarse grid. To be more precise, DELTAZ is the vertical

grid spacing of the lowest level of the coarsest model grid (grid 1), and is equal to

the vertical grid spacing at higher levels only if constant grid spacing is used in the

vertical. (Also see DZRAT and DZMAX.) However, if DELTAZ is set to 0., it

serves as a flag to instruct the model to read the ZZ variable from the namelist for

obtaining vertical grid levels directly. As for the case of DELTAX, selecting an

optimal value for DELTAZ involves a number of considerations. An additional

consideration in this case is that a small value for DELTAZ in a domain containing

steeply-sloping topography requires high horizontal resolution for computational

stability. A rule of thumb here is that the terrain height difference between adjacent

grid cells should not exceed about 3-5 times DELTAZ. If RAMS is run on a global

domain, the second hemispheric coarse grid automatically has the same vertical grid

spacing at all levels as grid 1.

DZRAT

Used in conjunction with DELTAZ, and specifies the ratio in vertical grid cell

real

dimension between adjacent levels on the coarse grid. DZRAT is used as a

convenient means for vertically stretching the grid, which is a very common practice

to obtain high vertical resolution near the ground and lower resolution at higher

levels.This method establishes a geometrically-stretched grid, wherein the

expansion ratio is constant between consecutive levels. Geometric stretching

minimizes the maximum expansion ratio between consecutive levels for a given net

stretching over a given number of vertical levels. It is desirable to keep the ratio

between consecutive levels small, as large ratios destroy the second-order accuracy

of the vertical differencing in the model. Values for DZRAT of 1.1 or even 1.2 are

considered acceptable. To illustrate with an example, if DELTAZ is set to 100 and

DZRAT is set to 1.1, the first (lowest) grid level will be 100 m thick, the next 1.1

times the first or 110 m, the third 1.1 times the second or 121 m, etc.

DZMAX

Upper bound on vertical grid spacing anywhere in the model coarse grid, and is used

real

in conjunction with DZRAX to prevent the automatic geometric grid stretching

from causing overly large vertical grid cell sizes in the upper levels of the model.

For example, if DZRAT is set to 1.1, the vertical grid spacing will increase by an

order of magnitude over 25 levels. This means that if the first level above the

surface is 200 m thick, the 26th level will be over 2 km thick. By specifying

DZMAX to a number such as 1000, the geometric expansion will halt when the

1000 m vertical thickness is reached, and all levels above will be made 1000 m

thick.

ZZ

Heights of coarsest grid levels in meters, beginning at the ground (ZZ = 0) and

real array

continuing to the top level in the model. The number of values specified for ZZ

must equal NNZP for grid 1, which is specified in the $MODEL_GRIDS namelist.

Specifying ZZ directly instead of using DELTAZ, DZRAT, and DZMAX is an

alternative means of setting the vertical grid structure, and of course offers more

flexibility because ZZ can be specified in many ways other than constant or

geometrically expanded spacing. However, when using direct specification via ZZ,

care needs to be taken not to cause two consecutive levels to have grossly different

vertical thicknesses, such as a factor of 2, as this degrades the accuracy of the

model's vertical differencing schemes. For the model to use the specified ZZ

values, DELTAZ must be set to 0.

IDELTAT

Flag that controls how RAMS obtains values of DTLONG, NNDTRAT, and

integer

NACOUST. If IDELTAT = 0, values specified in the $GRIDS namelist are used

and held fixed in time. If IDELTAT = 1, 2, 3, 4, or 5, RAMS will automatically

compute values for DTLONG, NNDTRAT, and NACOUST based on grid

spacings of all grids, model domain height, and other factors, and will hold these

values constant in time. IDELTAT = 1 produces the longest, riskiest timesteps that

experience has shown will still lead to stable model runs most of the time.

IDELTAT = 2 produces somewhat shorter, safer timesteps that cause instability in

even fewer cases, and higher values for IDELTAT cause progressively shorter long

timesteps to be used. These larger values would be appropriate if it is expected that

wind speeds on the grid will be relatively large. Since these parameters collectively

determine the long and short timesteps on all grids, and hence the computational

stability, if the CFL stability limit is exceeded and RAMS is instructed to keep

DTLONG, NNDTRAT, and NACOUST fixed, the model will stop and output a

CFL message. If IDELTAT = -1, -2, -3, -4, or –5, RAMS will compute initial values for DTLONG, NNDTRAT, and NACOUST as for IDELTAT = 1, 2, 3, 4,

or 5, respectively. Additional constraints based on CFL criterion will be applied,

both initially and during the model run, adjusting DTLONG, NNDTRAT, and

NACOUST to more stable values when necessary and to less stable values when the

model solution is well within the CFL limits. However, timesteps on individual

grids will not be adjusted to longer, less stable values than specified by the

IDELTAT flag. For example, if IDELTAT is set to –2, and the CFL criterion

requires adjustment to smaller timesteps but subsequently allows the timestep to be

lengthened, the timestep will not be lengthened beyond the values that correspond to

IDELTAT = 2. If the CFL limit requires timesteps to become shorter than values

that would correspond to IDELTAT = 5, the model will stop and output a CFL

message.

DTLONG

Length of the timestep in seconds at which most processes on the coarse grid will be

Real

updated. This is the primary timestep in the model to which all others relate. For

example, the values set for NNDTRAT, set integer ratios of timesteps between the

coarse and fine grids, such that an appropriate fraction of DTLONG is the actual

timestep used on a fine grid. One should set DTLONG reasonably close to, but below

the limiting value for computational stability of the model. Given the full model

equation set, this value is determined by a number of factors, including wind velocity,

internal gravity wave speed, external gravity wave speed (related in part to the height of

the model domain), vertical and horizontal grid spacing, and maximum terrain slope. It

is not easy to provide a comprehensive formula for estimating an optimal value for

DTLONG, and the user should generally try a few values when beginning a new

simulation to find a suitable value. However, some guidelines can be provided based

on experience. For a deep model domain, say 20 km or more, the model timestep can

usually be 5 or 6 seconds for a 1 km horizontal spacing, 30 seconds for a 10 km

spacing, 90 seconds for a 60 km spacing, and 180 seconds or more for spacings over

150 km. In a shallow domain 3 km deep, we have been able to set DTLONG to 6

seconds with a 125 meter horizontal spacing. When steep terrain is used (the relevant

measure of steepness appears to be the maximum change in terrain height between two

adjacent grid cells in vertical grid spacing units, with a value over about 5 being

considered steep), DTLONG is often required to be smaller. If IDELTAT is not

set to zero, the model will compute DTLONG itself based on grid spacing and other

factors, and the value specified in the namelist will be ignored.

NACOUST

Number of short or acoustic timesteps performed for each long timestep on a grid. If

Integer

IDELTAT is set to zero, the value specified for NACOUST in the namelist is used for all grids. If

IDELTAT is not equal to zero, the namelist value is ignored and the model will compute an

appropriate value which may differ between grids. The short timesteps are used for

evaluating the pressure gradient force and divergence equation terms and applying

them to the velocity and pressure fields, i.e. , the terms involving the propagation of

sound waves. The long timestep is used to evaluate most other terms, including

advection, diffusion, Coriolis force, and microphysical tendencies. This practice of time

splitting of the prognostic equations allows full explicit computation (on the short

timestep) of the terms governing the rapidly moving sound waves, while the terms

governing slower processes can be performed on the long timestep. NACOUST has

nothing to do with the relation between timesteps of one grid and another. On the

coarse grid, the long timestep is defined by DTLONG, defined above. A separate, grid-

dependent variable DTLONGN, which is not defined in the namelists but is internal to

the code, is the specific timestep length for each grid. It is equal to DTLONG (defined

above) on the coarse grid, and is determined for the finer grids from a combination of

DTLONG and NNDTRAT, defined below in this Section. The length of the short

(sound wave) timestep is twice the ratio DTLONGN/NACOUST. This short timestep

must be short enough (by using a sufficiently large value of NACOUST) that sound

cannot travel more than one half the horizontal grid spacing during the short timestep.

Sound normally travels more than 300 meters per second, but the model will artificially

slow it down if on any grid the short timestep is too large for the grid spacing. A

message is printed out stating how much the sound speed has been reduced, with a

warning if it is too slow. If this occurs, DTLONGN should be reduced, either by

reducing DTLONG, by increasing NNDTRAT, or both.

NSTRATX

Number of grid cells in the x-direction in a fine grid which span the x dimension of

integer array

a single grid cell of the coarser parent grid to that fine grid. In other words,

NSTRATX is the factor of increase in resolution in the x-direction between

consecutive nesting levels. For example, if the third value of NSTRATX is set to 4

and the third value of NXTNEST is set to 2, grid 2 will be the parent of grid 3, and

grid 3 will have 4 times the resolution or one fourth the grid cell size of grid 2 in the

x-direction. If in the same example, the second value of NSTRATX were also 4,

grid 3 would have 16 times the resolution of grid 1 in the x-direction. The example

shown in Figure 1 has NSTRATX set to 2 for grid 2. An important constraint

between the values of NSTRATX and NNXP must be observed for fine nested

grids. A fine grid must exactly cover an integer number of grid cells in its coarser

parent grid with its interior cells (defined in the entry for NNXP), and must have the

two additional boundary cells. Thus, NNXP for any nested grid must be some

integer number (of coarser grid cells covered - 2 in the example of Figure 1) times

NSTRATX for that nested grid (3 in the example of Figure 1) plus 2. For

NSTRATX and for other related nest configuration variables, if the required

combinations of these are not met, the model will stop and issue a message

suggesting an acceptable value. Values of 3, 4, and 5 have been most commonly

used for NSTRATX. A value of 2 is not usually considered a sufficiently large

increase in resolution to make nesting worthwhile, while values of 6 and larger are

more prone to cause reflections at the nesting boundaries due to the larger disparity

of resolvability between the two grids. (Also see NINEST.)

NSTRATY

Similar to NSTRATX, but applies to the grid resolution ratio in the y-direction. In

integer array

the example of Figure 1, NSTRATY is set to 2. If NNYP is set to 1, so that the

simulation is 2-D, NSTRATY must be set to 1 for all grids activated.

NNDTRAT

Number of timesteps which a fine grid is to be executed to advance it in time the

integer array

same amount as a single timestep of the coarser parent grid. Because the fine grid

has a smaller cell size, it must normally be run with a smaller time step for

numerical stability, and the time step length will automatically be made inversely

proportional to NNDTRAT. As an example, if the second value of NNDTRAT is

set to 4, and the timestep on grid 1 happens to be set to 20 seconds (see DTLONG ),

grid 2 will run on a 5-second timestep, four of which will be performed for each

timestep of grid 1. The longest timestep on which a grid can be run stably is not

directly proportional to the cell size, but tends to increase more slowly. Thus, a

finer grid nested within a coarse grid at say a 3:1 ratio can normally be run at longer

than the expected 1/3 of the coarse grid timestep; 1/2 of the coarse grid timestep

may be acceptable. If IDELTAT is set to zero, the values specified in the namelist

for NNDTRAT will be used. If IDELTAT is not zero, values specified in the

namelist for NNDTRAT will be ignored and the model will instead compute them

automatically.

NESTZ1

Parameter whose absolute value denotes the number of the nested grid, if any, that is

integer

to be nested with a higher vertical resolution than its parent (see NSTRATZ1).

Such vertical nesting may be done for only one of all model nested grids. Any

additional grids that are nested within this grid will use the same vertical grid

spacing. Because the vertical nesting ratio can be made variable with height

between this nested grid and its parent, the vertical grid spacing of the nested grid

may jump suddenly from one vertical level to the next. In order to reduce the

relative amount of jump (that is, the ratio of vertical grid spacing between

consecutive levels), the model can automatically compensate somewhat by making

adjustments to the vertical grid spacings in the parent and coarser grids. This option

is activated by giving NESTZ a negative value (of the grid to which it applies). If

NESTZ is set to 0, no vertical nesting will be done.

NSTRATZ1

Related to NSTRATX, but applies to the grid resolution ratio in the z-direction.

integer array

Unlike NSTRATX, however, NSTRATZ is not a grid-dependent parameter, but

refers to the vertical nest ratio between a particular nested grid, specified by the user

in the namelist variable NESTZ, and its parent. NSTRATZ is nevertheless a multi-

valued parameter, to allow the vertical nest ratio to be varied with height. Each

value specified signifies the number of fine grid levels contained in a single level of

the parent grid, beginning with the K = 1 level of the parent grid and continuing

upward (see Figure 2). Only those levels up to the last one having a vertical nest

ratio greater than 1 need be entered in the namelist, because all others are assigned a

value of 1 by default. Also, the first value specified in the namelist is not actually

used, because it is reassigned in the code. Nevertheless, some value must be entered

to serve as a placeholder in the namelist so that the subsequent values are in the

proper location. This feature has most often been used to enhance vertical

resolution close to the ground on a nested grid, in which case a decreasing sequence

such as NSTRATZ = 4, 4, 4, 4, 3, 3, 3, 2, 2, 2, may be used. In this example, the

lowest 3 levels of the parent grid will have 4 fine grid levels within each one, the

next 3 will have 3 fine grid levels within each one, and the next 3 will have 2 fine

grid levels within each one. The remaining levels will have a 1-to-1 vertical nesting

ratio. The feature may also be used to enhance vertical resolution in a selected

elevated region, such as a cloud layer. Values specified for NSTRATZ 1must not

differ by more than 1 between consecutive entries. Use of vertical nesting is not

necessarily the best means of increasing vertical resolution in all cases. The

alternative method of increasing vertical resolution over a limited vertical extent of

the model domain (but over the entire horizontal extent) has been to stretch the

vertical grid spacing (see DZRAT). For this choice, NSTRATZ could be set to 1,

although a combination of both methods of stretching is possible, if desired.

NESTZ2

Like NESTZ1 except that it is used only if RAMS is run on a global domain, and

integer

applies only to the set of nested grids within the second hemispheric coarse grid

(NESTZ1 will always apply to nested grids within the first (hemispheric) grid (grid

1).

NSTRATZ2

Like NSTRATZ1 except that it is used only if RAMS is run on a global domain,

integer array

and applies only to the set of nested grids within the second hemispheric coarse grid

(NSTRATZ1 will always apply to nested grids within the first (hemispheric) grid

(grid 1). NSTRATZ2 may be different from NSTRATZ1, allowing different

nesting design in each hemisphere.

POLELAT

Geographic latitude and longitude in degrees (ranging from -90 to 90 and -180 to

POLELON

180, respectively) of the pole point, or point of tangency between the model polar

stereographic grid and the earth. This location also serves as the origin (x = 0,y = 0)

real

on the polar stereographic grid. If RAMS is run on a global domain, the second

hemispheric grid and any nested grids within it use a polar stereographic projection

tangent to the earth at the point opposite POLELAT and POLELON.

CENTLAT

Grid-dependent parameters for the geographic latitude and longitude in degrees

CENTLON

(ranging from -90 to 90 and -180 to 180, respectively) of the center of each model

grid. They are used to define the position of the grids in earth coordinates for the

real array

purpose of determining the Coriolis force, the solar radiation, and the location of the

model domain relative to observed meteorological and land surface data. For the

coarsest model grid, CENTLAT and CENTLON are the only means of specifying

the center location. Nested grid locations may also be specified relative to their

parent grids from variables NINEST, NJNEST, NSTRATX, and NSTRATY.

Only if NINEST and NJNEST are given zero values will CENTLAT and

CENTLON be used to determine the nested grid location. In such cases, because of

the precise positioning of grid lattice points required between a nested grid and its

parent, CENTLAT and CENTLON will be only approximate, and the precise

location of the nested grid will be the closest allowable position to that which they

indicate.If RAMS is run on a global domain, values of CENTLAT and

CENTLON are ignored for the two coarse hemispheric grids. CENTLAT and

CENTLON for grid 1 are set equal to POLELAT and POLELON, and

CENTLAT and CENTLON for the other hemispheric coarse grid are set to the

location on earth opposite POLELAT and POLELON.

NINEST

Location within a coarser parent grid where the western edge of a nested grid is to

integer array

be located. To be specific, we refer to the example in Figure 1. Here, the western

edge of grid 2 (the western edge always being defined by the lattice line passing

through the u-velocity points having an index i = 1) is located along the coarse mesh

line passing through the U-velocity points having an index I = 3. This configuration

would be established by setting the second value (for grid 2) of NINEST to 3. Note

that the value of NINEST for a nested fine grid always refers to the I-index in the

coarser parent grid of a row of U-velocity points. An important constraint involving

NINEST, NNXP, and NSTRATX is that the edge of a fine nested grid cannot be

any closer than two cells of the coarser parent grid from the lateral parent grid

boundary. The example in Figure 1 is right at this limit on both the eastern and

western boundaries of the fine grid: NINEST is set to 3, which places the western

boundary of the fine grid just two coarse cells from the coarse-grid western

boundary, and the eastern boundary of the fine grid is along the I = 5 index row of

coarse grid U-velocity points, which is just 2 coarse cells away from the coarse-grid

eastern boundary at I = 7.

NJNEST

Similar to NINEST, but locates the southern boundary of a fine grid within the

integer array

coarser parent grid. Here, the J-index of the coarse-grid V-velocity points is what is

referred to by the value of NJNEST. In the example of Figure 1, the second value

of NJNEST (for grid 2) would be 3. The constraints described for NINEST

likewise apply to NJNEST for the y-direction.

NKNEST

Related to NINEST, but locates the bottom boundary of a fine grid within the

integer array coarser parent grid. Here, the K-index of the coarse-grid W-velocity points is what is

referred to by the value of NKNEST. Unlike the case for NINEST and

NJNEST, NKNEST can be set to 1, if desired. Doing so would cause the nested

grid to begin at the ground, like the coarser parent grid. If the fine nested grid is to

begin at some height above the ground, NKNEST can be set to a larger number.

NKNEST can never be set to 2, however; nor can the combination of NKNEST,

NSTRATZ, and NNZP be such that the top of a fine nested grid be located exactly

one cell of the coarser parent grid below the top of that parent grid. Another

constraint is that NKNEST may not be set to 1 for a nested grid if its direct parent

grid does not itself begin at the ground. The configuration where a fine nest does not

extend to both the ground and the model domain top has been relatively little used.

In some cases, vertical motion impinging on a top or bottom nesting boundary of

differential horizontal resolution causes strong numerical reflections. In addition,

two model algorithms that involve vertical transport, radiative transfer and

sedimentation of hydrometeors have not been programmed for transfer between

different nested grids. For this reason, a nested grid should begin at the ground and

extend to the model top except in a few specialized applications.

NNSTTOP

Grid-dependent flag to indicate whether each grid extends to the coarse grid top. It

integer array must be set to 1 to indicate that a grid does reach the domain top, and set to 0 to indicate

that the top boundary of a grid is below the model domain top. In view of

the recommendation given under the entry for NKNEST, NNSTTOP should

normally be set to 1. Of course, since grid 1 always extends to the model domain

top, the first value of NNSTTOP must always be set to 1. The specified values of

NNZP, NKNEST, and NSTRATZ will themselves determine where the top of a

fine nested grid is in relation to the model domain top. The user must insure that this

is in agreement with the setting of NNSTTOP. If not, the model will give a fatal

error message and stop.

NNSTBOT

Similar to NNSTTOP, but indicates whether a nested grid has its lower boundary at

integer array the lower model boundary (the ground) or above it. NNSTBOT must be set to 1 if the

fine nested grid begins at the ground, and 0 if it does not. Similar to the case for

NNSTTOP, the model will check for agreement between NNSTBOT and the values

of NKNEST, and will stop with a fatal error message if agreement is not met.

GRIDU

Currently not working in v5.x

Real array

GRIDV

Currently not working in v5.x

Real array

3. The $CCATT_INFO namelist consists of variables that control the activation of the

Coupled Chemistry-Aerosol and Tracer Transport (CCATT) chemistry model, and

specifies the variables needed.

CCATT

The main flag to activate the chemistry and aerosol models in BRAMS

Integer

0= OFF

Range: 0, 1

1= ON

CHEMISTRY

Defines the complexity level of chemistry/aerosol sub-‐models to be

integer:

executed.

Range:

-‐1: this option turn OFF the chemistry/aerosol models. Only the

-‐1 to 4

meteorological model wil be executed.

0: activates the tracer transport model where emissions, advection,

diffusion and dry and wet depositions are turned ON but not chemical

reactivity. Al processes are in-‐line and consistent with the meteorological

model.

1: the same as 0 but chemical reactivity is turned ON using the QSSA

solver. Important: this solver is obsolete and should not be used. Future

model versions wil remove this option.

2: the same as 0 but chemical reactivity is turned ON using the Rosenbrock

2nd order solver.

3: the same as 0 but chemical reactivity is turned ON using the Rosenbrock

2nd order solver together with a varying chemical time step to optimize

accuracy, stability and computational efficiency.

4: the same as 0 but chemical reactivity is turned ON using the Rosenbrock

3rd order (RODAS3) solver together a varying chemical time step to

optimize accuracy, stability and computational efficiency.

The option 4 is strongly recommended for simulations with chemistry,

mainly for long-‐term runs.

SPLIT_METHOD

Defines the kind of splitting operator to be applied to integrate the full

Character

mass continuity equation for each chemical tracer.

The values for this variable are:

• ‘PARALLEL’: parallel time splitting as originally developed by the

RAMS model. The same as applied for the scalars theta_il, tke, etc.

In this this case, the parameter CHEM_TIME_STEP (see below)

must be set equal do ‘DTLONG’.

• ‘SEQUENTIAL’: sequential (or serial) time splitting. In this method,

the tracer chemical mixing ratio is first integrated using the

transport, emission and removal processes. Then using the mixing

ratio just updated, the chemical solver is applied.

• ‘SYMMETRIC’: sequential, symmetric time splitting: dynamics

-‐>chemistry -‐> dynamics.

Important: SYMMETRIC splitting is recommended

CHEM_TIMESTEP This parameter provides de maximum time step to be applied by the

Real

chemical solver. It is be specified in seconds and must be a multiple of the

dynamics time step (the RAMSIN parameter named “dtlong”). In this way,

it must be defined as:

CHEM_TIMESTEP = N* DTLONG

Where :

N = 1, 2, 3 ,4, 6 for the parallel or sequential splitting methods.

N = 2, 4, 6 for the symmetric splitting method.

As an example, if the user chooses dtlong = 10, chem_timestep should be

set as 10, 20, 30, 40 or 60.

Important: it is strongly recommend do not use N greater than 6 for

keeping reasonable accuracy of the chemical solver. The recommended

optimal value (accuracy and efficiency) for the parameter N is 4.

However, it is always recommended to the users to make sensitive testing

of your case study using N from 1 to 6 to check the convergence of the

solution and if the error is acceptable.

CHEMISTRY_AQ

Parameter that activates (1) or deactivates (0) aqueous phase chemistry.

Integer

Only for RACM chemical mechanism.

Range: 0,1

CHEM_ASSIM

Activates the four-‐dimensional data assimilation (nudging) of chemical

Integer

species together with the meteorological fields.

Range: 0, 1

0 : turn OFF

1 : activates

RECYCLE_TRACER Activates the tracer initialization from a previous model run.

S

0 : turn OFF

Integer

1 : activates

Range: 0, 1

When activates, the model analysis used to initiate the tracer field must

be informed at RAMSIN parameter PASTFN do RAMSIN (section

$MODEL_FILE_INFO). As an example:

PASTFN = ‘RACM-‐A-‐2005-‐06-‐30-‐000000-‐head.txt',

SRCMAPFN

PREFIX nama of the emission files. As an example :

Character

SRCMAPFN = '/user1/model/SRC_RACM/experiment-‐saopaulo’,

In case of emission wil not be included in the model simulations, set

SRCMAPFN = 'NONE’

DEF_PROC_SRC

Tel s to the model what to do in case of an emission file does not exist or is

Character

not find in the directory during the run time:

‘STOP’ : model execution is aborted.

‘LAST_SOURCES’: model uses the previous day emission file (model wil

repeat the emission fields for the current day simulation).

DIUR_CYCLE

A value of 1 wil apply prescribed diurnal cycles of emissions. This is the

Sequence of 4

default setting. In this case, emission files wil be read each 24 hours.

integers with the A value 0 is reserved for future implementation of hourly interpolation.

range 0 or 1.

The order of these parameters are:

'antro ' ,'bburn', 'bioge ,'geoge’

NA_EXTRA2D

Number of extra arrays 2d (nx,ny) and 3d (nz,nx,ny) to be allocated for the

NA_EXTRA3D

user customized fields.

Both integers

Range >= 0

PLUMERISE

Controls the activation of the plume rise transport of emissions associated

Integer

with biomass burning.

Range : 0 or 1

0 : turn off (all emissions are released in the first model layer)

1 : activates the plume rise mechanism for the flaming phase emissions.

An injection layer is prognostic in-‐line with the model evolution for the

fraction of the emissions produced during the flaming phase.

PRFRQ

Set the frequency (in seconds) that the plume rise model is called to

Real

update the injection height of biomass burning emissions. Must be a

multiple of DTLONG parameter. Typical tested values are 1800, 3600 and

7200 seconds.

VOLCANOES

Controls the activation of volcanic emissions (currently SO2 and ash).

Integer

0 : turn OFF

Range: 0 or 1

1 : activates

AEROSOL

Parameter that activates or not the aerosol models

Integer

0 : turn OFF

Range: 0, 1, 2

1 : activates the simplified aerosol model.

2: activates MATRIX aerosol model (currently, not ful y tested yet)

Important: The direct effect of aerosols is implemented in CARMA

radiation scheme only (ISWRTYP = 4 and ILWRTYP = 4)

AER_TIMESTEP

Aerosol model time step integration (sec). Must be an multiple of dtlong

REAL

(max 4) only for the matrix aerosol model (AEROSOL=2)

Range: 1 to 4 times

dtlong

$TEB_SPM_INFO namelist

The $TEB_SPM_INFO namelist consists of variables that control the

activation of the Town Energy Budget (TEB) and the Simple Photochemical

Module (SPM) emission model, and specifies the variables needed in this

special case of simulation.

Variable name

Description

Flag that allows active (1) the TEB_SPM section, including

TEB_SPM

options to run

the Town Energy Budget (TEB) and the Simple Photochemical

Module

(SPM) emission model, or deactive (0).

File path and prefix for local time files. If the file does not exist

FUSFILES

the model

will generate from a global time files (defined in IFUSFN).

Character array

Array of integer where the user can set values for each grid

IFUSFLG

used. The

value 1 set the model to read from standard Lat/Lon local time

data file, 0

Integer array

define that the model will calculate the values of local time.

IFUSFN

File path and prefix for global time files.

Character array

Photochemical module activation –(1=on, 0=off). Activation

ICHEMI

requires

ISOURCE to be equal to 1

Integer

Use initial values from previous run (1=yes,0=no) for

ICHEMI_IN

Photochemical data.

Integer

File with Photochemical data from a previous run to be used as

CHEMDATA_IN

initial

value (if ICHEMI_IN=1).

Character

Urban vehicular and industrial emission activation –(1=on,

ISOURCE

0=off).

Integer

Initial weekday of the simulation. This will be also used by

WEEKDAYIN

TEB.

Character

RUSHH1

Morning Rush Hour (Local Time in Hours).

Real

RUSHH2

Afternoon/Evening Rush Hour (Local Time).

Real

DAYLIGHT

Daylight saving time.

Real

Emission factor (fraction of weekdays) for Saturdays. It is used

EFSAT

in the

emission module and TEB.

Real

Emission factor (fraction of weekdays) for Sundays. It is used

EFSUN

in the

emission module and TEB.

Real

EINDNO

Industrial emissions for NO in kg/s/m2.

Real

EINDNO2

Industrial emissions for NO2 in kg/s/m2.

Real

EINDPM

Industrial emissions for Particulate Material in kg/s/m2.

Real

EINDCO

Industrial emissions for CO in kg/s/m2.

Real

EINDSO2

Industrial emissions for SO2 in kg/s/m2.

Real

EINDVOC

Industrial emissions for VOC in kg/s/m2.

Real

EVEINO

Vehicular emissions for NO in kg/day/m2.

Real

EVEINO2

Vehicular emissions for NO2 in kg/day/m2.

Real

EVEIPM

Vehicular emissions for Particulate Material in kg/day/m2.

Real

EVEICO

Vehicular emissions for CO in kg/day/m2.

Real

EVEISO2

Vehicular emissions for SO2 in kg/day/m2.

Real

EVEIVOC

Vehicular emissions for VOC in kg/day/m2.

Real

TMINBLD

Minimum internal building temperature (degrees Celsius)

Real

Number of roof, road and wall layers used in TEB (Maximum of

NTEB

3)

Integer

HC_ROOF

Heat capacity for ROOF layers.

Real

TC_ROOF

Thermal conductivity for ROOF layers.

Real

D_ROOF

Depth for ROOF layers.

Real

HC_ROAD

Heat capacity for ROAD layers.

Real

TC_ROAD

Thermal conductivity for ROAD layers.

Real

D_ROAD

Depth for ROAD layers.

Real

HC_WALL

Heat capacity (J/m3/K 10e6) for WALL layers.

Real

TC_WALL

Thermal conductivity (0.81 W/m/K) for WALL layers.

Real

D_WALL

Depth for WALL layers.

Real

NURBTYPE

Number of urban types (maximum of 3).

Integer

Leaf class code to identify each urban type. The number of

ILEAFCOD

elements for

this array is determined by the values in NURBTYPE.

Integer array

Urban type roughness length (between 5 and 1). The number

Z0_TOWN

of elements

for this array is determined by the values in NURBTYPE.

Real array

Fraction occupied by buildings in the grid cell for each urban

BLD

type.

Real array

BLD_HEIGHT

Building Height for each urban type.

Real array

Vertical/Horizontal rate (between 3 and 0.5) for each urban

BLD_HL_RATIO type.

Real array

AROOF

Roof albedo for each urban type.

Real array

EROOF

Roof emissivity for each urban type.

Real array

AROAD

Road albedo for each urban type.

Real array

EROAD

Road emissivity for each urban type.

Real array

AWALL

Wall albedo for each urban type.

Real array

EWALL

Wall emissivity for each urban type.

Real array

Maximum value of sensible heat released by Traffic (W/m2) for

HTRAF

each

urban type.

Real array

Maximum value of sensible heat released by Industry (W/m2)

HINDU

for each

urban type.

Real array

Maximum value of latent heat released by Traffic (W/m2) for

PLETRAF

each urban

type.

Real array

Maximum value of latent heat released by Industry (W/m2) for

PLEINDU

each urban

type.

Real array

$MODEL_FILE_INFO Namelist

The $MODEL_FILE_INFO namelist consists primarily of variables that control

data input to and data output from the model. The names of files containing these

data are specified here, as well as the times during a model simulation when the

data are read or written. The information in this namelist also controls some

aspects of how input data is to be used.

INITIAL

Specifies how atmospheric fields in the model are to be initialized.

integer

INITIAL = 1: the atmospheric variables are initialized horizontally

homogeneously from a single sounding, which the user supplies in

namelist $MODEL_SOUND. This option is typically used when the

model domain is of relatively limited size (a few hundred kilometers

across or less), and is required if the model is run in 2-‐D. Lateral

boundaries in this case are open, and are updated based on interior

values or are held constant in time.

INITIAL = 2: the sounding in namelist $MODEL_SOUND is not used,

and instead, the model inputs complete 3-‐D fields of atmospheric data

from varfiles, which have been earlier generated by the model from

isentropic output from ISAN (see RUNTYPE). These fields are used

both as initial fields in the model and as time-‐dependent fields to

which the lateral boundary region of the model is nudged during

integration.

INITIAL = 3: the initial fields will be defined by interpolation from a

previous RAMS’ history file, as specified in HFILIN. The new run will

start at model time 0. The grids in the current run do not have to have

the same structure as the grids on the history file, except that the new

grid 1 must fit within the history file grid 1. All other nested grids in

the current run are interpolated from the current coarse grid by

standard nesting procedures. This capability is mainly intended for

situations where the new coarse grid is very different than the old

grid structure. This should not be used if a nested grid is added or

subtracted; use the standard RUNTYPE=’HISTORY’ instead.

INITIAL = 4: initial fields are defined by a using prior model’s analysis

output (in vfm format), like a downscaling. The prefix name and

directory address of these files are set using the VARFPFX variable.

Further details regarding the use of the initialization options are given

in descriptions of several variables in this Section.

NUD_TYPE

Specifies what type of analysis nudging scheme to use in the 4-

dimensional data assimilation (4DDA). The term analysis nudging

integer

refers to a scheme where all or a portion of the domain is nudged

toward a gridded data analysis. This can also be applied to nudging

toward a previous simulation of RAMS or other model output.

NUD_TYPE = 0: no analysis nudging is performed. This would

generally be the setting if INITIAL=1.

NUD_TYPE = 1: analysis nudging is performed using data from

RAMS history files, with the nudging strengths and settings

controlled by the analysis nudging parameters below. All grids are

interpolated or defined from the highest resolution information

available on the history file. This is a way to activate a one-way

nesting scheme, although we only recommend using a one-way

nest only in special circumstances.

NUD_TYPE = 2: analysis nudging is performed using data from the

varfiles, with the nudging strengths and settings controlled by the

analysis nudging parameters below.

NUD_TYPE = 3 is not in use.

NUD_TYPE = 4: analysis nudging is performed using output

analysis data from a prior run (see description about the ÏNITIAL”

parameter), with the nudging strengths and settings controlled by

the analysis nudging parameters below.

VARFPFX

Prefix that begins the names of the initialization files called varfiles,

(including path names if applicable) to be read into the model, for

character

cases when the INITIAL=2 (and/or NUD_TYPE=2). These files are

output from a previous model run with RUNTYPE set to

'MAKEVFILE' (see VARPFX). If INITIAL is set to 1 or 3, this

parameter is ignored.

For cases when the INITIAL=4 (and/or NUD_TYPE=4) the files

come from a previous model run.

VWAIT1

Used only for automated operational model runs in which an

attempt is made to acquire the varfiles data for input to RAMS. If

real

this attempt is unsuccessful and a varfile is not available, the model

is instructed to wait a time interval given by VWAIT1 (seconds),

before attempting again.

VWAITTOT

Similar to VWAIT1 and likewise used only for automation of

operational runs. Specifies the total amount of time to continue

real

waiting for a completed varfile before giving up altogether.

NUD_HFILE

Analysis state files to be read for use in the history file nudging

scheme (NUD_TYPE=1). The character string placed in this

character

variable must be the full name of the state header file, including the

appropriate path if applicable. However, only the prefix information

is used to determine the set of state files to be used. Further details

on the standard syntax of the analysis file names are given in the

description of AFILOUT.

NUDLAT

Parameters that control the option of four-dimensional data assimilation

integer

(4DDA) by Newtonian relaxation (nudging). This is also termed analysis

nudging, since we will be nudging toward a gridded data analysis. This

TNUDLAT

4DDA option requires that the INITIAL variable is set to 2 or 3, so that the

TNUDCENT

model is initialized from varfiles or a previous RAMS run. The varfiles or

history files contain time series of gridded horizontal wind, potential

TNUDTOP

temperature, and total water mixing ratio values, usually analyzed from

ZNUDTOP

observations or sometimes large-scale model forecasts. The atmospheric

real

model solution is relaxed toward the analyzed data during time integration.

The strength of the nudging is given by (I-M)/T, where I is a varfile data

value at a particular location, M is the corresponding model value, and T is a

user-specified relaxation (e-folding) time scale. RAMS contains a 3-D array

of T values for each grid so that the nudging strength can be specified in a

customized way by modifying code. However standard distributions of T

may be easily defined through the namelist variables TNUDLAT,

TNUDTOP, and TNUDCENT, which define relaxation time scales at the

lateral boundary, top boundary, and center regions, respectively, of the

model domain. The influence of TNUDLAT extends inward from the

lateral boundary of the model domain (coarse grid) by a number of grid cells

specified by the user in namelist parameter NUDLAT. The influence

function (inverse time scale) increases outward parabolically beginning

from the parabola vertex located NUDLAT points in from the boundary.

The nudging time scale at that vertex and deeper in the interior of the grid is

defined by TNUDCENT. Thus, TNUDCENT can be used to specify a

lower bound on nudging strength throughout the domain. The influence of

TNUDTOP extends downward from the model domain top to a height

specified in namelist variable ZNUDTOP. The influence function increases

linearly between these two heights, reaching the minimum value defined by

TNUDCENT at and below ZNUDTOP. Note that as time scales are

inversely proportional to nudging strength, TNUDCENT should have a

larger value than TNUDLAT and TNUDTOP for nudging to strengthen

toward the lateral and top boundaries. Use of TNUDLAT and NUDLAT is

a replacement for the specification of the Davies lateral boundary nudging

in 2c and earlier versions of RAMS. Use of TNUDTOP and ZNUDTOP

functions analogously to the Rayleigh friction top boundary condition (see

descriptions for DISTIM and NUPTS), but can be used for observational

data fields which are not horizontally homogeneous. This provides a means

for damping upward-propagating gravity waves which could otherwise

reflect off the top model boundary. TNUDCENT is a part of the data

assimilation capability in RAMS, and is definable in the namelist in order to

conveniently activate domain-wide nudging. Users of the nudging option

should experiment with all three nudging time scales to determine the values

which work best for a particular application. The only constraint for

numerical stability is that none of the time scales can be less than the model

timestep, except that setting TNUDLAT, TNUDTOP, and TNUDCENT to zero turns off the nudging option. Experience has shown that values of

TNUDLAT should typically be in the range of 900-1800 seconds,

TNUDCENT = 3600 corresponds to very strong nudging and usually is

better in the 7200-14400 second range. TNUDTOP frequently does not

need to be used and should only be activated at levels well into the

stratosphere. Furthermore, if TNUDTOP is used, special care should be

taken to examine its impact on the model solution, because the impact can

be quite strong.

WT_NUDGE_GRID

relative weights applied to the nudging weights for each grid. The main

real array

intent is to have user control over the 4DDA analysis nudging weights on

individual grids. The base weights are determined from the timescale

TNUDCENT, then multiplied by WT_NUDGE_GRID. A value of 2., for

example, will double the nudging strength on that grid. Care must be taken

that all adjustments of nudging strength fall with the numerical stability

limits

WT_NUDGE_UV

relative weights applied to the nudging weights for specific variables. The

WT_NUDGE_TH

main intent is to have user control over the 4DDA analysis nudging weights.

WT_NUDGE_PI

The base weights are determined from the timescale TNUDCENT, then

WT_NUDGE_RT

multiplied by WT_NUDGE_UV, etc. WT_NUDGE_UV is applied to the u and v

real

components, WT_NUDGE_TH is applied to potential temperature,

WT_NUDGE_PI is applied to the Exner function, and WT_NUDGE_RT is

applied to total water mixing ratio.

The complete computation of the nudging weight for the analysis nudging

4DDA (in the “center” of the domain) is then computed by:

(WT_NUDGE_GRID(ngrid) * WT_NUDGE_UV) / TNUDCENT

flag to activate a condensate nudging 4DDA scheme. This scheme follows

the same types of procedures as the history nudging scheme

NUD_COND

(NUD_TYPE=1), but only nudges total water mixing ratio at grid points

integer

where condensate exists. This is intended primarily for assimilation

purposes in operational forecast cycles.

COND_HFILE

History files to be read for use in the condensate nudging scheme

character

(NUD_COND=1). The character string placed in this variable must be the

full name of the history header file, including the appropriate path if

applicable. However, only the prefix information is used to determine

the set of history files to be used. Further details on the standard syntax

of the history file name are given in the description of HFILOUT.

TCOND_BEG

beginning and ending model time (seconds) to start and stop the

TCOND_END

condensate

real

nudging scheme.

WT_NUDGEC_GRID

relative weight of the condensate nudging scheme for each grid

real array

T_NUDGE_RC

timescale for the condensate nudging scheme. The complete computation

real

of the condensate nudging weight is then computed

by:

(WT_NUDGEC_GRID(ngrid) * WT_NUDGE_RC) / T_NUDGE_RC

Flag to active the ODA (observational data assimilation) feature, a

IF_ODA

generalized observational nudging scheme. The ODA scheme will

examine each station, interpolate in time to each timestep (if the

observations are close enough), then perform a “kriging” interpolation to

integer

produce three-‐ dimensional value and covariance fields. The combination

of the value and covariance fields will only nudge the model fields in

locations where the observations are “close enough”. The parameters

below will control the behavior of the ODA scheme.

ODA_UPA_PREFIX

File name prefixes (including path information) for the input surface (SFC)

ODA_SFC_PREFIX

and upper air (UPA) data for the ODA scheme. The file must be standard

RALPH II format and currently must contain one data time per file.

character

FRQODA

Frequency (seconds) at which to update the interpolated observational value

real

and covariance fields with the kriging scheme. This could be done every

timestep, but probably less often for efficiency. 10-20 minutes should be an

adequate compromise with standard synoptic observations, but it is

dependent on the specifics of the simulation and the available observations.

TODABEG

Beginning and ending model times (seconds) to start and stop the ODA

TODAEND

scheme.

real

TNUDODA

Main nudging ODA timescale (seconds). This determines, along with

WT_ODA_GRID and WT_ODA_UV, etc., the strength of the nudging.

For

example, the complete computation of the weight for the ODA nudging

real

for the

u and v components is computed by:

(WT_ODA_GRID(ngrid) * WT_ODA_UV) / TNUDODA

WT_ODA_GRID

Relative weights applied to the ODA nudging weights for each grid. See

real array

TNUDODA.

WT_ODA_UV

Relative weights applied to the ODA nudging weights for specific variables.

WT_ODA_TH

WT_ODA_UV is applied to the u and v components, WT_ODA_TH is

applied to potential temperature, WT_ODA_PI is applied to the Exner

WT_ODA_PI

function, and WT_ODA_RT is applied to total water mixing ratio. See

WT_ODA_RT

TNUDODA.

real

RODA_SFCE

Radii (meters) for the kriging scheme to control the smoothness of the

RODA_SFC0

analysis at the surface. SFC0 is the distance from an observation where the

influence becomes zero, while SFCE is the distance where the influence

real array

drops by a factor of e-2. These values are grid-dependent.

RODA_UPAE

Radii (meters) for the kriging scheme for the upper air observations to

RODA_UPA0

control the smoothness of the analysis in the upper air. UPA0 is the distance

from an observation where the influence becomes zero, while UPAE is the

real array

distance where the influence drops by a factor of e-2. These values are grid-

dependent.

RODA_HGT

The height (meters) above the ground used to determine the vertical structure

real array

of the kriging radii. RODA_SFC0 will apply at the ground, while

RODA_UPA0 will begin at a height of RODA_HGT. The radius will be held

constant at a value of RODA_UPA0 from RODA_HGT to the model top,

while a linear interpolation from the ground to RODA_HGT will be

performed. Typically, some height above the expected boundary layer depth

would be chosen. This value is grid-dependent.

RODA_ZFACT

Vertical exaggeration factor to control smoothness in the kriging scheme.

real

This is somewhat related to the ratio of horizontal grid spacing and vertical

grid spacing. A value of the order 100 is reasonable.

ODA_SFC_TIL

Time interpolation limit (TIL) and time extrapolation limit (TEL)

ODA_SFC_TEL

(both seconds) for the surface data in the ODA scheme. These are

real

used to determine the use of the observations at the time of the

kriging scheme updates. At an update time, each station will be

examined. A past and future observation time (with non-missing data)

relative to the update time will be found. If the future minus the past time

is less than the TIL, then the data values will be interpolated to the

update time for use in the data analysis. If this condition is not true, then

the past and future times will be checked tosee if it is less than the TEL.

If, for example, the past time is less than the TEL, then that data value

will be used in the analysis. For hourly surface observations, reasonable

settings might be ODA_SFC_TIL=7200., and ODA_SFC_TEL=900.

ODA_UPA_TIL

Time interpolation limit (TIL) and time extrapolation limit (TEL)

ODA_UPA_TEL

(both seconds) for the upper air data in the ODA scheme. See

real

ODA_SFC_TIL. For standard 12 hourly surface observations, reasonable

settings might be ODA_UPA_TIL=43200. and ODA_UPA_TEL=3600.

IF_CUINV

Flag to activate the reading and nudging toward heating and

moistening rates produced by the cumulus inversion scheme. This is a

integer

new experimental feature where the convective rates are produced

before the actual run by a separate process that reads observed

precipitation rates (from observations, satellite, or radar) and produces

the convective tendencies. Files for each time corresponding to the

availability of the precipitation rate data are produced. The rates are

further weighted with a typical nudging manner to allow for control over

the strength.

CU_PREFIX

File name prefix (including path information) of the files produced from

character

the cumulus inversion program.

TNUDCU

Main nudging CU timescale (seconds). This determines, along with

real

WT_CU_GRID, the strength of the nudging. The complete computation

of the weight for the CU nudging is computed by:

WT_CU_GRID(ngrid) / TNUDCU

WT_CU_GRID

Relative weights applied to the CU nudging weights for each grid.

real

See TNUDCU.

TCU_BEG

Beginning and ending model times (seconds) to start and stop the

TCU_END

CU nudging scheme.

real

CU_TEL

Time interpolation limit (TIL) and time extrapolation limit (TEL) (both

CU_TIL

seconds) for the CU scheme. See ODA_SFC_TIL. Reasonable settings will

be dependent on the time resolution of the original precipitation rate data.

real

TIMSTR

Time in seconds, minutes, hours, or days (see TIMEUNIT) already

real

accumulated in a simulation when a history restart of the model is to

commence. It must be equal to the cumulative simulation time at which the

history file to be used to initialize the current run was written. The time

interval obtained by subtracting TIMSTR from TIMMAX is the actual

simulation time that will elapse during the current run. TIMSTR is relevant

only if RUNTYPE is set to 'HISTORY'. If instead a history restart is not

being done, TIMSTR is ignored, and the model time counter is initialized at

time 0.

HFILIN

History file to be read for initializing the current run (INITIAL=’HISTORY’,).

The character string placed in this variable must be the full name of the history

character

header file, including the appropriate path if applicable.

Further details on the standard syntax of the history file name are given in the

description of HFILOUT.

IPASTIN

Flag to activate a “recycle” feature, where certain fields from a previous

analysis file may be read upon initialization of the current run. Currently,

only the LEAF variables are included in this process. All soil and vegetation

variables are read and any default initialization values are replaced. The grid

structure of the previous run must exactly match the grid structure of the

current run.

PASTFN

Analysis header file name, if IPASTIN=1, from which to read the recycle

fields. For flexibility, the file time does not necessarily have to match the

initialization time of the current run.

IOUTPUT

Flag controlling whether the model will output any history and analysis

integer

files. If set to 0, neither type of file will be generated. Setting IOUTPUT

to 1 causes the model to generate both types of output files, with both the

history and analysis files written in ASCII. Setting IOUTPUT to 2 causes

the model to generate both types of output files, with the history file written

in binary and the analysis file in ASCII. The purpose of a history file is

solely to store prognostic model variables and some additional information

generated in a model run so that a subsequent model run can be initialized

from the file to continue a simulation. The purpose of an analysis file is to

store model output to be used in producing graphic visualization of the

model output. In order for the generation of visual products to be performed

on a machine other than the one used for executing the model (this is useful,

for example, when the model is run on a supercomputer and the graphical

output is produced on a workstation), the analysis file currently is written in

a packed ASCII format for easy transfer between machines. Full precision

of the model variables is not required in generating visualization products,

so only 2 or 3 bytes of information are written to the analysis file for each

model word in order to minimize file storage space. Each of these 8-bit

bytes contains 6 bits of actual information from the model variables, a ratio

achieved by translation of model numerical values into a set of 64 different

ASCII characters.

If set to 5 will generate a special variable-resized output in order to be used

within INITIAL=4 feature. This output contains only U, V, PI, THETA and

RH variables by default, but if chemistry is active, it will add all concentrations

species of a given chemical mechanism to create a complete initial/boundary

condition file. FRQANL controls the writing frequency for those files.

IPOS

Flag to provides GrADS output during the model time run. See “POST”

Integer

namelist for details.

Range : 0,1,2

0-no files, 2-gra IP

ds O

filSe s, 1-hdf5(not available yet)

HFILOUT

Prefix for the history files output from the model. Only a single character

character

value is assigned to HFILOUT even if more than one history file is to be

written in the current run. HFILOUT is used as a prefix to the one or more

file names, making up the first part of each name, including directory path

information. The model itself appends the last part of each history file

name, according to the time during the simulation when the file is written

and the grid number. That is, a separate history file is written for each grid

number, as well as for each history write time. In addition, a single history

header file is written at each history write time. As the model appends both

the time and the grid number onto the history file prefix (given by

HFILOUT), each file name written during a simulation has a distinct name,

but all still share the common prefix. It is useful to include the letter 'h' in

the character string specified for this variable to help identify the output file

as a history file. HFILOUT is only relevant if IOUTPUT is set to 1,

indicating that history files are to be created.

AFILOUT

Similar to HFILOUT, but applying to the analysis files, rather than the

character

history files, to be output from a model run. It is useful to include the letter

'a' in the character string specified for this variable to help identify the

output file as an analysis file.

ICLOBBER

A flag indicating what the model should do if history and/or analysis files

integer

already exist from a prior run, and the model is about to write new files of

the same name in the same directory. If ICLOBBER is set to 0, the model

will stop and not overwrite the older files. If ICLOBBER is set to 1, the

model will continue and will write new files, overwriting the old ones.

IHISTDEL

A flag indicating what the model should do with history files from the

integer

current model simulation or run that were written at previous times, once the

latest history file has been successfully written. If IHISTDEL is set to 0,

the previous history files are retained. If IHISTDEL is set to 1, the

previous history files are deleted and only the latest one is retained. This

latter option saves disk space while keeping the latest history file to restart

from in case the model stops for some reason.

FRQHIS

Time interval in seconds at which successive history files are to be output

real

from the model. The model variable TIME begins at zero at the start of a

new simulation (and at the value of TIMSTR for a history file start) and

counts up to the value of TIMMAX for each run. (see RUNTYPE,

TIMSTR, and TIMMAX). When TIME reaches a multiple of FRQHIS, a

model history file is written. In addition, a history file is written out when a

model run terminates, even if TIMMAX is not set to an exact integer

multiple of FRQHIS. A history file is also written out when a model run

begins, even if the TIME variable is not then a multiple of FRQHIS. In this

latter case, if the model run is a history start, the initial history file will be

written at the same time as the history file that is read to initialize the run.

Because this could lead to a file name conflict (the files corresponding to the

same simulation time), the upper-case letter 'R' is appended to the initial

output history file following the HFUNITS suffix to denote a 'Restart'.

FRQANL

Similar to FRQHIS, but specifies the time interval between successive

real

writes of analysis files, rather than history files, from the model.

Analysis

files (and history files) may only be output at the end of a coarse grid

timestep (whose length is specified by DTLONG, but see IDELTAT also).

Thus, unless FRQANL is an exact multiple of DTLONG, the actual time

interval between analysis file write times will be irregular. Thus, the user

should usually make sure that FRQANL is an exact multiple of DTLONG.

If IDELTAT is not zero, in which case the model will choose the timestep,

and model will take the value of FRQANL into account to make sure that

analysis files are written at regular intervals. There now exist 4 different

types of standard analysis files that RAMS can output: (1) the conventional

analysis file whose frequency is controlled by FRQANL, (2) a ‘lite’

analysis file which is intended for a smaller set of output data so that it can

be written more frequently, (3) a ‘mean’ analysis file that contains time-

averaged fields, and (4) a ‘both’ analysis file that combines lite and time-

averaged properties. FRQLITE, FRQMEAN, and FRQBOTH control the

output frequencies of these latter 3 files.

FRQLITE

Similar to FRQHIS and FRQANL, but specifies the time interval between

real

successive writes of ‘lite’ analysis files. The lite files are intended for

writing variables at much more frequent intervals than analysis files, for use

in post-processing applications such as graphical display, but with much less

information. For example, a user may need surface variables to be output

frequently, but not three-dimensional upper air fields. Only the required

fields would be specified for output in the lite files. Alternatively, subsets

of fields, rather than the entire fields, may be output through use of namelist

variables XLITE, YLITE, and ZLITE (see below), although this option is

not yet available in RAMS version 5.0.

XLITE

Specifies beginning and end of range of i-index values of a subset of any

character

output field to be written to ‘lite’ analysis

files. See FRQLITE above.

Special syntax of the form ‘/0:0/’ is used where the two integer values,

when positive, indicate the actual starting and ending i-index values of the

range of values to be output, and when negative, specify the number of grid

points in from the left and right grid boundaries of the range limits. This

option is not yet implemented in RAMS so only the entire field may be

written to lite files.

YLITE

Similar to XLITE but specifies the range of j-index values in the y-

character

coordinate direction (usually approximately north-south).

Not

yet

implemented so only the entire field may be written to lite files.

ZLITE

Similar to XLITE but specifies the range of k-index values in the vertical

character

coordinate direction.

Not yet implemented so only the entire field may be

written to lite files.

NLITE_VARS

Number of variables to write to the “lite” analysis file. The actual variable

integer

names are specified in the variable LITE_VARS.

LITE_VARS

Variable names of the fields that will be written to the “lite” analysis files.

char array

The variable names correspond to the RAMS’ internal character ID strings,

which now can be found in the modules/mem_*.f90 files. For example, the

u-component is “UP”, potential temperature is “THETA”, etc. Any variable

that is in memory may be included, but care must be taken in parallel runs to

ensure that the field has been passed back to the master process.

AVGTIM

Averaging time period for special time-averaged arrays that may be output

real

to analysis file. Positive values for AVGTIM cause the file write time to be

centered in time within this averaging period, while negative values cause

the file write time to occur at the end of the averaging period.

FRQMEAN

Similar to FRQANAL, but applies to the output frequency of ‘mean’

real

analysis files, which are one of the 4 standard types of analysis files that

RAMS can write (see FRQANL).

FRQBOTH

Similar to FRQANAL, but applies to the output frequency of ‘both’

real

analysis files, which are one of the 4 standard types of analysis files that

RAMS can write (see FRQANL).

KWRITE

Flag specifying whether to write horizontal and vertical turbulent mixing

integer

coefficients for scalars to analysis files (0 = no, 1 = yes). If they are to be

written, two additional arrays are allocated, the mixing coefficients are

copied to these arrays when they are computed in the model, and the values

are saved in these arrays for when the analysis files are written. The mixing

coefficient values are sometimes needed for plotting, and they are needed

for the HYPACT model, which runs from RAMS output.

FRQPRT

Time interval in seconds at which various field values are to be output from

real

the model to the standard output file generated by a model run. The actual

fields or portions thereof to be output are specified via several variables in

the $MODEL_PRINT namelist. The relation between FRQPRT and the

model simulation time is the same as for FRQHIS.

INITFLD

Flag specifying whether the field values indicated in the $MODEL_PRINT

integer

namelist for output to the standard output file are to be output at the initial

time of the model run. A value of 0 will cause the values to not be output at

the initial time, while a value of 1 will cause them to be output at the initial

time.

SFCFILES

Filename prefix (including path information) for the surface files used in a

character

model simulation. These files contain topography, soil textural class,

vegetation type, and subgrid distribution of soil textural class, vegetation

type, and water surface areas defined on each model grid.

Surface files are always used in a model run. They are commonly made in a

separate model run that does not proceed with prognosing atmospheric

fields by setting RUNTYPE to ‘MAKELAND’ or ‘MAKESFC’. However,

if RUNTYPE is instead set to ‘MAKEVFILE’ or ‘INITIAL’, and if surface

files do not exist or are found to be inconsistent with model grid size,

location, etc., new ones will be generated. If they already exist from a prior

run, surface data is read from them. A separate surface file is generated for

each grid, and the grid number is appended to each filename in the format of

SFCFILES.g01, SFCFILES.g02, etc.

SSTFPFX

Filename prefix (including path information) for SST files used in a model

character

simulation. These files contain sea surface temperature data defined on

each model grid, and usually for multiple times. This data type is available

on standard RAMS data files defined globally on a latitude-longitude grid

with climatological values for each month of the year. Data in surface files

may be interpolated from these standard files, from other data sources, or

may be defined by other means. These choices are controlled by ISSTFLG.

SST files are always used in a model run. They are commonly made in a

separate model run that does not proceed with prognosing atmospheric

fields by setting RUNTYPE to ‘MAKESST’ or ‘MAKESFC’. If

RUNTYPE is instead set to ‘MAKEVFILE’ or ‘INITIAL’, and if SST files

do not exist or are found to be inconsistent with model grid size, location,

etc., new ones will be generated. If they already exist from a prior run,

surface data is read from them. A separate SST file is generated for each

grid and for each time available in the files from which the data are

interpolated.

ITOPTFLG

Grid-dependent flag specifying how terrain height data is to be obtained or

integer

computed for each model grid. If ITOPTFLG is set to 0 (allowed for a

array

nested grid only), topography for that grid will be interpolated from its

parent grid. This will result in relatively smooth topography on the nested

grid, but is required if the nested grid is required to move in time (see

GRIDU and GRIDV). If ITOPTFLG is set to 1, topography will be

interpolated to the grid from a standard RAMS topography dataset, currently

available at 30 arc-second intervals of latitude and longitude for all land

areas of the globe. A prefix for all filenames in this dataset is specified in

ITOPTFN. This is by far the most common way to initialize topography in

RAMS unless the experiment requires idealized or flat topography. If

ITOPTFLG is set to 2 for a grid, the model will call subroutine TOPTINIT

in the model file rsurf.f90 to assign the terrain height, which by default sets

it to zero. To override any of these choices, subroutine TOPTINIT_USER in

the file rsurf.f90, which is always called but contains only commented out

executable lines in its standard form, may be modified. The ruser.f90 file is

specifically intended for user modification when such a need arises.

Subroutine TOPTINIT_USER is normally constructed with an IF block

checking for the grid number (NGRID). The terrain height values must be

assigned for the appropriate grid number. It must be pointed out that if

nested grids are used, it is required that the terrain heights be compatible

between different grids. The compatibility requirement is two-sided: Fine

grid values corresponding to a single coarse grid cell must locally average to

the coarse grid terrain height value in that cell, and the fine grid values near

the lateral boundary of the fine grid must be those which would result from

a bi-quadratic interpolation from coarse grid values, according to the

standard nesting procedure. The model is designed to make the terrain

heights compatible automatically, and will alter the values assigned to a grid

in subroutine TOPTINIT or TOPTINIT_USER if they are not already

compatible between grids. A special word of caution is in order here. If a

fine grid that is to contain fine resolution terrain height data is to be

spawned on a history start at a time after the initialization time of a

simulation, the terrain height data on the coarser grids must already have

been compatible with it in the preceding portion of the simulation. This may

be done either by simply initializing the topography of the spawned grid

from its parent, or by generating surface files for all grids, including the one

to be spawned, before the simulation started. The latter choice provides for

the better-resolved topography on the spawned grid, but will also result in

very fine (at the 2-delta-x scale) features on its parent grid. This may cause

some model noise problems during that earlier part of the simulation on the

portion of the coarser grids where the fine grid will be later inserted, but this

is normally at acceptable levels (see TOPTWVL).

ISSTFLG

Grid-dependent flag specifying how the sea surface temperature variable is

integer array

to be acquired or computed for a grid. Values of 0, 1, or 2 are applicable for

this flag, and have the same meaning as for ITOPTFLG and IPCTLFLG

described above. In contrast to the terrain height data controlled by

ITOPTFLG, however, the strict compatibility between coarse and fine grid

values of sea surface temperature is not required, although it would be rather

senseless for coarse and fine grid values to be grossly different. Sea surface

temperature is a variable defined for each surface grid cell in the model, and

indicates the temperature of any surface water in that cell. For ISSTFLG

set to 2, the model calls subroutine SSTINIT in model file rsurf.f90 that by

default sets the sea surface temperature to the value of namelist variable

SEATMP. If for a fine grid ISSTFLG is set to 0, the sea surface

temperature values for that grid will by default be interpolated from its

parent grid. For ISSTFLG set to 1, values for sea surface temperature are

interpolated from standard RAMS SST data files. This latter option is used

in conjunction with namelist variables ISSTFN. To override any of the

above options, subroutine SFCINIT_USER in the file ruser.f90 is called,

and there a user may customize the sea surface temperature field as

described above for modifying TOPT in subroutine TOPTININT_USER.

IVEGTFLG

Grid-dependent flag specifying how the vegetation type variable is to be

integer array

acquired or defined for a grid. Values of 0, 1, or 2 are applicable for this

flag. If IVEGTFLG is set to 0 (permitted only for a nested grid), values of

vegetation type are directly assigned from the local grid cell of the parent

grid. This applies to each individual subgrid patch as well (see description

of LEAF2 in Section 1c), If IVEGTFLG is set to 1, vegetation class data

are obtained from a RAMS-specific database which is defined globally at

30-arc-second intervals of latitude and longitude, and whose filename prefix

is specified in namelist variable IVEGTFN. When this option is used, and

when IVEGPAT is greater than 1, multiple subgrid land patches are filled

from the RAMS database according to their relative prevalence in the grid

cell. If IVEGTFLG is set to 2, vegetation class values are defined in

subroutine SFCINIT in the rsurf.f90 file. In this latter case, the value

specified in namelist variable NVGCON is used by default for the entire

domain. To override any of the above options, subroutine SFCINIT_USER

in the file ruser.f90 is called, and there a user may customize the vegetation

type field as described above for modifying TOPT in subroutine

TOPTINIT_USER.

ISOILFLG

Flag specifying how soil textural class is to be initialized in RAMS. If

integer array

ISOILFLG = 0 (only allowed for nested grids), soil class is specified from

the local value on its parent grid. If ISOILFLG = 1, soil textural class is

read from standard RAMS data files. If ISOILFLG = 2, soil textural class

for the grid is filled horizontally homogeneously to the value specified by

NSLCON. As for vegetation class values described for IVEGTFLG, soil

textural class values may be customized in subroutine SFCINIT_USER in

the file ruser.f90.

NDVIFLG

Flag specifying how NDVI (Normalized Difference Vegetation Index) is to

integer array

be initialized in RAMS. If NDVIFLG = 0 (only allowed for nested grids),

NDVI is specified from the local value on its parent grid. If NDVIFLG = 1,

NDVI textural class is read from standard RAMS data files. If

NDVIFLG = 2, NDVI for the grid is filled horizontally homogeneously to

the value specified in leaf3_init.f90.As for vegetation class values

described for IVEGTFLG, NDVI values may be customized in subroutine

SFCINIT_USER in the file ruser.f90.

NOFILFLG

Grid-dependent flag similar to ITOPTFLG, ISSTFLG, IVEGTFLG, and

integer array

ISOILFKG, but applies to variables in LEAF2 (the soil, snowcover,

vegetation, and canopy air submodel of RAMS) that are not available on

standard RAMS data files. These variables are: soil temperature, soil

moisture content, snowcover (or temporary surface water) amount,

snowcover temperature, snowcover depth, vegetation temperature,

vegetation surface water, canopy air temperature, and canopy air vapor

mixing ratio. Setting NOFILEFLG to 0 (allowable only for nested grids)

causes initial values of these quantities to be copied from local values on the

parent grid, while setting NOFILFLG to 2 causes the values to be

initialized in a default manner. For default initialization of soil moisture and

temperature, see SLMSTR and STGOFF.Default initial values of

vegetation and canopy air temperatures, and canopy air vapor mixing ratio,

are the values for the lowest model atmospheric layer. Snowcover and

vegetation surface moisture are initialized to zero by default, although

snowcover (ground surface water) is set to a positive value in swamps, bogs,

and marshes where such land surface types are read from the standard

RAMS files (see IVEGTFLG). Note that any of these initial values may be

overridden by modifying subroutine SFCINIT_USER in the file ruser.f90.

This subroutine is often used, for example, to insert soil moisture and

snowcover observational data.

IUPDNDVI

Flag for specifying whether observed NDVI values are to be held constant

integer

in time during a model run (IUPDNDVI = 0) or are to be continually

linearly interpolated in time between the observing times immediately

before and after the current model runtime (IUPDNDVI = 1).

Important: it is strongly recommended the setting IUPDNDVI = 1.

IUPDSST

Flag for specifying whether observed sea surface temperatures are to be held

integer

constant in time during a model run (IUPDSST = 0) or are to be continually

linearly interpolated in time between the observing times immediately

before and after the current model runtime (IUPDSST = 1).

Important: it is strongly recommended the setting IUPDSST = 1.

ITOPTFN

Grid-dependent character variable specifying the name of the terrain height

character array

data header file, with path names if applicable, to be read in conjunction

with namelist variable ITOPTFLG set to 1. These data files are named

according to a convention that identifies the latitude and longitude of their

southwest corners. The standard files prepared for RAMS each comprise an

area of 5 degrees of longitude by 5 degrees of latitude with values defined at

30-arc-second intervals of latitude and longitude, and cover all land areas of

the earth.

These files have names such as EL35N115W, indicating a southwest corner

at 35 degrees north latitude and 115 degrees west longitude, with the

characters 'EL’ serving as a filename prefix for all files in the dataset. The

value specified for ITOPTFN would be 'EL' in this case, as the model

supplies the remainder of the file name according to the file(s) it needs to

read. These terrain height files are written in the same high-information-

density ASCII format as the analysis files (see IOUTPUT). Sometimes in

model applications, fine grids are located within the bounds of a special

limited-area terrain height dataset, such as the one described above, and can

obtain their terrain height information from that dataset, while coarser grids

extend outside the high resolution dataset, and utilize a coarser-resolution

dataset of global coverage, not needing the high resolution data. This is

why ITOPTFN is made grid-dependent.

ISSTFN

Grid-dependent character variable indicating the filename prefix (with path

character array

names if applicable) of the header file for the sea surface temperature data

for initializing each grid. It is similar to namelist variable ITOPTFN.

IVEGTFN

Grid-dependent character variable indicating the name (with path names if

character array

applicable) of the header file for the vegetation type data for initializing

each grid. It is similar to namelist variable ITOPTFN.

ISOILFN

Grid-dependent character variable indicating the name (with path names if

character array

applicable) of the header file for the soil textural class data for initializing

each grid. It is similar to namelist variable ITOPTFN..

NDVIFN

Grid-dependent character variable indicating the name (with path names if

character array

applicable) of the header file for the NDVI data for initializing each grid. It

is similar to namelist variable ITOPTFN.

ITOPSFLG

Flag that controls the type of processing of topographic data from input files

real array

that are specified in ITOPTFN to final values defined on a RAMS grid.

This is a 3-step process that involves topography information being defined

successively on 4 different grids, which we call the ’O’, ‘P’, ‘Q’, and ‘R’

grids. First, a horizontal interpolation is carried out in order to transfer data

from the ‘observed’ or O grid of the input file, to a polar stereographic grid

of comparable resolution, which is our P grid. The P grid uses the same

projection as the RAMS grid (the R grid) where the data will reside in its

final state, but is usually of much higher resolution.

Second, data is averaged from this P grid to a lower-resolution Q grid,

which is also polar stereographic and has a horizontal grid spacing that is an

integer multiple of that on the P grid. This step automatically filters out

small scale variations which are not desired on the model grid (see

TOPENH). In this second averaging step, a choice of averaging algorithms

exists and ITOPSFLG is the flag that selects the choice to be used. If

ITOPSFLG is set to 1, a conventional mean is used where terrain heights

for all P grid cells in a single Q grid cell are summed and divided by that

number of P values, to obtain the value for that Q cell.

For

ITOPSFLG = 1, both the conventional mean and a silhouette average are

computed, and the value assigned to the Q grid cell is a weighted average of

these, with the weights controlled by TOPENH. The silhouette average

finds the mean height of the silhouette, as viewed from the east or west, of

the set of P grid terrain heights contained within a single Q grid cell, and a

separate silhouette height as viewed from the north or south and averages

the two silhouette heights together. This becomes the computed silhouette

height for that coarse-grid cell. While the conventional average preserves

total terrain volume above sea level, the silhouette average adds mass by

filling in valleys. It is used to maintain the effective mean barrier height

that air must rise to when crossing a topographic barrier such as a ridge.

The conventional average lowers this barrier height, particularly when the

barrier height is poorly resolved. When ITOPSFLG = 2, an envelope

topography scheme is used to obtain Q grid values from

P grid values, and this scheme is

an alternative method of attempting to

preserve barrier heights. When

ITOPSFLG = 3, a reflected envelope

topography scheme is used which aims to preserve both barrier heights and

valley depths. Naturally, this method leads to the steepest topography in

RAMS, while still filtering the shortest wavelengths. In the third and final

step, topography is interpolated from the Q grid to the R grid, and the R grid

is usually of moderately higher resolution than the Q grid (see

TOPTWVL).

TOPENH

Grid-dependent variable specifying the weight given to the silhouette

real array

average of terrain height in topographic initialization when ITOPSFLG = 1

(see above), or an envelope orography enhancement factor when

ITOPSFLG = 2 or 3. (Also see TOPTWVL.)

TOPTWVL

Grid-dependent variable specifying the wavelength, in grid-cell size units,

real array

of the smallest horizontal modes of terrain height data which are to be

present on a given model grid. It is applicable only for namelist variable

ITOPTFLG set to 1. Referring to the description of namelist variable

ITOPSFLG above, the value of TOPTWVL controls the ratio of resolution

between the Q and R grids.

The shortest mode which any grid can resolve is that with a wavelength of

twice the grid cell size. In general, the Q grid will contain all wavelengths

of topographic data from its own 2 deltax scale and larger. Hence, if the

RAMS ‘R’ grid, to which data is interpolated from the Q grid, has, for

example, half the cell size of the model grid, the smallest mode that it will

receive from the Q grid will be 4 deltax on the R grid. This smallest mode,

in deltax units of the R grid, is the number specified for TOPTWVL. In

other words, while the R grid spacing is set by the user (see DELTAX), the

Q grid spacing will be TOPTWVL / 2 times the R grid spacing.

This is how smoothing of topographic data is achieved in RAMS while

allowing the variety of enhancing schemes described for ITOPSFLG.

Because the numerical model does not properly handle the smallest modes

resolvable on a grid, it is generally important not to force these modes into

the meteorological fields through overly fine terrain height modes.

IZ0FLG

A flag that controls how surface roughness length is computed for

integer array

computing surface vertical fluxes of momentum, sensible heat, and latent

heat. If IZ0FLG is set to 0, the standard roughness height evaluation of

soil, snowcover, and/or vegetation surfaces is computed in the LEAF-2

submodel of RAMS. If IZ0FLG is set to 1, roughness height is computed

from the roughness of subgrid scale topography, and may reach several

meters. An upper limit to roughness height may be imposed by the user (see

Z0MAX).

The influence of rough topography on vertical turbulent transport is most

properly applied through several (lower) model layers, as well as the surface

itself, but in the current implementation, its effect is concentrated solely on

the surface fluxes. This tends to overestimate fluxes from the soil and

vegetation to the lowest atmospheric level, and this option in RAMS should

be used with caution (also see Z0FACT).

Z0MAX

Upper bound (in meters) imposed on surface roughness height that is

real array

evaluated from subgrid topography (see IZ0FLG and Z0MAX).

Z0FACT

Roughness factor used in computing surface roughness height from subgrid

real array

topography (see IZ0FLG and Z0MAX).

MKCOLTAB

Flag indicating whether or not a collection table is to be created in the

integer

present run. The collection table is required in the bulk microphysics

package, and contains terms derived from the stochastic collection equation.

These terms are computationally intensive to evaluate, and are thus pre-

computed and stored in the collection table where they are efficiently

accessed during model runtime. The values in the table depend on two sets

of parameters. One is the set of gamma distribution shape parameters,

defined in namelist variable GNU. The other is a list of parameters defined

in a data statement in subroutine MICINIT in the file mic_init.f90, which

describe the relation between mass and diameter, and between fall velocity

and diameter for the hydrometeor categories. These latter parameters are

not normally altered, unless a user has reason to change these relationships.

The gamma distribution shape parameters defined in the namelist, however,

are intended to be adjusted and experimented with. Any change in any

parameter of either set requires a different collection table to be created and

used. Setting MKCOLTAB to 1 causes the table to be created at the

beginning of the present run, and to be stored in a file of the name given in

namelist variable COLTABFN. The relevant parameters from both the

namelist (the GNU variable) and the data statement in the code) are written

in the first lines of the collection table. If MKCOLTAB is set to 0, the

model will not create the table, but will instead attempt to read the file

specified in the variable COLTABFN. This option avoids the need to

generate the collection table each time a run is made. When the collection

table is read in, the list of parameters in its first few lines will override the

parameter settings in the namelist and the data statement.

Only relevant for MCPHYS_TYPE = 0

COLTABFN

Is a single-valued character variable giving the name (and path, if any) of

the collection table, described above.

Important:

For MCPHYS_TYPE = 0 the name of the file is “ct2.0”

character

For MCPHYS_TYPE = 1 the name of the file is “col_table”

MAPAOTFILE

Filename to read aerosol optical properties map over South America

Character

(infMapAOT.vfm). Only relevant for the CARMA radiation scheme.

$MODEL_OPTIONS Namelist

The $MODEL_OPTIONS namelist is where the majority of choices for specifying

model parameterization options are made. The variables in this namelist are

those which do not fit under the special categories of the $MODEL_GRIDS and

$MODEL_FILE_INFO namelists, i.e. , those which neither control grid

configuration, space and time domains, nor the reading or writing of data files.

ADVMNT

Flag that controls which advection scheme for scalars will be applied:

Integer

0 = Forward 2nd order (non-monotonic)

Range : 0,1,2

1 = Walcek monotonic advection scheme

2 = hybrid: forward 2nd order for thetail, microphysics species and TKE

and Walcek scheme for tracers.

Option 1 is strongly recommended for chemistry and explicit cloud simulations

GHOSTZONE

Size of the ghostzone for the Walcek advection scheme.

LENGTH

The recommended size is “3”.

Integer

Range: 1 to

max(nxp,nyp)

NADDSC

Grid dependent parameter specifying the number of prognostic scalar fields to be

integer array added to the model simulation. Such scalar fields might be desired by the user for

representing quantities such as chemical or aerosol pollutants. The added scalar

fields are automatically advected, diffused, and marched forward in time, simply by

setting NADDSC to a positive value. The new variable names that are added to

model are SCLP(1), SCLP(2), etc. for the "past' time level and SCLT(1), SCLT(2),

etc. for the tendency arrays. These, therefore, are referenced in the "A' array as

A(ISCLP(1)), A(ISCLP(2)), etc. It is up to the user to add routines in the code to

compute any initialization, source or sink terms required for the added scalars. The

number of scalars that can be added in this way is unlimited (provided computer

memory is large enough), but the value of the parameter MAXSCLR must be

greater than or equal to NADDSC.

ICORFLG

Flag specifying whether the Coriolis force is to be activated, and, if the simulation is

integer

2-D, whether the v-component of velocity is to be activated (0 = no, 1 = yes). In a

2-D simulation where only the u and w velocity components are in the grid plane,

since the v-component would be uncoupled from u and w without Coriolis force, a

value of 0 for ICORFLG deactivates prognosis or use of the v-component. It

should be noted that in a 2-D simulation, which assumes that prognostic fields are

homogeneous in the y-direction, many factors that control the v-component of wind

are excluded from the equation set, and v can become unrealistic, especially where

significant terrain exists in the model domain. Thus, 2d simulations should usually

exclude consideration of the v-component altogether and use ICORFLG = 0. If the

simulation is horizontally homogeneous (namelist variable INITIAL, set to 1), no

horizontal pressure gradients are initially available to balance the Coriolis force, and

it is useful to compute the Coriolis force only from the difference between the

current model winds and a reference state wind (normally the initial model wind

interpolated from the sounding). Then, the true horizontal distribution of pressure

would be regarded as the sum of the prognosed model pressure and a gradient in

geostrophic balance with the reference state wind.

VVELDAMP

Flag that controls if the damping scheme for vertical velocity will be applied or not:

Integer

0 = OFF

Range: 0,1

1 = ON

Option 0 is strongly recommended. Option 1 is useful only for operational purposes.

IEXEV

Flag to determine the type of the Exner function tendency equation to be solved:

Integer

1 = simplest form.

Range: 1,2

2 = complete, mass conservative, solution based on Medvigy et al. (2005) - works

only with sigma-z coordinate.

The recommended option is “2”.

IMASSFLX

Flag to determine if model will output advective and convective mass fluxes for the

Integer

STILT Lagrangian Particle Dispersion Modelling. This option only works with

Range: 0,1

sigma-z coordinate

0 = OFF

1 = ON

IBND

Flag controlling the lateral boundary conditions (in the x-direction) that are applied

integer

on only the coarse grid of a simulation. When IBND = 1, this condition applies only

to the normal velocity component (i.e., U at the east and west boundaries), and

activates the Klemp-Wilhelmson condition in which the normal velocity component

specified at the lateral boundary is effectively advected from the interior assuming a

propagation speed (intended to be similar to a dominant gravity wave phase speed).

This phase speed is specified in the namelist in the variable CPHAS. This boundary

condition is intended to allow most disturbances to propagate out of the model

domain without strongly reflecting back into the interior. Setting IBND to 4 sets up

a cyclic boundary condition between the two x-direction boundaries wherein all

prognostic variables in the model, not just the normal velocity component (u), are

assigned at the boundaries from values taken from the model interior just inside the

opposite boundary. This makes the model periodic in the x-direction, effectively

eliminating lateral boundaries from the solution. The number of grid points in the x-

direction comprising one complete cycle in the periodic field is 3 less than NNXP

for the coarse grid, if the second-order advection scheme is used (see descriptions

for IADVL and IADVF in the ENGPARMS Section). For the 4th- and 6th-order

advection schemes, the periodic cycle length is 5 and 7 points, respectively, less

than NNXP for the coarse grid.

JBND

Similar to IBND, but applies to the y-direction, rather than x-direction boundaries.

integer

In a 2-D simulation, JBND is irrelevant.

CPHAS

Used in conjunction with IBND and/or JBND set to 1, and specifies the

real

characteristic propagation speed of internal gravity waves used in the Klemp-

Wilhelmson lateral boundary condition. A value of 20 m/s is a common setting for

this parameter. Use of larger values, even very much larger, still allows propagation

of gravity waves out of the domain reasonably well, whereas much smaller values

tend to lead to stronger reflection of the waves back into the domain interior. A very

large value of CPHAS is equivalent to the zero-gradient boundary condition.

LSFLG

Complements IBND and JBND as a lateral boundary condition flag, applying to all

integer

variables other than the normal velocity component.

It deals with all these remaining variables in the same way. LSFLG applies only for

IBND = 1 and for JBND = 1. A value of 0 for LSFLG sets the lateral boundary

value of each variable to the value in the field immediately adjacent to the boundary

in the interior. This is a zero-gradient condition. This option is the most commonly

used for horizontally-homogeneous simulations (the INITIAL variable, set to 1),

and is recommended as a first-try option. Occasionally at inflow boundaries, this

zero-gradient option has been found to cause a runaway trend to a field variable, and

must then be replaced by another option. A value of 1 for LSFLG is very similar to

the 0 value, using a zero-gradient condition at inflow boundaries, but setting values

at outflow boundaries such that the second spatial derivative in the direction normal

to the boundary is zero. This is simply an extrapolation from two interior points.

This condition is superior for some cases to the simpler zero-gradient option at the

outflow boundary, but usually makes no significant difference. A value of 2 for

LSFLG is identical with the value of 1 for the outflow boundary condition, but

holds variables constant in time at inflow boundaries. This is a possible remedy to

the runaway problem sometimes encountered at inflow boundaries, as described

above, but is not without its own shortcomings. In cases where flow reverses in

time at a lateral boundary, alternating between inflow and outflow, option 2 for

LSFLG will cause the boundary condition to alternate between constant in time and

time-variant. This may generate an undesirable model response in some cases.

Another problem with holding the variables constant in time at an inflow boundary

is that those constant values are continuously advected into the model interior, and

may become incompatible with the evolving situation in the domain. For example,

if a boundary layer is growing in the model in response to solar heating, the

constant-in-time inflow condition will cause the initial cooler values of temperature

to flow into the model from the boundary, artificially cooling the boundary layer. A

good solution for this situation is to directly specify an appropriate temporal

evolution of the boundary value, still using the LSFLG = 2 option. This is not

presently a standard feature in the code, but can easily be implemented by the user

in subroutine LATSET, located in the file rbnd.f90. A value of 3 for LSFLG leaves

values at all boundaries, inflow and outflow, unchanged in time. This option can be

used only for variable initialization simulations (the INITIAL variable, set to 2),

and has sometimes, but not always, been found to give better results than

LSFLG = 0 for INITIAL = 2.

NFPT

Number of grid levels on the coarse grid, starting from the top of the model domain,

integer

in which the Rayleigh friction absorbing layer will be activated (also see DISTIM).

A value of 0 leaves Rayleigh friction inactive. Rayleigh friction must be applied

only in stable air, and thus requires the model domain to extend sufficiently high,

most commonly in the stratosphere. The bottom layer of the Rayleigh friction zone

should be above the top of whatever meteorological system is important to the

simulation, so as not to directly interfere with its behavior. This normally requires

adding more model levels in the vertical than would otherwise be used in a

simulation not employing Rayleigh friction. Rayleigh friction is a relaxation of all 3

velocity components and potential temperature toward the undisturbed, horizontally

homogeneous reference state values. Its purpose is to damp gravity wave and other

disturbances which approach the top model boundary, so that they will not be

reflected back downward. Because prognostic fields which are not initialized

horizontally homogeneously cannot sensibly be forced toward a horizontally-

homogeneous state, Rayleigh friction must not be used with namelist variable

INITIAL set to 2. However, top boundary nudging (which damps gravity waves)

for horizontally-inhomogeneous initialization may be activated elsewhere (see

TNUDTOP and ZNUDTOP.)

DISTIM

Used in conjunction with namelist variable NFPT in activating Rayleigh friction in

real

the upper region of the model. DISTIM specifies a dissipation time scale in

seconds, representing the e-folding decay time of a disturbance being damped by the

Rayleigh friction layer in the absence of any other source or sink terms. This decay

rate strictly applies at the top boundary of the model only, and the strength of the

damping decreases linearly with height, reaching zero at the lowest of the NFPT

levels in which the damping is activated. DISTIM should be related to the rate at

which the model is generating upward propagating gravity waves, and normally

ranges from 60 to 200 seconds. DISTIM must be at least twice the value of

DTLONG for numerical stability. The model solution proves to be rather

insensitive to DISTIM, provided it is in or near this range.

ISWRTYP

Flag specifying options for evaluating shortwave radiative transfer in the model

Integer

0 = no radiation,

1 = Chen and Cotton parameterization,

2 = Mahrer and Pielke parameterization,

3 = Two-stream parameterization developed by Harrington,

4 = Radiation scheme from the CARMA aerosol model,

5 = reserved,

6 = Rapid Radiative Transfer Model (RRTMG).

The Mahrer and Pielke scheme is the simplest and by far the least expensive

computationally. The main reason for this is that it ignores liquid and ice in the

atmosphere, although it does account for water vapor. This scheme should not be used,

for example, if attenuation of solar radiation by clouds is important to the simulation.

The Chen and Cotton scheme does account or condensate in the atmosphere, but not

whether it is cloud water, rain, or ice. This is a major limitation.

The Harrington parameterization accounts for each form of condensate (cloud water,

rain, pristine ice, snow, aggregates, graupel, and hail) as well as water vapor, and even

utilizes information on ice crystal habit. In addition, the scheme adds upper

atmospheric levels for radiation computation for cases where the model domain does

not extend up to at least 25 km (roughly the height of the ionosphere). This is the most

sophisticated parameterization and is recommended over the Chen and Cotton scheme.

The radiation option 4 is based on the scheme of a modified version of the Community

Aerosol and Radiation Model for Atmosphere (CARMA, Toon et al., 1988). The

original CARMA version considered simultaneously an aerosol microphysics scheme

and two-stream radiative transfer module for both solar and terrestrial spectral regions

(Toon et al., 1989). The major modification from the original version refers to the

prescription of aerosol intensive optical properties, specifically extinction efficiency,

single scattering albedo and asymmetry parameter. These parameters are obtained from

previous off-line Mie calculations. Especially for the South American continent, the

prescription of smoke optical properties derives from the use of climatological size

distribution and complex refractive index from several AERONET sites measurements

in the southern of the Amazon Basin. These properties are used as input to an off-line

Mie code to calculate the spectral optical properties required by CARMA (Procopio et

al., 2003; Rosario et al., 2011). The spatial distribution of the optical models in the

model is based on the concept of anisotropic areas of influence described by

Hoelzemann et al. (2009). Elsewhere in the model domain not covered by the areas of

influence, a reference optical model was adopted.

The option 6 implements the RRTMG radiation scheme. It is a radiative transfer model

that utilizes the correlated-k approach to calculate fluxes and heating rates efficiently

and accurately for application to GCMs. See http://rtweb.aer.com/rrtm_frame.html for

details.

It is strongly recommended to apply options 4 or 6.

ILWRTYP

Similar to ISWRTYP, but applies to longwave, rather than shortwave, radiation.

The same values for ILWRTYP apply with the same meaning as for ISWRTYP.

integer

RADDATFN

Radiation parameterization data file to be read only if CARMA radiation is defined

Character

(ISWRTYP/ ILWRTYP = 4).

RADFRQ

Specifies how often during a model run the radiative parameterization is to be

real

exercised to compute updated values for the radiative contribution to tendencies of

both atmospheric and land surface temperatures. The tendencies themselves are

applied every timestep of the model integration, but the tendencies are updated only

at time intervals specified by RADFRQ. Because computing the radiative

contribution to temperature tendencies is a relatively computationally expensive

process, it is strongly suggested that this computation be done only at intervals of

600 to 1200 seconds (by specifying such values for RADFRQ). In most situations,

this is often enough to account for changes in radiative transfer.

LONRAD

flag specifying whether the longitudinal variation of solar hour angle is to be

integer

accounted for in the computation of shortwave solar radiation, or whether these

angles are to be assumed constant over the model domain. A value of 0 for

LONRAD assumes the hour angle is longitudinally constant, and a value of 1

accounts for its longitudinal variation. The latter choice is the one normally made in

a simulation of a real event, while the former choice is used when a certain level of

idealism is required in a simulation, such as horizontal homogeneity of external

forcing.

NNQPARM

Grid-dependent flag used to control whether the convective parameterization is to

integer array

be activated or not. A value greater than 1 for this flag activates the

Range: 0 to 6

respective parameterization, and a value of 0 leave it inactive. Convective

parameterization is used to vertically redistribute heat and moisture (as if by

convection) in a grid column when the model generates a region which is

superadiabatic or convectively unstable and when the horizontal grid resolution

is too coarse for the model to develop its own convective circulation. Ideally,

resolving a convective circulation would require at least a few grid cells to

horizontally span an updraft, which for deep convection would normally require the

horizontal cell size to be less than 1 or 2 kilometers. Coarser resolution than this

would make realization of sufficiently strong vertical motion difficult or impossible

to adequately bring about the required vertical exchange of heat and moisture so as

to convert the convective available potential energy into other forms. Thus, it is on

coarser grids where a parameterized convective adjustment becomes necessary.

The current parameterizations implement in BRAMS are:

nnqparm= 1- Tremback scheme

nnqparm= 2- Grell-Deveny scheme

nnqparm= 3- Grell-3d formulation

nnqparm= 4- Grell-Freitas scheme as implemented in FIM/NOAA model

nnqparm= 5- Grell-Freitas scale and aerosol aware scheme version 2014

nnqparm= 6- Grell-Freitas scale and aerosol aware scheme version 2015

G3D_SPREAD

Flag to activate the lateral spreading of environmental subsidence in grey zone for

Integer

deep convection applications (grid spacing < 10 km). Only relevant for Grell 3d

Range: 0,1

scheme (NNQPARM =3).

0=OFF, 1=activated

If the Grell’s based parameterization for deep convection is used

CLOSURE_

(NNQPARM>1), this

TYPE

parameter define the type of closure for the parameterization. Setting ‘EN’ defines

character(2)

an ensemble of the closures, which the mass flux is defined by the mean of each

mass flux determined by the closures described below. Setting ‘GR’ would define

the standard Grell closure (quasi-equilibrium assumption). Setting ‘LO’ defines a

closure based on the omega velocity (bar/s) at cloud base. Setting ‘MC’ the closure

will be based on the moisture convergence at atmospheric column. Setting ‘SC’

defines a closure type like Fritsch-Chappel or Kain-Fritsch, in which the instability

is simply removed by convection at some timescale defined in the code. Setting

‘AS’ the scheme will use the Arakawa-Schubert closure. Finally, setting “PB” the

Betchold et al., 2014 closure will be applied.

NNSHCU

Grid-dependent flag used to control whether the Shallow Cumulus parameterization

Integer

is to be activated or not. A value greater than 0 for this flag activates the

Range: 0,1,2,3 parameterization and a value of 0 leaves it inactive.

The shallow scheme available in BRAMS are:

nnshcu= 1- Souza’s scheme

nnshcu= 2- Grell-Deveny scheme

nnshcu= 3- Grell-Freitas scheme

CONFRQ

Time interval in seconds during a simulation at which contributions to atmospheric

real

tendencies in temperature and moisture by convective parameterization are to be

computed. These tendencies are applied to the temperature and moisture fields

every timestep of the model integration, but are updated only at the time interval

specified for CONFRQ. There are two reasons why those contributions should be

updated less frequently than every timestep. One is that a computational expense is

involved in exercising the convective parameterization, and frequent exercise thus

slows down the model. The change in the tendencies would not be large from one

timestep to the next anyway. A second reason has an important physical basis. For

example, consider a case of a squall line moving through a grid volume. As the

squall line enters the grid volume, it will begin to stabilize the air that it has moved

through. However, the air in front of the squall line is still convectively unstable

and will contribute to the maintenance of the squall line. The mean atmosphere i.e. ,

that represented on a coarse grid volume, soon may be stabilized by the convection.

If the convective tendencies were to be re-evaluated in the model each 5 minutes or

so, the result for the above example would be that the original convection might be

shut down in its early stages. A more accurate representation of the squall line,

however, would be to let it run through the entire grid volume. This is achieved by

setting CONFRQ to a time scale comparable to the length of that life cycle, such as

1200 to 1800 seconds. CONFRQ is relevant only if the parameter NNQPARM is

set greater than 0 for a particular grid.

SHCUFRQ

Time interval in seconds during a simulation at which contributions to atmospheric

real

tendencies in temperature and moisture by shallow cumulus parameterization are to

be computed. These tendencies are applied to the temperature and moisture fields

every timestep of the model integration, but are updated only at the time interval

specified for SHCUFRQ. SHCUFRQ is relevant only if the parameter NNSHCU is

set greater than 0 for a particular grid. (Exclusive to BRAMS)

WCLDBS

Use in conjunction with NNQPARM and CONFRQ , and specifies the threshold

real

value of vertical velocity in m/s in the model at the diagnosed level of cloud base

required to initiate convection. The more positive this parameter, the more difficult

is the initiation of convection. Values for this parameter should normally range

from about -0.1 to 0.2. This parameter is relevant only for NNQPARM=1.

NPATCH

Number of subgrid patches used in LEAF-3, which is the RAMS submodel for

energy and moisture in soil, snowcover, vegetation, canopy air, and for surface

integer

fluxes from these and from water surface areas. LEAF2 is described more fully in

section 1c. NPATCH must be at least 2, to allow for water surface areas and at

least one land surface area in each grid cell. Larger values of NPATCH will allow

more land surface areas, each with a different vegetation type, soil textural class,

and/or wetness index. A value of 2 is often used where the extra detail is not

required, while larger values are used for greater accuracy where multiple landuse

types may coexist in the same grid cell or where it is desired to model temperature

and moisture content of individual, varied ecosystems within the same grid cell.

NVEGPAT

Used for any grid whose landuse type is initialized from a standard RAMS file, i.e.,

integer

for which IVEGTFLG = 1. For any surface grid cell, especially one covering a

relatively large geographic area, many landuse vegetation types will often occur in

that area and will be read in from the file. RAMS determines the fractional area of

the surface grid cell that is covered by water (oceans, lakes, rivers) and divides the

land portion of the grid cell among the N most frequently occurring landuse types

read from the file for the cell area, where N is the value specified for NVEGPAT.

NVEGPAT should thus usually be set to NPATCH-1 in order to allow for the 1

water patch and fill all land patches for the data file. For special applications, one

may wish to set NVEGPAT to a value less than NPATCH-1 to reserve additional

land patches for special use. Then, the model will still fill the water patch and the

NVEGPAT land patches such that they collectively comprise the entire grid cell

area. The user must then reduce the fractional areas of 1 or more of the patches to

allow the desired fractional area of the special patch(es) whose number is NPATCH-

NVEGPAT-1. NVEGPAT may not be larger than NPATCH-1.

ISFCL

Flag specifying which of 3 possible options for obtaining surface fluxes of heat and

Integer

moisture to or from the atmosphere will be used in a simulation. If ISFCL is set to

Range: 0, 1, 2 0, the user specifies values for namelist variables DTHCON and DRTCON

and 5.

representing the result of subtracting a fictitious ground temperature and moisture

mixing ratio, respectively, from the surface atmospheric values of the two variables.

These differences are then converted to vertical fluxes of heat and moisture to or

from the lowest atmospheric level. This is the simpler of the 2 choices, and ignores the

LEAF3 parameterization available in the model.

A value of 1 for ISFCL activates the LEAF3 submodel (described in Section 1c).

LEAF3 prognoses soil, vegetation, snowcover, and canopy air temperature and

moisture based on vertical diffusion and exchange with the atmosphere of both

quantities. (Also see NZG, PCTLCON, NSLCON, SOILDZ, SLZ, and STGOFF).

In the current version, SiB submodel is not available. An alternative option is applying

the Joint UK Land Environment Simulator (JULES) model. JULES is a state-of-the-art

land surface model that includes carbon cycle. JULES is activated setting ISFCL = 5

and it has its own namelist “JULES.in”.

NVGCON

Flag specifying the landuse class to be used in the LEAF-3 submodel of RAMS, for

integer

the case where a simple horizontally homogeneous initialization of landuse type is used (see

IVEGTFLG). The landuse class is mostly characterized by its vegetation

type, but landuse class also defines whether the surface is water, ice cap, wetland, or

unvegetated land. By default, the value of this flag is used to fill all surface grid

cells. For horizontally inhomogeneous initialization of landuse type, data are

normally input from a standard dataset (see IVEGTFLG). For direct customizing of

inhomogeneous landuse type, the default homogeneous value specified here may be

overridden in the file ruser.f90. Values for NVGCON ranging from 0 to 30 have the

following definitions in the standard RAMS code, but new classes are easily added

where information is available:

Classes from BATS: 0

Ocean

1 Lakes, rivers, streams (inland water)

2 Ice cap/glacier

3 Evergbreen needleleaf tree

4 Deciduous needleleaf tree

5 Deciduous broadleaf tree

6 Evergreen broadleaf tree

7 Short grass

8 Tall grass

9 Desert

10 Semi-desert

11 Tundra

12 Evergreen shrub

13 Deciduous shrub

14 Mixed woodland

15 Crop/mixed farming

16 Irrigated crop

17 Bog or marsh

Classes from LDAS:

18 Evergreen needleleaf forest

19 Evergreen broadleaf forest

20 Deciduous needleleaf forest

21 Deciduous broadleaf forest

22 Mixed cover

23 Woodland

24 Wooded grassland

25 Closed shrubland

26 Open shrubland

27 Grassland

28 Cropland

29 Bare ground

30 Urban and built up

Each of these landuse classes is assigned a set of land surface parameter (LSP)

values, including leaf area index, vegetation fractional coverage, vegetation height,

albedo, and root depth. The LSP values are defined in a data statement in subroutine

SFCDATA in the file leaf2_init.f90.

PCTLCON

real

Fraction of a surface grid cell, ranging from 0 to 1, that is covered by land surface,

implying that the remainder is covered by water. PCTLCON is the default value

used when IVEGTFLG is set to 2 (see above). If IVEGTFLG is 0 or

1, PCTLCON is ignored. The distinction between land and water surfaces in

the model influences the values of surface fluxes of momentum, heat, and moisture

that are exchanged between the atmosphere and surface. Separate calculations of

these fluxes are made for each grid cell for the soil and water surfaces, and the

resultant net flux is weighted between these two according to the relative area

covered by each type of surface. By default, the value assigned to PCTLCON is

assigned to each surface grid cell in the model. If, as is usually the case, the user

wishes to define a horizontally variable distribution of land percent values,

subroutine SFCINIT_USER in the file ruser.f90 needs to be modified, or land

percentage values can be read in from a standard file (see IPCTLFLG).

NSLCON

Soil textural class used in the LEAF-3 submodel of RAMS. NSLCON is the default

integer

value used when ISOILFLG is set to 2 (see above). If ISOILFLG is set to 0 or 1, PCTLCON is

ignored. The soil type controls important soil properties that

ultimately affect the influence by the soil on the atmosphere. These properties are

the thermal diffusivity, specific heat, moisture capacity (porosity), and the

diffusivity of moisture. The thermal properties are themselves highly influenced by

the moisture content of the soil, but the particular relation between them is

dependent on the soil class. A total of 12 different soil textural classes are

parameterized in the model. The following is a list of each soil class and the value of

NSLCON that activates it:

1 Sand

2 Loamy sand

3 Sandy loam

4 Silt loam

5 Loam

6 Sandy clay loam

7 Silty clay loam

8 Slay loam

9 Sandy clay

10 Silty clay

11 Clay

12 Peat

As in the case for PCTLCON, the value assigned to NSLCON in the namelist is in

turn assigned to the soil type for each surface grid cell in the model. If it is desired to

make the soil type horizontally inhomogeneous, the user may modify subroutine

SFCINIT_USER in the file ruser.f90.

ZROUGH

Roughness length, a parameter important in representing the effects of ground

real

roughness on the surface fluxes of momentum, heat, and moisture. The

parameterization of these fluxes is designed according to surface similarity theory,

in which the roughness length is a crucial parameter. A roughness length of 0.01

meter or less represents a smooth surface, while a roughness length of 1.0 meter

represents a very rough surface such as a forest of tall trees. As in the case of

PCTLCON, the value assigned to ZROUGH in the namelist is in turn assigned to

each grid point in the model. Should the user wish to make roughness length a

location-dependent parameter, subroutine SFCINIT_USER in file rsurf.f90 must be

modified. ZROUGH only refers to the soil areas of the model surface; the

vegetation roughness lengths vary with type and are set in subroutine SFCDATA.

ALBEDO

Albedo or reflectivity of the ground surface to solar radiation. This parameter only

real

applies when the LEAF-3 submodel is not activated, i.e. , for ISFCL set to 0.

In this

case, the albedo is not involved in the computation of surface sensible and latent

heat fluxes; it is only used to compute solar radiation reflected upward from the

ground, which is needed in the atmospheric radiation budget.

SEATMP

Temperature in Kelvin of the surface water temperature. SEATMP is the default

real

value used only if ISSTFLG is set to 2. If ISSTFLG is 0 or 1, SEATMP is

ignored. Horizontally homogeneous initialization of sea surface temperatures by

SEATMP may be overridden by modifying subroutine SFCINIT_USER in the file

ruser.f90. Surface water temperature is relevant for any surface grid cell which is

not completely covered by land (see PCTLCON), and strongly influences the fluxes

of heat and moisture between the surface and atmosphere. If ISSTFLG is 2 and

SEATMP is therefore used, the model assumes that the surface water temperature is

constant in time during a simulation.

DTHCON

Parameter representing the temperature difference in degrees Kelvin obtained by

real

subtracting a fictitious soil temperature from the temperature of the lowest level of

the atmosphere. It is used as a simple means for imposing a surface source or sink

of heat to the atmosphere in the case where the soil model is not activated, that is for

ISFCL set to 0. For example, setting DTHCON to -10 would impose a flux of heat

into the atmosphere equivalent to that which would occur over a ground surface 10

K warmer than the air a height around one half DELTAZ above the ground.

DRTCON

Similar to DTHCON, being relevant only for ISFCL set to 0, but applies to a

real

difference in water vapor mixing ratio, rather than to a temperature difference. For

example, setting DTHCON to -0.002 would cause an upward flux of moisture to the

atmosphere equivalent to that which would occur if the equilibrium vapor mixing

ratio in the soil were 2 grams per kilogram higher than the ambient vapor mixing

ratio at low levels in the atmosphere.

SOIL_MOIS

T

Set the type of soil moisture initialization. If set to ‘n’, initialize with the standard

character(1)

homogeneous soil moisture defined at parameter SLMSTR. If the user desires to

use a heterogeneous soil moisture, defined at a file, it can use one of the possible

options: ‘i’, ‘h’, ‘a’. At any case, the program will initially look for a pre-processed

file defined in USMODEL_IN. If it is not found then it looks for the file defined in

USDATE_IN with the raw data. Setting the parameter to ‘i’, the files defined in

USDATA_IN and USMODEL_IN will be used to define a heterogeneous soil

moisture only when RUNTYPE = 'INITIAL' . Setting to ‘h’, the same will occur

when RUNTYPE = 'HISTORY' only. Setting to ‘a’, both RUNTYPE =

'INITIAL' or ‘HISTORY’ will use the file with heterogeneous soil moisture data.

If the required files are not found, the next parameter SOIL_MOIST_FAIL will

define what to do. (Exclusive to BRAMS)

SOIL_MOIS

T

Define what to do in case of the files defined at USDATA_IN and USMODEL_IN,

_FAIL

necessary if a heterogeneous soil moisture initialization should be used, but are not

character(1)

found. Setting the parameter to ‘s’ would cause a stop in the program. Setting to ‘h’

standard homogeneous soil moisture initialization will be used. Setting ‘l’, the

program will look for until 5 early days, and if they are not found again then the

program will stop. (Exclusive to BRAMS)

USDATA_IN Soil moisture file prefix. This file represents the raw data. If the program only found

character

this file and the file defined in USMODEL_IN do not exist, the file defined in

USMODEL_IN will be generated. (Exclusive to BRAMS)

USMODEL_ Soil moisture file prefix with the soil moisture content interpolated to the grid(s)

IN

model by BRAMS. If this(these) file(s) already exist, the raw data file defined by

character

USDATA_IN no longer needs more. (Exclusive to BRAMS)

SLZ

Depth of the levels in the soil model in meters. There needs to be as many values

real array

specified as NZG beginning with the deepest level. For the SLZ values to be used,

the namelist parameter SOILDZ must be set to 0. The SLZ values pertain to the

bottom of the soil layers. Unlike previous RAMS’ versions, SLZ(NZG) should not be set to 0.

SLMSTR

Used to initialize the moisture content of the soil. The number of values specified

real array

must equal the number of soil levels NZG with the values must be separated by

commas. The first value specified for SLMSTR applies to the deepest soil level,

with the last value representing the topmost layer of soil. Allowable values for this

parameter range from 0.0, representing totally dry soil, to 1.0 which represents

totally saturated soil. A more realistic lower limit is about .15 since soil cannot lose

all of its moisture, even when exposed to direct sunlight for extended periods, and

RAMS will in fact impose a minimum value on soil moisture to prevent its

initialization too dry. The values represent fraction of total water capacity that the

soil can hold. The equilibrium water vapor mixing ratio of the soil is the quantity

with which the ambient atmospheric water vapor mixing ratio interacts in

determining the flux of moisture between the atmosphere and soil. This soil

equilibrium value is a highly nonlinear function of the soil moisture content

(represented initially by SLMSTR). The equilibrium vapor pressure is essentially

constant for soil moisture below about 0.2 and above about 0.7 [depending on the

soil type (see NSLCON)], and varies sharply in between those values. The

SLMSTR values are by default used to fill all soil grid points horizontally-

homogeneously, but horizontal variations in initial soil moisture may be specified by

the user by altering the code in subroutine SFCINIT_USER in the file ruser.f90.

STGOFF

Used to define a vertical temperature profile in the initial conditions for the soil

real array

model, and represents a deviation from the temperature in degrees K in the lowest

atmospheric level in the model. The values must be equal in number to NZG and

must be separated by commas. The first value of STGOFF applies to the deepest

level of soil, while the last value applies to the topmost soil level. For example, if

the first value of STGOFF is set to 5.0, the deepest soil level will initially have a

temperature 5 degrees K. warmer than the initial temperature of the lowest

atmospheric level. As for many other soil variables in the namelist, the values

specified in STGOFF are by default used to horizontally homogeneously initialize

all soil model grid points. A user may impose horizontal variations in the initial soil

temperature by modifying the code in subroutine SFCINIT_USER in model source

code file ruser.f90.

IF_URBAN_

Flag to activate an experimental urban canopy scheme. This scheme currently

requires the pre-computation of drag coefficients defined for a specific urban area.

CANOPY

This scheme was not working properly in the current model version.

integer

IDIFFK

Grid-dependent flag that controls the type of parameterization to be used for computing both

integer

horizontal and vertical diffusion coefficients. Allowable values for this flag are 1, 2, 3, or 4.

array

A value of 1 or 2 is appropriate to model grids in which the horizontal grid spacing is large

compared to the vertical spacing such that dominant convective motions are not resolved.

Range :

Horizontal diffusion in such cases is normally required to be stronger (for numerical

1,2,3,4

damping) than justifiable on physical grounds, and the model assumes complete decoupling

and 7,8.

of the horizontal and vertical diffusion in all aspects, including computation of deformation

rates, length scales, and stress tensor components. With IDIFFK set to either 1 or 2, the

horizontal diffusion coefficients are computed as the product of horizontal deformation rate

(horizontal gradients of horizontal velocity) and a length scale squared, based on the original

Smagorinsky formulation. The length scale is the product of x-direction grid spacing

DELTAX and namelist parameter CSX . When IDIFFK is set to 1, vertical diffusion is

parameterized according to the Mellor and Yamada scheme, which employs a prognostic

turbulent kinetic energy (TKE). When IDIFFK is set to 2, vertical diffusion is computed

from a 1-dimensional analog of the Smagorinsky scheme in which vertical deformation is

evaluated from vertical gradients of horizontal wind, and vertical length scale is the local

vertical grid spacing times namelist parameter CSZ. In addition, modifications of the vertical

diffusion coefficient due to static stability or instability are used, based on formulations of

Hill and Lilly. The Lilly modification is in the form of a multiplying factor, equal to sqrt(1-R

kh/km) where R is the Richardson number and kh/km is the ratio of the scalar to momentum

vertical diffusion coefficients specified by the user in namelist variable ZKHKM . The

multiplying factor is greater than 1 in unstable cases ( i.e. , where wind shear and/or unstable

lapse rates make the Richardson number sufficiently low, and is less than 1 in stable cases.

The Hill modification applies only to regions of unstable lapse rates (having negative

squared Brunt-Vaisala frequencies), and consists of adding the absolute value of the Brunt-

Vaisala frequency squared to the deformation rate, to obtain a modified inverse time scale

for the diffusion coefficient computation. The Lilly and Hill modifications were originally

designed for use without each other, although we have found that the added vertical diffusion

in unstable air obtained by using both together is usually desirable. Values of 3 or 4 for

IDIFFK are usually appropriate on grids having comparable horizontal and vertical

spacings, and are intended for use in situations where dominant 3-dimensional motions, such

as cumulus or boundary layer convection, are resolved. In these cases, RAMS computes

diffusion coefficients from the 3-dimensional rate-of-strain tensor, and uses the same or

similar diffusion coefficients for horizontal and vertical diffusion. When IDIFFK is set to 3,

horizontal and vertical diffusion coefficients are computed as the product of the 3-D rate-of-

strain tensor and a length scale squared. The length scale is the product of the vertical grid

spacing and namelist parameter CSZ. The Hill and Lilly stability-dependent modifications

described above also apply to IDIFFK set to 3. When IDIFFK is set to 4, vertical and

horizontal diffusion are parameterized according to the Deardorff scheme, which employs a

prognostic subgrid turbulent kinetic energy. This scheme is intended only for the specific

purpose of performing a large eddy simulation (LES) in which it is assumed that resolved

eddy motions in the model perform most of the eddy transport. The parameterized diffusion

only represents the subgrid turbulent mixing. Thus, the Deardorff scheme is not appropriate

for horizontal grid cell sizes larger than a couple hundred meters. In both the Deardorff and

Mellor and Yamada schemes, the prognostic kinetic energy is generated by means of shear

and buoyancy processes, and a parameterized pressure-work term, and is destroyed by

potentially all of the above plus a parameterized dissipation term. The kinetic energy is also

advected and diffused. The result of these processes yields a field of kinetic energy from

which the diffusion coefficients are locally diagnosed.

Options 5 and 6 are reserved and must no be applied.

Option 7 activates the Nakanishi and Niino (2004) turbulence scheme. The implementation

is intended to find the TKE tendency by using a 2.5-level model based on Mellor-Yamada

scheme. It's actually an update of the existent M-Y code in RAMS, outputting also the Sig-W

(vertical velocity standard-deviation) and the Lagrangian time scale, Obukhov Length and

PBL depth, the latter following the method by Vogelezang and Holtslag (1996). This option

is required when IMASSFLX is set to 1.

Option 8 activates the Taylor’s theory based formulation for KZZ (Campos Velho, 1998)

CSX

real array

Grid-dependent parameter serving as a coefficient in computing horizontal diffusion

coefficients, in the case where IDIFFK is set to either 1 or 2. It is used in

computing the horizontal diffusive length scale, defined as the product of CSX and

the x-direction grid spacing. Doug Lilly and others have proposed specific values

for CSX based on theory, although the philosophy on which such a theory is based

has been a matter of controversy. Setting CSX to 0.135 is effectively the value

proposed by Lilly to yield diffusion coefficients of a strength that just provides

adequate damping of the smallest resolvable features on the grid (to prevent an

unrealistic accumulation of energy at that small scale). However, justification for a

considerably larger of CSX of 0.32, has been argued by Paul Mason for more

strongly filtering features represented on the grid, so that the only features with

wavelengths longer than about 4 or 5 times the grid spacing will exist at any

significant amplitude on the grid. This choice is desirable since the the smaller

wavelengths of 2 and 3 times the grid spacing are not properly handled by numerical

finite differencing schemes. The price paid for this stronger diffusive filter is the

requirement of more grid cells for simulating a particular feature. The user must

make a judgment here as to how strong to make CSX. This is often done on a case-

by-case basis based on a subjective decision as to whether the model prognostic

fields are "sufficiently smooth' .

CSZ

Similar to CSX, but it applies to the computation of vertical, rather than horizontal,

real array

diffusion coefficients, and is relevant only for IDIFFK set to 2 or 3.

XKHKM

Grid-dependent parameter in which the user specifies the ratio of strength of

real array

horizontal diffusion coefficients between scalars and velocity to be used in a

simulation. It is used to multiply the momentum diffusion coefficient to obtain the

scalar coefficient, and applies to cases where IDIFFK is set to 1 or 2. Deardorff found

that the scalar coefficient had to be around 3 times larger than the momentum

coefficient in strongly convective boundary layers for adequate mixing of all fields. For

stable situations, the ratio may decrease to 1. It has been our usual practice to set

XKHKM to 3, a value which applies throughout the model domain regardless of local

stratification. The Deardorff parameterization for large eddy simulations (activated by

setting IDIFFK to 4) includes an automatic computation of this ratio for each grid cell

in the domain based on the local conditions.

ZKHKM

Similar to XKHKM, but applies to the computation of vertical, rather than

real array

horizontal, diffusion coefficients. It is applicable only in cases where IDIFFK is set

to 2 or 3.

AKMIN

Is a multi-valued, grid-dependent parameter used to impose a minimum value on the

real array

value of the horizontal diffusion coefficients throughout the model domain. It is

only relevant for cases where IDIFFK is set to 1 or 2. The minimum value is

sometimes required when the local fluid deformation rate happens to be close to

zero in a region, resulting in very weak diffusion there. Setting AKMIN to a value

greater than 0 will prevent the horizontal diffusion coefficients everywhere from

falling below the minimum. AKMIN is scaled such that if set to 1.0, the minimum

value placed on the diffusion coefficients should be about the same as normally

obtained from the basic deformation scheme itself (without buoyancy effects)

regardless of grid spacing. It is suggested that AKMIN be set to a low value, say

0.1, so that the standard horizontal diffusion parameterization be given a chance to

do its job. If it is found that horizontal diffusion is inadequate (for example, as seen

by considerable grid noise appearing in a contour plot of model fields), first try

increasing CSX up to as much as .32, and if more diffusion is still required, then

increase AKMIN to as much as 1 or 2, as required.

MCPHYS_TYP Flag that specifies the type cloud microphysics scheme will be applied in the model:

E

0 = previous RAMS/BRAMS version

1 = double-moment from CSU RAMS version 6.0+ and aerossol aware

Integer

Range: 0 to 3 2 = Thompson cloud water single-moment

3 = Thompson cloud water double-moment and aerossol aware

Important: all microphysics flags below are relevant only for mcphys_type = 0 or 1.

LEVEL

Flag that specifies the level of moisture complexity to be activated in the model. This flag

integer

is the primary means by which the user tells the model whether to consider the effects of

moisture in the simulation, and if so, to what degree.

LEVEL = 0 - causes the model to run dry, completely eliminating any process which

influences or is influenced by any phase of moisture. With this option, radiation

parameterizations (controlled by ISWRTYP and ILWRTYP) must be turned off.

LEVEL = 1 - activates advection, diffusion, and surface flux of water, where all water

substance in the atmosphere is assumed to occur as vapor even if supersaturation occurs.

The value of 1 also activates the buoyancy effect of water vapor in the vertical equation of

motion, as well as the radiative effects of water vapor if radiation is activated elsewhere.

LEVEL = 2 - activates condensation of water vapor to cloud water wherever

supersaturation is attained. The partitioning of the total water substance into vapor and

cloud water is purely diagnostic in this case. No other forms of liquid or ice water are

considered. Both the positive buoyancy effect of water vapor and the liquid water loading

of cloud water are included in the vertical equation of motion. Radiative effects of both

water vapor and cloud water are activated, if the radiation parameterization is itself

activated.

LEVEL = 3 - activates the bulk microphysics parameterization, which includes cloud

water, drizzle, rain, pristine ice, snow, aggregates, graupel, and hail, or certain subsets of

these as specified by ICLOUD, IDRIZ, IRAIN, IPRIS, ISNOW, IAGGR, IGRAUP, and

IHAIL. This parameterization includes the precipitation process.

IRIME

Choice of standard bulk riming (IRIME=0) or hybrid-bin riming of cloud droplets via

integer

method of moments (IRIME=1). (Saleeby and Cotton 2008, JAMC).

IPLAWS

IPLAWS=0 uses original hydrometeor species fall speed power laws from RAMS 4.3.

integer

IPLAWS=1 uses non-banded, but newer power laws via Mitchell (1996). IPLAWS=2

uses size banded newer power laws via Mitchell (1996) and modified by Rob Carver and

Jerry Harrington (PSU).

ICLOUD

Is similar to IRAIN, but applies to the cloud water category. In RAMS version 4.3,

integer

prediction of cloud droplet number concentration is not implemented, so ICLOUD must

be less than 5. Values of 1 or 4 are normally very preferable over

ICLOUD = 2. In RAMS version 4.4, cloud droplet number prediction is an option, and is

used by setting ICLOUD to 5, 6 or 7. ICLOUD = 5 nucleates cloud droplets from a

constant concentration of cloud condensation nuclei (CCN). ICLOUD = 6 nucleates

cloud droplets from CCN in which exponential decrease with height. When ICLOUD is

set to 7, a three-dimensional CCN field must be set in mic_init.f90. The CCN field is

initialized by default from the concentration specified in CPARM (see below) in units of

#/cm3. Aerosols evolve in time after initiation. ICLOUD is relevant only when LEVEL

is set to 3.

IDRIZ

Similar to ICLOUD, but controls the activation of drizzle rather than cloud. IDRIZ

integer

cannot = 5 unless ICLOUD=5. If IDRIZ > 0, then cloud droplets generally pass through

the drizzle mode during growth before becoming rain. This slows autoconversion a bit.

If IDRIZ = 5, then aerosols can nucleate directly to the drizzle mode if the median radius

of the activated aerosol distribution > ~1.0 microns.

IRAIN

Flag that controls the model's treatment of rain water, and is relevant only if

Integer

LEVEL is set to 3. If IRAIN is set to 0, rain is not activated, and any process involving

the interaction of rain with other water species is not performed. Rain is activated when

IRAIN is set to a value from 1 to 5. Activation means that the mixing ratio of rain is

prognosed from conservation equations which include advective, diffusive, and

precipitation tendencies, and source terms resulting from interactions between rain and

other forms of water substance. The choice of values for IRAIN between 1 and 5

controls the manner in which the mean rain droplet diameter and number concentration

are determined. With the flag equal to 1, the mean diameter is specified from a default

value in the code, and the number concentration is diagnosed automatically from this

mean diameter and the prognosed mixing ratio. When the flag is set to 2, the user

specifies the mean diameter (in meters) in the namelist variable RPARM, and the

number concentration is diagnosed as before. When the flag is set to 3, the user specifies

the y-intercept value of the number concentration (this is the number concentration per

unit diameter increment, (i.e., number per m^3 per m), evaluated at zero diameter,

assuming a Marshall-Palmer (exponential) size distribution. The total number

concentration (i.e., the total number of droplets per cubic meter) and the mean diameter

are then both diagnosed from the y-intercept value and the prognosed mixing ratio. With

a value of 4 for the flag, the user specifies the total number concentration of rain droplets

(number per kg of air) directly in the namelist variable RPARM, and the mean diameter

is automatically diagnosed from this concentration and the prognosed mixing ratio.

When the flag is set to 5, the model activates a prognostic equation for rain droplet

number concentration, and a special array for this quantity is added. Mean rain droplet

diameter is then diagnosed from the prognosed mixing ratio and number concentration.

Note that if any of the flags IRAIN, ISNOW, IAGGR, IGRAUP, or IHAIL is set to 5,

the model will override settings of 1, 2, 3, or 4 for ALL of the others and make them 5.

(Any that are set to zero will remain zero.) Thus, the model requires that if number

concentration is predicted for any of these, it must be predicted for all of these species

that are active. IPRIS is not in this list; it must ALWAYS be set to 5 (if pristine ice is

activated). Independently of how flags for the other species are set. The choice of which

value of IRAIN to use will depend to a large extent on how the user wishes to constrain

the rain field, i.e., whether mean diameter, total number concentration, or both should be

allowed to vary. For example, if the user is simulating an observed and documented

precipitation event in which, say, mean droplet diameter was measured, it would make

sense to specify that diameter as a fixed quantity. Independent selection of microphysical

species to be activated versus not activated is controlled through the setting of IRAIN

and the related parameters IPRIS, ISNOW, IAGGR, IGRAUP, and IHAIL described

below. However, not all possible combinations are intended as valid nor would they

function properly without code modification. Activation of all categories simultaneously

is the normal practice, although activation of the limited sets {cloud}, {cloud, rain},

{cloud, pristine ice}, {pristine ice}, {pristine ice, snow}, {pristine ice, aggregates}, and

{pristine ice, snow, aggregates} are reasonable when only a limited range of

microphysical processes need to be considered.

IPRIS

integer

Similar to IRAIN, but controls the activation of pristine ice rather than rain. The

descriptions of the various settings given for IRAIN apply here, except that if pristine ice

is activated at all its number concentration must be predicted as well. Hence, values of 1,

2, 3, and 4 are not permitted for IPRIS. With IPRIS = 5, BRAMS assumes that ice

forming nuclei (IFN) have its concentration initially based on PPARM.

ISNOW

Similar to IRAIN, but controls the activation of snow rather than rain.

The

integer

descriptions of the various settings given for IRAIN apply here.

IAGGR

Similar to IRAIN, but controls the activation of aggregates rather than rain.

The

integer

descriptions of the various settings given for IRAIN apply here.

IGRAUP

Similar to IRAIN, but controls the activation of graupel rather than rain. The

integer

descriptions of the various settings given for IRAIN apply here.

IHAIL

Similar to IRAIN, but controls the activation of hail rather than rain.

The

integer

descriptions of the various settings given for IRAIN apply here.

ICCNLEV

integer

Flag for aerosol treatment complexity. First note that when multiple aerosol categories

are turned on, they will compete for nucleation based on the surface area of the fraction

of particles that may nucleate. (see Saleeby and van den Heever 2013, JAMC)

ICCNLEV=0 allows aerosol activation for nucleation but only nucleates additional

aerosol in excess of the number of cloud droplets present in a given grid cell. Aerosols

are not removed from the domain by nucleation. ICCNLEV=1 allows aerosol removal

upon nucleation of new cloud droplets. Removal from each category starts at the large

end of the distribution first. Largest aerosols are removed first and the median radius is

then recalculated before the next timestep and will be smaller since the larger aerosols

were removed. ICCNLEV=2 is the same as ICCNLEV=1 but now we store the

nucleated and removed aerosol mass in tracking arrays. A tracking array exists for each

hydrometeor species. First, aerosol mass will enter the cloud category tracking array.

As cloud is collected or undergoes any transfer to another category, a proportional

amount of aerosol mass-within-cloud will be transferred as well. All possible transfers

among hydrometeor species is accounted for. Upon hydrometeor evaporation, aerosols

will be restored to a regenerated aerosol category. For regeneration, the mass of

regenerated aerosols is proportional to the mass of evaporated hydrometeor mass. The

number of restored aerosols equals the number of fully evaporated hydrometeors in

each category. If the median radius of the regenerated aerosols is < 1 micron, then the

aerosols enter the sub-micron regenerated category. If > 1 micron, they enter the super-

micron regenerated category. NOTE: ICCNLEV=2 will function for single moment

microphysics (except ICLOUD must = 5) but any regeneration will be suspect since

number concentration may be diagnosed rather than predicted. This could lead to

regeneration of unrealistic numbers of aerosols.

Similar to RPARM below, but applies to cloud water rather than rain. If ICLOUD is set

to 5 (see above), CPARM represents the concentration of cloud concentration nuclei

(CCN) in number per kilogram of air. If ICLOUD is set to 7, a prognostic CCN field is

activated in RAMS, and CPARM then represents the initial value (in number per

CPARM

kilogram of air) of the CCN concentration field.

Similar to RPARM below, but applies to cloud water rather than rain. If ICLOUD is set

to 5 (see above), CPARM represents the concentration of cloud concentration nuclei

(CCN) in number per kilogram of air. If ICLOUD is set to 7, a prognostic CCN field is

activated in RAMS, and CPARM then represents the initial value (in number per

real

kilogram of air) of the CCN concentration field.

Similar to RPARM, but applies to drizzle rather than rain. DPARM is linked to giant

cloud condensation nuclei (GCCN) as CPARM is linked to CCN when IDRIZ is set to

DPARM

5, 6 or 7.

real

RPARM

Specifies either a fixed mean diameter (in meters), a fixed y-intercept number

real

concentration per unit diameter increment (number per m^3 per meter), or a fixed

total number concentration (in number per kg of air) to be imposed on the rain

droplet field, in conjunction with settings 2, 3, and 4, respectively, for the flag

IRAIN described above. If IRAIN is set to 0, 1, or 5, RPARM is ignored.

Obsolete as pristine spectrum parameter (mean diameter, y-intercept number

concentration or total number concentration) since pristine ice number concentration

must always be prognosed (IPRIS = 5). PPARM is an initialization parameter for ice

forming nuclei (IFN) concentration. IFN is a prognostic variable.

PPARM

real

SPARM

Similar to RPARM, but applies to snow rather than rain.

real

APARM

Similar to RPARM, but applies to aggregates rather than rain.

real

GPARM

Similar to RPARM, but applies to graupel rather than rain.

real

HPARM

Similar to RPARM, but applies to hail rather than rain.

real

CNPARM

Median radius of the CCN spectrum in terms of distribution (cm)

real

GNPARM

Median radius of the GCCN spectrum in terms of distribution (cm)

real

EPSIL

Aerosol solubility fraction (0 to 1)

real

GNU

Parameter with 8 values, one for each hydrometeor category. It specifies the shape

real array

parameter of the gamma distribution that all categories in the bulk microphysics

submodel are assumed to follow. GNU = 1 indicates the Marshall-Palmer, or

exponential, distribution, in which number concentration decreases monotonically

with diameter throughout the size spectrum. Larger values of GNU indicate more

general gamma distributions, in which the size distribution peaks at a positive

diameter. The larger the value of GNU, the more narrowly distributed the spectrum

is. The intent in using this variable is to specify a shape based on observation. The

shape may in general depend on the type of precipitating system (deep convective,

wintertime cyclone, etc.), as well as on the hydrometeor category (rain versus hail,

for example). Little observational guidance is available to date on appropriate values

of GNU. A Marshall Palmer distribution has been used in many models, although it

may not be the closest of the gamma distribution family to real hydrometeor spectra.

Sensitivity experiments with GNU in RAMS have demonstrated that it can

sometimes have a significant effect on model results. The user is encouraged to

experiment with the values of GNU, and to use observational guidance where

possible. Ongoing research is aimed at determining appropriate values of GNU for

each hydrometeor category in different weather situations. Values of 2 are suggested

as middle-of-the-road values to start from, but it is sometimes argued that cloud

spectra are generally narrower and should have gnu equal to at least 5.

$MODEL_SOUND Namelist

The $MODEL_SOUND namelist consists of a set of variables for specifying a sounding

to be used in initializing a simulation. This method of initialization is performed

horizontally homogeneously, and is performed only when the flag INITIAL is set to 1.

The variables in the $MODEL_SOUND namelist consist mainly of (1) arrays

containing the actual values of pressure or height, velocity, temperature, and moisture,

and (2) a set of flags specifying how the array values are to be interpreted. An alternative

form of specifying five of the variables in this namelist, PS, TS, RTS, US, and VS, all described below, is to enter them into a file called SOUND_IN in tabular form. This

option is selected by setting the first value of PS to 0. In this case, the model opens and

reads the file SOUND_IN, which must reside in the same directory as the model

executable. The code that reads from this file is contained in the file rhhi.f90 in

subroutine ARRSND in the first DO loop. Free format is assumed with one sounding

level per record starting with the lowest sounding level at the top of the file, and the five

variables are read from each record in the order shown above.

Variable

Description

name

IPSFLG

Is a flag specifying how the values given for PS are to be interpreted. When

integer

IPSFLG is set to 0, all values in PS are interpreted as pressures in millibars, and

when IPSFLG is set to 1, all values in PS are interpreted as heights in meters. In

either case, the PS values are used to define the heights in the sounding at which all

sounding data applies.

ITSFLG

Is a flag specifying how the values given for TS are to be interpreted. When

integer

ITSFLG is set to 0, all values in TS are interpreted as temperatures in degrees C,

when ITSFLG is set to 1, all values in TS are interpreted as temperatures in degrees

K, and when ITSFLG is set to 2, all values in TS are interpreted as potential

temperatures in degrees K. The options allow the model to read sounding

temperature data in any of these forms.

IRTSFLG

Flag specifying how the values given for RTS are to be interpreted.

When

integer

IRTSFLG is set to 0, all values in RTS are interpreted as dew point temperatures in

degrees C, when IRTSFLG is set to 1, all values in RTS are interpreted as dew

point temperatures in degrees K, when IRTSFLG is set to 2, all values in RTS are

interpreted as water mixing ratio values in grams per kilogram, when IRTSFLG is

set to 3, all values in RTS are interpreted as relative humidities in percentage, and if

IRTSFLG is set to 4, all values in RTS are interpreted as dew point depressions in

degrees K. The options allow the model to read sounding moisture data in any of

these forms.

IUSFLG

Flag specifying how the values given for US and VS or for USNDG and VSNDG

integer

are to be interpreted. When IUSFLG is set to 0, all values in US (or USNDG) are

interpreted as components of velocity in meters per second in the x-direction, and all

values in VS (or VSNDG) are interpreted as components of velocity in meters per

second in the y-direction. When IUSFLG is set to 1, all values in US (or USNDG)

are interpreted as wind directions in degrees azimuth clockwise from true north, and

all values in VS (or VSNDG) are interpreted as wind speeds in meters per second in

the x-direction.

HS

Sounding heights, but only the first value is read from the namelist. This first value

real array

indicates the absolute height (relative to sea level) of the first or lowest sounding

level. It must be at or below the lowest topography height in the RAMS model

domain. This may require adding one or more levels to the bottom of a real

sounding.

PS

Pressures in millibars or the heights in meters of the sounding levels starting at the

real array

ground and proceeding upward. The choice of meaning is controlled by the value of

IPSFLG. If PS represents heights, the first value of PS is still specified as a

pressure in millibars, and its corresponding height is read from namelist variable

HS. The primary requirement of the sounding data is that it extend to a height

greater than the top of the model domain, and at least as low as the lowest

topography in the domain. Thus, the top sounding level must contain either a height

or a pressure higher in the atmosphere than the model domain top, which is itself

determined by the combination of namelist parameters NNZP, DELTAZ, DZRAT,

and DZMAX, or by ZZ. A maximum of 200 values may be specified for PS,

although with code modification this number could be increased if necessary. The

values given for PS will determine the vertical spatial resolution of the sounding,

and should be chosen to properly represent any important significant levels. Note

the special option of setting the first value of PS to 0., as described at the

beginning of this Section.

TS

Sounding temperature values. The way

in which the values are interpreted is

real array

specified by namelist variable ITSFLG.

The number of values specified for TS

must equal the number of values specified for PS. The user should use caution in

specifying sounding temperatures. Superadiabatic profiles in the sounding are

strongly discouraged (which does not mean that the model simulation may not

successfully develop superadiabatic regions after initialization). High vertical

resolution is sometimes desirable in a sounding because the model fields of

temperature and moisture mixing ratio are interpolated linearly from it in the vertical

direction, and relative humidity is a very nonlinear function of these two

interpolated fields. This can result in supersaturated layers in the model initial fields

where none exist in the sounding.

RTS

Sounding moisture values. The way in which the values are interpreted is specified

real array

by namelist variable IRTSFLG. The number of values specified for RTS must

equal the number of values specified for PS. (Also see TS.)

US

Sounding wind values. The way in which the values are interpreted is specified by

real array

namelist variable IUSFLG. The number of values specified for US must equal the

number of values specified for PS.

VS

Sounding winds values. The way in which the values are interpreted is specified by

real array

namelist variable IUSFLG. The number of values specified for VS must equal the

number of values specified for PS.

$MODEL_PRINT Namelist

The $MODEL_PRINT namelist provides a means for obtaining a quick look at model

fields. It is used to specify selected data from the model to be written to the standard

output file generated with a model run. This data is then examined by displaying the

contents of the standard output file.

Variable

Description

name

NPLT

Total number of data subsets to be written to the standard output file. Most of these

integer

data subsets consist of a 2-D cross section of values from a 3-D model field.

Different cross sections from the same model field are considered as separate data

subsets. (If the model itself is run in 2-D, the 2-D cross section normally

encompasses the entire model domain.) The exact specification of the cross section

to be output is made in namelist variables IPLFLD, IXSCTN, and ISBVAL. Fields

from the LEAF2 submodel of RAMS are output in their entirety rather than as a

specified 2-D slab.

IPLFLD

Variables to be written to the standard output file. Each value specified for

character array IPLFLD must be followed by a comma, and the total number of values specified

must be at least the value specified for NPLT. The authentic complete list of

character strings that can be used as values for IPLFLD is provided in FUNCTION

OPTLIB and in subroutine SFCPRT located in the file rprnt.f90. Other choices are

easily added to OPTLIB.

PLFMT

FORTRAN format to be used in writing a data subset (see NPLT) to the standard

character array output file. Although a default format exists in the model for every field variable,

defining alternative formats in PLFMT is a way of overriding the default when

necessary. Any element of PLFMT that the user wishes to define a value for is

listed individually. We illustrate the use of this variable by means of the following

example: PLFMT(2) = '3PF6.1'. The subscript 2, denoting the second element in

the PLFMT array, corresponds to the second element specified in the IPLFLD

array. The character string assigned to PLFMT(2) denotes the format to be used in

writing that second field in IPLFLD. The format statement itself contains the F6.1

part referring to the well-known floating point format, and the less-well-known 3P

part which scales (multiplies) each value by 10**3 before writing it. This latter

feature is sometimes necessary when values in a given field become unusually large

or small, and are thus incompatible with the default format. For example, the

default format for vertical velocity involves a multiplication of the model values by

100 so that output values are expressed in cm/sec. This is usually best for mesoscale

simulations, but not appropriate for simulations of deep convection which generate

vertical velocities of tens of meters per second.

IXSCTN

Controls the orientation of the 2-D cross section extracted from the given model

integer array

field for writing to the standard output file. A value of 1 for IXSCTN specifies the

data subset to be an X-Z cross section, a value of 2 denotes a Y-Z cross section, and

a value of 3 denotes an X-Y cross section. Fields from the LEAF2 submodel of

RAMS (IPLFLD = ‘TGP’, ‘TGPT’, ‘WGP’, ‘SCHAR’, or ‘GSF’) are output in

their entirety. Each element in the IXSCTN array refers to the corresponding

element in the IPLFLD and ISBVAL arrays. A number of values equal to or

greater than NPLT must be specified.

ISBVAL

Selects a specific 2-D slab from a 3-D model field among all slabs having the

integer

orientation specified by IXSCTN. Each number specified for IXSCTN refers to the

array

grid location index in the direction perpendicular to the slab, with the value 1

denoting either the westernmost, the southernmost, or the lowest slab, depending on

the orientation. Each element in the IXSCTN array refers to the corresponding

element in the IPLFLD and IXSCTN arrays. A number of values equal to or greater

than NPLT must be specified.

RAMS ISAN Configuration Parameters – Fortran 90 Module:

“isan_coms .f90”

The following configuration parameters are defined in the isan_coms.f90 file

(encountered at <BRAMS_ROOT_DIRECTORY>/src/brams/modules/). They function

as dimensions for several arrays and are responsible for the maximum values that can be

set for some namelist variables during execution. These are mentioned for completeness

and would not normally need to be changed except in extreme circumstances. They may

be set to fairly large values in a standard model installation, as their settings do not affect

total memory usage very much; most of the memory is allocated dynamically. Note that

an index of configuration and namelist variables for chapters 6, 7, and 8 is located at the

end of chapter 8.

MAXPR

Maximum number of vertical levels that can be used in the pressure data.

integer

MAXISN

Maximum number of vertical levels that can be used in the isentropic analysis.

integer

MAXX

Maximum number of grid points (in the "x'' or east-west direction) in any of the

integer

RAMS or pressure grids.

MAXY

Maximum number of grid points (in the "y' or north-south direction) in any of the

integer

RAMS or pressure grids.

MAXTIMES

Maximum number of data analysis times that can be processed in a single run.

integer

MAXAGRDS

Maximum number of RAMS grids that can have varfiles generated.

integer

MAXSIGZ

Maximum number of vertical levels that can be used in the σ_z analysis.

integer

MAXLEV

Maximum number of levels in an input rawinsonde.

integer

MAXSNAME

Maximum number of input observations

MAXISFILES

Maximum number of input data times

RAMS ISAN Namelists

Variable

Description

name

ISZSTAGE

Switch with a value of 0 (no) or 1 (yes), indicating whether the isentropic/σz stage of

integer

ISAN is to be run. This stage inputs observational upper air datasets, as prepared

separately in ‘RALPH2 format’ and objectively analyzes the data onto both

isentropic and σz surfaces. It also inputs surface observations and

objectively analyzes them onto a surface that is itself an objectively analyzed height

surface based on surface elevations of the surface stations. This stage and the

subsequent ‘varfile’ stage (see IVRSTAGE) can be run at once or each can be

executed individually. The isentropic stage outputs the isentropic and σz files which

the varfile stage will input if run separately.

IVRSTAGE

Similar to ISZSTAGE (see above) but applies to the ‘varfile’ stage, which produces

integer

varfiles for model initialization from isentropic and σz fields generated by the

isentropic/σz stage of ISAN. (Also see

ISAN_INC

Desired interval between consecutive data processing times. Certain files may be

integer

available at more frequent times than others, as, for example, surface observations in

contrast with rawinsonde observations. Setting ISAN_INC to the standard 12-hour

interval between rawinsondes will cause surface observations to be processed at

only the rawinsonde times. The beginning and duration of the time period to

processes observational data are specified in IYEAR1, IMONTH1, IDATE1,

ITIME1, and TIMMAX in the $GRIDS namelist. The format for ISAN_INC is

hhmm.

GUESS1ST

Set to ‘PRESS’ or to ‘RAMS’ to specify whether the first guess field in the objective

character

analysis of observational data is to be interpolated from pressure level data or taken

from a RAMS analysis file.

I1ST_FLG

What choice the model should make if the first guess field is not found but was

integer

requested to be used. This situation may arise, for example, in an operational setting

where observational data are expected periodically from an outside source, but

where something has prevented the data from being available. If I1ST_FLG is set

to 1, it instructs ISAN to skip all processing of this data time and proceed with the

next time. This will result in a particular varfile not being generated. If I1ST_FLG

is set to 2, it instructs ISAN to stop. IF I1ST_FLG is set to 3, it instructs ISAN to

generate a first guess field by interpolating between the previous and next available

data times. If either expected datafile likewise does not exist, ISAN will stop.

I1ST_FLG = 3 is not implemented yet.

IUPA_FLG

Similar to I1ST_FLG, but applies to input rawinsonde data instead of the first guess

integer

field. Another difference: if IUPA_FLG is set to 3, ISAN is instructed to process

the given data time without rawinsonde data.

ISFC_FLG

Similar to I1ST_FLG, but applies to input surface data instead of the first guess

integer

field. Another difference: If ISFC_FLG is set to 3, ISAN is instructed to process

the given data time without surface data.

IAPR

Filename prefix, with directory path if applicable, of the input pressure files that

character

were generated by dataprep. All files that have this prefix (and that are within the

specified processing parameters) will be processed.

IARAWI

Filename prefix, with directory path if applicable, of the input rawinsonde files that

character

were generated by dataprep. All files that have this prefix (and that are within the

specified processing parameters) will be processed.

IASRFCE

Filename prefix, with directory path if applicable, of the input surface observation

character

files that were generated by dataprep. All files that have this prefix (and that are

within the specified processing parameters) will be processed.

VARPFX

Filename prefix, with directory path if applicable, of two classes of files that are

character

output from ISAN. The first file type is the ‘varfile’, which is the final stage of

processing by ISAN and contains velocity, pressure, potential temperature, and

vapor mixing ratio fields interpolated to the model grid(s) and ready for

initialization and/or time-dependent data assimilation. The other file type is the

‘isentropic/σz file’, which contains the output from the isentropic, σz, and surface

analyses that are performed before the varfile stage of ISAN (see ISZSTAGE).

While both file types are assigned names that begin with the prefix plus the year,

month, date, and time automatically appended, the varfile name is additionally given

a ‘V’ character, while the isentropic/σz file name is given an ‘I’ character. One run

of ISAN may process data at one or many analysis times, and files for all times are

named with the same prefix but different time designations.

IOFLGISZ

Flag indicating whether to write out the isentropic/σz files: 0 – no, 1 – yes. (See

character

ISZSTAGE and VARPFX).

IOFLGVAR

Flag indicating whether to write out the varfiles: 0 – no, 1 – yes. (See ISZSTAGE

character

and VARPFX).

$ISAN_ISENTROPIC Namelist - ISAN Isentropic/σz Stage

Variable

Description

name

NISN

Number of isentropic levels on which to perform objective analysis. A value around

integer

40 is suggested for NISN to provide adequate vertical resolution.

LEVTH

Isentropic levels in integer degrees Kelvin of the isentropic grid on which objective

integer array

analysis is performed.

The spacing that normally provides sufficient vertical

resolution is 1-2 K near the ground, 3-5 K in the remainder of the troposphere, 20-30

K in the lower stratosphere, and 50 K in the middle stratosphere. It is now common

practice in RAMS to use the NCEP reanalysis pressure level data as the first guess

field in RAMS, and the top level of this dataset is 10 mb. Thus, isentropic levels

may be specified to values as high as 800 K, in case the model domain is unusually

high.

NIGRIDS

Number of RAMS grids to analyze. This must be less than or equal to NGRIDS in

integer

the $MODEL_GRIDS namelist. Although the ability exists to analyze atmospheric

data and generate a varfile independently for each RAMS grid, this option does not

yet produce analyses that match smoothly across nested grid boundaries. Thus

varfiles for nested grids should be used only for model initialization and not 4DDA

(Newtonian nudging during model runtime) (see TNUDCENT). Gradients of

prognostic variables initialized at grid boundaries will tend to weaken with time if

they are not continuously restored by nudging.

TOPSIGZ

σz analysis will be done to all model levels under this height (in meters).

real

HYBBOT

The hybrid analysis between the isentropic and σz datasets is accomplished in this

real

version of ISAN by a weighted blending of the data over a specified, terrain-

following layer using a linear (in height above the surface) weighting profile. At the

bottom of the layer, the data is completely from the σz analysis; at the top of the

layer, the data is completely from the isentropic analysis. HYBBOT is the

approximate height above the surface of the bottom of this layer. The actual bottom

is found as the closest model level to HYBBOT.

HYBTOP

Approximate height above the surface of the top of the isentropic/σz blending layer

real

(see HYBBOT above).

The actual height of the top is found as the closest model

level to HYBTOP.

SFCINF

In addition to the blending of the isentropic and σz analysis in the creation of the

real

varfile, the surface data analysis is also blended in a layer near the ground. This

only occurs if there are actual surface observations close enough to a grid point and

the model level is within a certain vertical distance from the actual station height.

This distance is SFCINF (meters). The actual weight given to the surface analysis

varies from a full weight if the difference between the model level and station height

is 0. to no weight for the surface (full weight for the upper air data) when the

difference reaches SFCINF.

SIGZWT Optional weight given to the σz analysis in the blending process. If SIGZWT is set

real to 0., then the varfile will only contain information from the isentropic analysis. If

SIGZWT is set to 1., then the varfile will contain full information from the σz analysis under HYBBOT. Any value between 0. and 1. may be used. For most

applications, this should be set to 1.

NFEEDVAR

In the creation of the varfiles when more than one grid is analyzed, the data can

integer

optionally go through the nesting "feed back'' process. The feed back must be done

if the 4-dimensional data assimilation options are to be used. Set NFEEDVAR to 1

to do the feed back. Set NFEEDVAR to 0 usually only if you are doing a data

analysis on different grid resolutions, will not be running the model, and you want to

see the unmodified results of the different resolution analyses. Normally, leave this

set to 1.

MAXSTA

Maximum number of rawinsondes expected in the data access.

Memory will be

integer

allocated using this number, so don't set it too big.

MAXSFC

Maximum number of surface observations expected in the data access. Memory

integer

will be allocated using this number, so don't set it too big.

NOTSTA

Number of stations in the domain area to be excluded if they are found. The specific

integer

stations to be excluded are indicated by NOTID (see below). Excluding stations in

this way is the means for eliminating stations with bad data.

NOTID

Station IDs to be excluded from any further processing (see NOTSTA above).

character

array

Prefix the station ID with an 'r' for rawinsonde or an 's' for surface observation.

STASEP

Surface observations will be objectively analyzed with the Barnes scheme that

real

assumes uniform data coverage. Frequently, there are 2 surface stations reporting in

the same city. As the surface stations are processed, any station within a distance

STASEP (in degrees of latitude) of a previously processed station will be discarded

unless the new one has less missing data than the previous one, in which case the

other previous station will be discarded.

IOBSWIN

integer

IGRIDFL

Flag which controls blending of gridded pressure level data and observations.

If

integer

IGRIDFL = 0, no pressure grid point data is used, only

observations.

If

IGRIDFL = 1, all observations (those not discarded as specified by the STASEP

and NOTSTA parameters - see above) and all pressure grid point data are used. If

IGRIDFL = 2, all observations (those not discarded) are used, but pressure data are

used only from geographic locations that (1) have no sounding closer than the

distance specified in GOBRAD and (2) do not have soundings in 3 or 4 quadrants

(defined by intersecting east-west and north-south lines) all closer than the distance

specified by GOBSEP (see GOBRAD and GOBSET). If IGRIDFL = 3, only

gridded pressure level data are used, no observations. If IGRIDFL = 4, the gridded

pressure data is taken as a first guess field. The observations are objectively

analyzed and applied to this first guess field as deviations.

GRIDWT

The implementation of the Barnes scheme in RAMS allows differential weighting of

integer array

any station or pressure data point to give it more or less influence compared to other

stations. GRIDWT has been implemented to reduce the weight of the gridded

pressure data set relative to the actual observations. For example, if a rawinsonde

observation were made at the same location as a gridded pressure point, a setting of

GRIDWT = .1, would give the rawinsonde 10 times more weight than the pressure

data. However, remember that the gridded data now are interpolated to the actual

RAMS grids, so that there are many more pressure grid points than soundings. Also,

there is a pressure grid point at the exact location of the grid to be analyzed.

Therefore, a much lower setting of GRIDWT will usually be optimal. The actual

value will take some experimentation but a value in the .1 to .001 may be

appropriate. Note also that the value is grid dependent and must have as many

values specified as NIGRIDS. In general, GRIDWT will become larger as the grid

spacing of the RAMS grid increases.

GOBSEP

If IGRIDFL (described above) is set to 2, a pressure data grid point will not be used

real

in the objective analysis if it is within GOBSEP degrees of an upper air observation.

GOBRAD

If IGRIDFL (described above) is set to 2, a pressure data grid point will not be used

real

in the objective analysis if there are observations in three quadrants of a circle of

GOBRAD radius (degrees). The circle is divided into quadrants by north-south and

east-west diameters.

WVLNTH

In the Barnes objective analysis scheme, a degree of smoothing to be applied is

real array

determined from two parameters. The first, WVLNTH, is the wavelength of the

data on the isentropic and σz surfaces (upper air) specified in kilometers to be

retained. The second, RESPON (see below) is the fractional amplitude at which to

retain that wavelength. Responses of other wavelengths are determined given a

value of .3 set for the "gamma' parameter in the Barnes scheme. Note that

WVLNTH is grid dependent and there must be as many values specified as

NIGRIDS.

SWVLNTH

Similar to WVLNTH (described above) but pertains to surface rather than upper air

real array

data and analysis. It uses the same RESPON value as WVLNTH. Note that

SVLNTH is grid dependent and there must be as many values specified as

NIGRIDS. For the surface objective analysis. Note that it is grid dependent and

there must be as many values specified as NIGRIDS.

RESPON

Percentage of specified wavelength amplitudes to be retained in both the upper air

real array

and surface analyses (see WVLNTH and SWVLNTH above). Note that RESPON

is grid dependent and there must be as many values specified as NIGRIDS.

$DIGITALFILTER Namelist

The $DIGITALFILTER namelist provides a means for …

Variable

Description

name

Flag that controls digital filter feature activation.

If applyDigitalFilter = . TRUE., turns on digital filter and if

applyDigitalFilter

applyDigitalFilter = . FALSE., turns it off.

boolean

Specifies the time, in seconds, that the model should run before applies

digitalFilterTimeWindow

the digital filter.

integer

$METEOGRAM Namelist

The $METEOGRAM namelist provides a means for …

Variable

Description

name

Flag that controls digital filter feature activation.

If applyDigitalFilter = . TRUE., turns on digital filter and if

applyMeteogram

applyDigitalFilter = . FALSE., turns it off.

boolean

Specifies the time, in seconds, that the model should write a meteogram

meteogramFrequency

result output.

integer

meteogramMap: filename of special file that contains polygons representing cities

or user defined areas.

string

meteogramDir: direcoty path to meteogramMap file.

string