MODULE model_mod (COAMPS)

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$Id: model_mod.html 6382 2013-08-07 20:45:16Z nancy $

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Overview

DART interface module for the Coupled Ocean / Atmosphere Mesoscale Prediction (COAMPS ®) model. The 16 public interfaces listed here are standardized for all DART compliant models. These interfaces allow DART to advance the model, get the model state and metadata describing this state, find state variables that are close to a given location, and do spatial interpolation for a variety of variables required in observational operators.

The following model description is taken from the COAMPS overview web page:

"The Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS) has been developed by the Marine Meteorology Division (MMD) of the Naval Research Laboratory (NRL). The atmospheric components of COAMPS, described below, are used operationally by the U.S. Navy for short-term numerical weather prediction for various regions around the world.

The atmospheric portion of COAMPS represents a complete three-dimensional data assimilation system comprised of data quality control, analysis, initialization, and forecast model components. Features include a globally relocatable grid, user-defined grid resolutions and dimensions, nested grids, an option for idealized or real-time simulations, and code that allows for portability between mainframes and workstations. The nonhydrostatic atmospheric model includes predictive equations for the momentum, the non-dimensional pressure perturbation, the potential temperature, the turbulent kinetic energy, and the mixing ratios of water vapor, clouds, rain, ice, grauple, and snow, and contains advanced parameterizations for boundary layer processes, precipitation, and radiation.

The distributed version of the COAMPS code that can be downloaded from the web site has been designed to use the message-passing interface (MPI), OpenMP directives, and horizontal domain decomposition to achieve parallelism. The code is capable of executing efficiently across vector, parallel, or symmetric muti-processor (SMP) machines by simply changing run-time options."
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OTHER MODULES USED

types_mod
time_manager_mod
threed_sphere/location_mod
utilities_mod
obs_kind_mod
random_seq_mod
netcdf
typesizes
coamps_grid_mod
coamps_interp_mod
coamps_restart_mod
coamps_util_mod
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PUBLIC INTERFACES

use model_mod, only : get_model_size
 get_state_meta_data
 model_interpolate
 get_model_time_step
 static_init_model
 nc_write_model_atts
 nc_write_model_vars
 pert_model_state
 get_close_maxdist_init
 get_close_obs_init
 get_close_obs
 ens_mean_for_model
 adv_1step
 end_model
 init_time
 init_conditions

The last 4 interfaces are only required for low-order models where advancing the model can be done by a call to a subroutine. The COAMPS model only advances by executing the coamps program. Thus the last 4 interfaces only appear as stubs in this module.

A note about documentation style. Optional arguments are enclosed in brackets [like this].


model_size = get_model_size( )
integer :: get_model_size

Returns the length of the model state vector as an integer. This includes all nested domains.

model_size The length of the model state vector.


call get_state_meta_data (index_in, location, [, var_type] )
integer,             intent(in)  :: index_in
type(location_type), intent(out) :: location
integer, optional,   intent(out) ::  var_type 

Returns metadata about a given element, indexed by index_in, in the model state vector. The location defines where the state variable is located while the type of the variable (for instance temperature, or u wind component) is returned by var_type. The integer values used to indicate different variable types in var_type are themselves defined as public interfaces to model_mod if required.

index_in    Index of state vector element about which information is requested.
location Returns location of indexed state variable. The location should use a location_mod that is appropriate for the model domain. For realistic atmospheric models, for instance, a three-dimensional spherical location module that can represent height in a variety of ways is provided.
var_type Returns the type of the indexed state variable as an optional argument.


call model_interpolate(x, location, obs_kind, obs_val, istatus)
real(r8), dimension(:), intent(in)  :: x
type(location_type),    intent(in)  :: location
integer,                  intent(in)  ::  obs_kind 
real(r8),               intent(out) :: obs_val
integer,                intent(out) :: istatus

Given model state, returns the value of observation type interpolated to a given location by a method of the model's choosing. All observation kinds defined in obs_kind_mod are supported. In the case where the observational operator is not defined at the given location (e.g. the observation is below the model surface or outside the domain), obs_val is returned as -888888.0 and istatus = 1. Otherwise, istatus = 0. The interpolation is performed in the domain with the highest resolution containing the observation.

x A model state vector.
location Location to which to interpolate.
obs_kind Integer indexing which type of observation is to be interpolated.
obs_val The interpolated value from the model.
istatus Integer flag indicating the result of the interpolation.


var = get_model_time_step()
type(time_type) :: get_model_time_step

Returns the model base time step as a time_type. For now this is set to 1 minute.

var    Smallest time step of model.


call static_init_model()

Used for runtime initialization of the model. This is the first call made to the model by any DART compliant assimilation routine. It reads the model namelist parameters, initializes the pressure levels for the state vector, and generates the location data for each member of the state.



ierr = nc_write_model_atts(ncFileId)
integer             ::  nc_write_model_atts
integer, intent(in) ::  ncFileId 

Function to write model specific attributes to a netCDF file. At present, DART is using the NetCDF format to output diagnostic information. This is not a requirement, and models could choose to provide output in other formats. This function writes the metadata associated with the model to a NetCDF file opened to a file identified by ncFileID.

ncFileId    Integer file descriptor opened to NetCDF file.
ierr Returned error code.


ierr = nc_write_model_vars(ncFileID, statevec, copyindex, timeindex)
integer                            ::  nc_write_model_vars
integer,                intent(in) ::  ncFileID 
real(r8), dimension(:), intent(in) ::  statevec 
integer,                intent(in) ::  copyindex
integer,                intent(in) ::  timeindex 

Writes a copy of the state variables to a NetCDF file. Multiple copies of the state for a given time are supported, allowing, for instance, a single file to include multiple ensemble estimates of the state.

ncFileID    Integer file descriptor opened to NetCDF file.
statevec State vector.
copyindex Integer index to which copy is to be written.
timeindex Integer index of which time in the file is being written.
ierr Returned error code.


call pert_model_state(state, pert_state, interf_provided)
real(r8), dimension(:),   intent(in)    ::  state 
real(r8), dimension(:),   intent(out)   ::  pert_state 
logical,                  intent(out)   ::  interf_provided

Given a model state, produces a perturbed model state. This is used to generate initial ensemble conditions perturbed around some control trajectory state when one is preparing to spin-up ensembles. In the COAMPS interface, this can be done three different ways:

state State vector to be perturbed.
pert_state Perturbed state vector is returned.
interf_provided Returns .true. for this model.


call get_close_maxdist_init(gc, maxdist)
type(get_close_type), intent(inout) :: gc
real(r8),             intent(in)    :: maxdist

Pass-through to the 3-D sphere locations module. See get_close_maxdist_init() for the documentation of this subroutine.



call get_close_obs_init(gc, num, obs)
type(get_close_type), intent(inout) :: gc
integer,              intent(in)    :: num
type(location_type),  intent(in)    :: obs(num)

Pass-through to the 3-D sphere locations module. See get_close_obs_init() for the documentation of this subroutine.



call get_close_obs(gc, base_obs_loc, base_obs_kind, obs, obs_kind, num_close, close_ind [, dist])
type(get_close_type), intent(in)  :: gc
type(location_type),  intent(in)  :: base_obs_loc
integer,              intent(in)  :: base_obs_kind
type(location_type),  intent(in)  :: obs(:)
integer,              intent(in)  :: obs_kind(:)
integer,              intent(out) :: num_close
integer,              intent(out) :: close_ind(:)
real(r8), optional,   intent(out) :: dist(:)

Pass-through to the 3-D sphere locations module. See get_close_obs() for the documentation of this subroutine.



call ens_mean_for_model(ens_mean)
real(r8), dimension(:), intent(in)  :: ens_mean

A local copy is available here for use during other computations in the model_mod code.

ens_mean   Ensemble mean state vector


call adv_1step(x, time)
real(r8), dimension(:),   intent(inout) ::  x 
type(time_type),          intent(in)    ::  time 

This operation is not defined for the COAMPS model. This interface is only required if `synchronous' model state advance is supported (the model is called directly as a Fortran90 subroutine from the assimilation programs). This is generally not the preferred method for large models and a stub for this interface is provided for the COAMPS model.

x State vector of length model_size.
time Gives time of the initial model state. Needed for models that have real time state requirements, for instance the computation of radiational parameters. Note that DART provides a time_manager_mod module that is used to support time computations throughout the facility.


call end_model( )

Called when use of a model is completed to clean up storage, etc. A stub is provided for the COAMPS model.



call init_time(i_time)
type(time_type),        intent(in)  ::  i_time 

Returns the time at which the model will start if no input initial conditions are to be used. This is frequently used to spin-up models from rest, but is not meaningfully supported for the COAMPS model.



call init_conditions( x )
real(r8), dimension(:), intent(out) ::  x 

Returns default initial conditions for model; generally used for spinning up initial model states. For the COAMPS model just return 0's since initial state is always to be provided from input files.

x Model state vector.

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NAMELIST

This namelist is read from the file input.nml. Namelists start with an ampersand '&' and terminate with a slash '/'. Character strings that contain a '/' must be enclosed in quotes to prevent them from prematurely terminating the namelist.

&model_nml
  cdtg = '2006072500',
  y_bound_skip = 3,
  x_bound_skip = 3,
  need_mean = .false.,
/


Item Type Description
cdtg character(len=10) Date/time group.
x_bound_skip, y_bound_skip integer Number of x and y boundary points to skip when perturbing the model state.
need_mean logical Does the forward operator computation need the ensemble mean?


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FILES

filename purpose
input.nml to read the model_mod namelist
Prior_Diag.nc the time-history of the model state before assimilation
Posterior_Diag.nc  the time-history of the model state after assimilation
dart_log.out [default name] the run-time diagnostic output
dart_log.nml [default name] the record of all the namelists actually USED - contains the default values
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REFERENCES

The COAMPS registration web site is http://www.nrlmry.navy.mil/coamps-web/web/home and COAMPS is a registered trademark of the Naval Research Laboratory.

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ERROR CODES and CONDITIONS

RoutineMessageComment
nc_write_model_atts Time dimension ID # must match Unlimited Dimension ID # NetCDF file writing error

KNOWN BUGS

none at this time

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FUTURE PLANS

none at this time

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PRIVATE COMPONENTS

N/A

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Terms of Use

DART software - Copyright 2004 - 2013 UCAR.
This open source software is provided by UCAR, "as is",
without charge, subject to all terms of use at
http://www.image.ucar.edu/DAReS/DART/DART_download

Contact: Tim Whitcomb
Revision: $Revision: 6382 $
Source: $URL: https://svn-dares-dart.cgd.ucar.edu/DART/releases/Lanai/models/coamps/model_mod.html $
Change Date: $Date: 2013-08-07 14:45:16 -0600 (Wed, 07 Aug 2013) $
Change history:  try "svn log" or "svn diff"