MODULE model_mod (9-variable)

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



DART interface module for the 9-variable model. The 16 public interfaces 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 model state variables. The distinctive part of the model interfaces is the namelist.

This model provides interesting transient off-attractor behavior that is something like gravity waves.





use model_mod, only : get_model_size

Optional namelist interface &model_nml may be read from file input.nml. The details of the namelist are always model-specific (there are no generic namelist values).

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. Required.

model_size The length of the model state vector.

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

Advances the model for a single time step. The time associated with the initial model state is also input although it is not used for the computation.

x State vector of length model_size.
time    Specifies time of the initial model state.

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 state vector element, indexed by index_in, in the model state vector. The location defines where the state variable is located. For 9-variable, the three X variables are at 0, 1/9, and 2/9, the three Y variables at 3/9, 4/9 and 5/9, and the three z variables at 6/9, 7/9, and 8/9 on a cyclic [0, 1] domain. The variable type is always returned as 1.

index_in    Index of state vector element about which information is requested.
location The location of state variable element.
var_type Returns the type (always 1) of the indexed state variable as an optional argument.

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

Given model state, returns the value interpolated to a given location in [0, 1] by linear interpolation. Variable locations are at i/9, i = 0, 1, ...,8, in the cyclic [0, 1] domain. So, a value of 1/18 is an average of the X1 and X2 variables. The type variable is not used here and istatus is always returned as 0 (successful interpolation).

x A model state vector.
location    Location to which to interpolate.
itype Not used.
obs_val The interpolated value from the model.
istatus Quality control information, always returned 0.

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

Returns the time step (forecast length) of the model; The time step defaults to 1 hour but is settable by namelist.

var    Smallest time step of model.

call static_init_model()

Used for runtime initialization of model; reads namelist, initializes model parameters, etc. This is the first call made to the model by any DART-compliant assimilation routine.

call end_model()

A stub since 9-variable requires no clean up.

call init_time(time)
type(time_type), intent(out) :: time

Returns the time at which the model will start if no input initial conditions are to be used. This is used to spin-up the model from rest. Sets time to 0 in this model.

time    Initial model time.

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

Returns default initial conditions for the model; generally used for spinning up initial model states. Values chosen here are 0.1 for all nine state variables.

x    Initial conditions for state vector.

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

This routine must write the model-specific attributes to a netCDF file. This includes coordinate variables and any metadata, but NOT the model state vector. We do have to allocate SPACE for the model state vector, but that variable gets filled as the model advances. models/template/model_mod.f90 contains code that can be used for any model as-is. The generic code prepares a file which will have the state vector written as a single 1-D array of data. This routine can be modified to save the data in form more closely related to the actual grid shape and variable type, and could also be extended to write additional attributes if desired. This routine is required for all models.

ncFileID    Integer file descriptor to previously-opened netCDF file.
ierr Returns a 0 for successful completion.

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 file descriptor to previously-opened netCDF file.
statevec A model state vector.
copyindex    Integer index of copy to be written.
timeindex The timestep counter for the given state.
ierr Returns 0 for normal completion.

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 particular model does not implement an interface for this and so returns .false. for interf_provided.

state State vector to be perturbed.
pert_state Perturbed state vector: NOT returned.
interf_provided    Returned false; interface is not implemented.

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

Pass-through to the 1-D 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 1-D 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 1-D 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 NULL INTERFACE in this model.

ens_mean    State vector containing the ensemble mean.



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.

   g                 = 8.0,
   deltat            = 0.0833333333333333,
   time_step_days    = 0,
   time_step_seconds = 3600  

Item Type Description
g real(r8) Model parameter, see comp_dt in code for equations.
delta_t real(r8) Non-dimensional timestep. This is mapped to the dimensional timestep specified by time_step_days and time_step_seconds.
time_step_days real(r8) Number of days for dimensional timestep, mapped to delta_t.
time_step_seconds real(r8) Number of seconds for dimensional timestep, mapped to delta_t.



filename purpose
input.nml to read the model_mod namelist the time-history of the model state before assimilation  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




Routine Message Comment
Various netCDF-f90 interface error messages From one of the netCDF calls in the named routine


none at this time



none at this time





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Contact: DART core group
Revision: $Revision: 6382 $
Source: $URL: $
Change Date: $Date: 2013-08-07 14:45:16 -0600 (Wed, 07 Aug 2013) $
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