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DART standard interfaces for a two-layer isentropic primitive equation 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.
This model is a 2-layer, isentropic, primitive equation model on a sphere. TODO: add more detail here, including equations, etc.
types_mod time_manager_mod utilities_mod random_seq_mod threed_sphere/location_mod
|use model_mod, only :||get_model_size|
A note about documentation style. Optional arguments are enclosed in brackets [like this].
integer :: get_model_size
Returns the size of the model as an integer. For this model the default grid size is 96 (lon) by 48 (lat) by 2 levels, and 3 variables (U, V, Z) at each grid location, for a total size of 27,648. There are alternative include files which, if included at compile time instead of the default file, defines a grid at twice and 4 times this resolution. They have corresponding truncation values of T63 and T127 (the default grid uses T31).
|model_size||The length of the model state vector.|
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.|
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
For this model, the default grid is a global lat/lon grid, 96 (lon) by 48 (lat) by 2 levels. The variable types are U, V, and Z:
Grids at twice and 4 times the resolution can be compiled in instead by using one of the alternative header files (see resolt31.h (the default), resolt63.h, and resolt127.h).
|index_in||Index of state vector element about which information is requested.|
|location||The location of state variable element.|
|var_type||The type of the state variable element.|
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 a state vector, a location, and a model state variable type, interpolates the state variable field to that location and returns the value in obs_val. The istatus variable is always returned as 0 (OK).
|x||A model state vector.|
|location||Location to which to interpolate.|
|itype||Type of state field to be interpolated.|
|obs_val||The interpolated value from the model.|
|istatus||Integer value returning 0 for successful, other values can be defined for various failures.|
type(time_type) :: get_model_time_step
Returns the the time step of the model; the smallest increment in time that the model is capable of advancing the state in a given implementation. For this model the default value is 20 minutes (1200 seconds), but also comes with header files with times steps of 10 and 5 minutes (for higher grid resolution and truncation constants).
|var||Smallest time step of model.|
Used for runtime initialization of a model, for instance calculating
storage requirements, initializing model parameters, etc. This is the
first call made to a model by any DART compliant assimilation routines.
In this model, it allocates space for the grid, and initializes the grid locations, data values, and various parameters, including spherical harmonic weights.
A stub since the pe2lyr model does no cleanup.
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 model sets the time to 0.
|time||Initial model time.|
real(r8), dimension(:), intent(out) :: x
Returns default initial conditions for model; generally used for spinning up initial model states. This model sets the default state vector based on the initialized fields in the model. (TODO: which are what?)
|x||Initial conditions for state vector.|
integer :: nc_write_model_atts integer, intent(in) :: ncFileID
This routine writes the model-specific attributes to a netCDF file. This includes coordinate variables and any metadata, but NOT the model state vector. This model writes out the data as U, V, and Z arrays on a lat/lon/height grid, so the attributes are organized in the same way.
|ncFileID||Integer file descriptor to previously-opened netCDF file.|
|ierr||Returns a 0 for successful completion.|
integer :: nc_write_model_vars integer, intent(in) :: ncFileID real(r8), dimension(:), intent(in) :: statevec integer, intent(in) :: copyindex integer, intent(in) :: timeindex
This routine writes the model-specific state vector (data) to a netCDF file. This model writes out the data as U, V, and Z arrays on a lat/lon/height grid.
|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.|
real(r8), dimension(:), intent(in) :: state real(r8), dimension(:), intent(out) :: pert_state logical, intent(out) :: interf_provided
Given a model state vector, perturbs this vector. Used to generate initial conditions for spinning up ensembles. This model has no code to generate these values, so it returns interf_provided as .false. and the default algorithms in filter are then used by the calling code.
|state||State vector to be perturbed.|
|pert_state||Perturbed state vector|
|interf_provided||Returned false; interface is not implemented.|
type(get_close_type), intent(inout) :: gc real(r8), intent(in) :: maxdist
In distance computations any two locations closer than the given maxdist will be considered close by the get_close_obs() routine. Pass-through to the 3-D sphere locations module. See get_close_maxdist_init() for the documentation of this subroutine.
|gc||The get_close_type which stores precomputed information about the locations to speed up searching|
|maxdist||Anything closer than this will be considered close.|
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.
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(:)
Given a location and kind, compute the distances to all other locations
in the obs list. The return values are the number
of items which are within maxdist of the base, the index numbers in the
original obs list, and optionally the distances. The gc
contains precomputed information to speed the computations.
Pass-through to the 3-D sphere locations module. See get_close_obs() for the documentation of this subroutine.
real(r8), dimension(:), intent(in) :: ens_mean
Stub only. Not needed by this model.
|ens_mean||State vector containing the ensemble mean.|
This model currently has no values settable by namelist.
Zou, X., Barcilon, A., Navon, I.M., Whitaker, J., Cacuci, D.G.. 1993: An Adjoint Sensitivity Study of Blocking in a Two-Layer Isentropic Model. Monthly Weather Review: Vol. 121, No. 10, pp. 2833-2857.
none at this time
none at this time
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This open source software is provided by UCAR, "as is",
|Contact:||DART core group|
|Revision:||$Revision: 6382 $|
|Source:||$URL: https://svn-dares-dart.cgd.ucar.edu/DART/releases/Lanai/models/pe2lyr/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"|