Jump to DART Documentation Main Index |

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.

Contact: Jeffrey.S.Whitaker@noaa.gov

[top]

types_mod time_manager_mod utilities_mod random_seq_mod threed_sphere/location_mod

[top]

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) ::xtype(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_intype(location_type), intent(out) ::locationinteger, 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.

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:

- 1 = TYPE_u
- 2 = TYPE_v
- 901 = TYPE_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) ::xtype(location_type), intent(in) ::locationinteger, intent(in) ::itypereal(r8), intent(out) ::obs_valinteger, 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_attsinteger, 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_varsinteger, intent(in) ::ncFileIDreal(r8), dimension(:), intent(in) ::statevecinteger, intent(in) ::copyindexinteger, 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) ::statereal(r8), dimension(:), intent(out) ::pert_statelogical, 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) ::gcreal(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) ::gcinteger, intent(in) ::numtype(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) ::gctype(location_type), intent(in) ::base_obs_locinteger, intent(in) ::base_obs_kindtype(location_type), intent(in) ::obs(:)integer, intent(in) ::obs_kind(:)integer, intent(out) ::num_closeinteger, 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. |

[top]

This model currently has no values settable by namelist.

[top]

- The model source is in pe2lyr_mod.f90, and the spherical harmonic code is in spharmt_mod.f90. The various resolution settings are in resolt31.h, resolt63.h, and resolt127.h.

[top]

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.

[top]

N/A

none at this time

[top]

none at this time

[top]

N/A

[top]

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: | 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" |