Contact: | Jeff Anderson |
Revision: | $Revision: 2801 $ |
Source: | $URL: http://subversion.ucar.edu/DAReS/DART/trunk/models/lorenz_04/model_mod.html $ |
Change Date: | $Date: 2007-04-04 22:11:48 -0600 (Wed, 04 Apr 2007) $ |
Change history: | try "svn log" or "svn diff" |
DART interface module for the Lorenz-05 models II and III. The 17 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 reference for these models is Lorenz, E.N., 2005: Designing
chaotic models. J. Atmos. Sci.,
62, 1574-1587.
Model II is a single-scale model, similar to Lorenz 96, but with
spatial continuity in the waves. Model III is a two-scale
model. It is fudamentally different from the Lorenz 96 two-scale
model because of the spatial continuity and the fact that both scales
are projected onto a single variable of integration. The scale
separation is achived by a spatial filter and is therefore not perfect
(i.e. there is leakage). The slow scale in model III is model II,
and thus model II is a deficient form of model III. The basic
equations are documented in Lorenz (2005) and also in the model_mod.f90
code. The user is free to choose model II or III with a Namelist
variable.
types_mod time_manager_mod oned/location_mod utilities_mod
Optional namelist interface &model_nml may be read from file input.nml.
Public routines in this model are:
integer :: var
Returns the length of the model state vector as an integer. Settable by namelist, the default is 960.
real(r8), dimension(:), intent(inout) :: x type(time_type), intent(in) :: time
Advances a model for a single time step using a four-step Runga-Kutta. The time argument is passed in but not used by this model.
x | State vector of length model_size. |
time | Gives time of the initial model state. Not used by this model. |
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 (at present, a variety of simple location models for support of gridpoint models are provided) while the type of the variable (for instance temperature, or u wind component) is returned by var_type. In this model there are no types so it always returns 1.
index_in | Index into the state vector. |
location | Returns location of indexed state variable |
var_type | If present always returns 1 |
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 of variable itype interpolated to a given location.
x | Model state vector. |
location | Location to which to interpolate. |
itype | Integer indexing which type of state variable is to be interpolated. Is ignored for this model since there is only a single type of variable. |
obs_val | The value of the observation from the model. |
istatus | Quality control information about the observation of the model state. 0 == successful. |
type(time_type) :: var
Returns the model time_step, which is settable by namelist.
var | The base time step of the model. The forecast length. |
A stub routine in this model.
Reads the namelist, allocates space for the state vector, initializes the locations, generates some initial parameters.
type(time_type), intent(in) :: time
Returns the time at which the model will start if no input initial conditions are to be used. This model sets initial time to 0.
time | The time at which the model will start if no input initial conditions are to be used. |
real(r8), dimension(:), intent(out) :: x
Sets the entire state variable to the value of the forcing and then slightly perturbs the first element.
x | Model state vector. |
integer, :: ierr integer, intent(in) :: ncFileId
Function to write model specific attributes to a netCDF file. 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. 0 == normal termination |
integer :: ierr 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 connected to NetCDF file. |
statevec | State vector. |
copyindex | Integer index to which copy in the file is to be written. |
timeindex | Integer index of which time in the file is being written. |
ierr | Returned error code. 0 == normal termination. |
integer :: ierr integer, intent(in) :: ncFileID real(r8), dimension(:), intent(out) :: statevec integer, intent(in) :: copyindex integer, intent(in) :: timeindex
A general interface routine to read the state vector at a particular time for a particular ensemble member.
ierr | Returned error code. 0 == normal termination. |
ncFileID | Integer file descriptor connected to NetCDF file. |
statevec | State vector. |
copyindex | Integer index to designate copy to be read. |
timeindex | Integer index of desired time to be read. |
This interface is essentially untested in the Lorenz 04/05 model. It began life as a stub, but there is so little to it ... TJH 05 Aug 2005.
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. A DART compliant model can choose not to provide an implementation of this algorithm and use the default mechanism in DART by simply returning .false. as a returned value for the interf_provided argument. In this case, DART perturbs the state to generate ensemble members by adding a random sample from a N(0.0, 0.002) distribution independently to each state variable. This model returns .false. for interf_provided and uses the default DART perturbation routine.
state | State vector to be perturbed |
pert_state | Perturbed state vector is returned |
interf_provided | Returns false to have DART perturb state |
The Lorenz 04/05 model relies implicitly on the default DART perturbation mechanism, i.e. this routine always returns .false..
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.
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.
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.
real(r8), dimension(:), intent(in) :: ens_mean
A NULL INTERFACE in this model.
ens_mean | Ensemble mean state vector |
We adhere to the F90 standard of starting A NAMElist with an ampersand '&' and terminating with a slash '/'. If the namelist extends over more than one F90 line, the F90 continuation character must be used, this is also an ampersand (just to confuse things).
namelist / model_nml / & model_size, forcing, delta_t, space_time_scale, & coupling, K, smooth_steps, & time_step_days, time_step_seconds, model_number
This namelist is read in a file called input.nml
Contents | Type | Description |
---|---|---|
model_size | integer | Number of variables in model, default is 960. |
forcing | real(r8) | Forcing, F, for model, default 15.0 |
delta_t | real(r8) | Non-dimensional timestep, default 0.001 |
space_time_scale | real(r8) | Determines temporal and spatial relationship between fast and slow variables (model III), default 10.0 |
coupling | real(r8) | Linear coupling between fast and slow variables (model III), default 3.0 |
K | integer | Determines the wavenumber of the slow variables (K=1, smooth_steps=0 reduces model II to Lorenz 96), default 32 |
smooth_steps | integer | Determines filter length to separate fast and slow scales, default 12 |
time_step_days | integer | Arbitrary real time step days, default 0 |
time_step_seconds | integer | Arbitrary real time step seconds (could choose this for proper scaling), default 3600 |
model_number | integer | 2 = single-scale, 3 = 2-scale. (This follows the notation in the paper.) default 3 |
The reference for these models is Lorenz, E.N., 2005: Designing
chaotic models. J. Atmos. Sci.,
62, 1574-1587.
Routine | Message | Comment |
---|---|---|
nc_write_model_atts nc_write_model_vars |
Various NetCDF-f90 interface error messages | From one of the NetCDF calls in the named routine |