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SQG

Attention!

sqg works with versions of DART before Manhattan (9.x.x) and has yet to be updated. If you are interested in using sqg with more recent versions of DART, contact DAReS staff to assess the feasibility of an update. Until that time, you should consider this documentation as out-of-date.

Overview

This is a uniform PV two-surface QG+1 spectral model contributed by Rahul Majahan.

The underlying model is described in: Hakim, Gregory J., 2000: Role of Nonmodal Growth and Nonlinearity in Cyclogenesis Initial-Value Problems. J. Atmos. Sci., 57, 2951-2967. doi: 10.1175/1520-0469(2000)057<2951:RONGAN>2.0.CO;2

Other modules used

types_mod
time_manager_mod
threed_sphere/location_mod
utilities_mod

Public interfaces

use model_mod, only : get_model_size
adv_1step
get_state_meta_data
model_interpolate
get_model_time_step
static_init_model
end_model
init_time
init_conditions
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

Optional namelist interface &model_nml may be read from file input.nml.

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.

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 element, indexed by index_in, in the model state vector. The location defines where the state variable is located.

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.

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;

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.

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.

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.

x Initial conditions for state vector.

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 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.

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 3D 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 3D 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 3D 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 NULL INTERFACE in this model.

ens_mean State vector containing the ensemble mean.

Namelist

We adhere to the F90 standard of starting a namelist with an ampersand '&' and terminating with a slash '/' for all our namelist input.

&model_nml
  output_state_vector = .false.
  channel_center = 45.0
  channel_width = 40.0
  assimilation_period_days = 0
  assimilation_period_seconds = 21600
  debug = .false.
/

This namelist is read in a file called input.nml

Contents Type Description
output_state_vector logical If .true. write state vector as a 1D array to the diagnostic output file. If .false. break state vector up into fields before writing to the outputfile.
channel_center real(r8) Channel center
channel_width real(r8) Channel width
assimilation_period_days integer Number of days for timestep
assimilation_period_seconds integer Number of seconds for timestep
debug logical Set to .true. for more output

Files

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

References

The underlying model is described in:
Hakim, Gregory J., 2000: Role of Nonmodal Growth and Nonlinearity in Cyclogenesis Initial-Value Problems. J. Atmos. Sci., 57, 2951-2967. doi: 10.1175/1520-0469(2000)057<2951:RONGAN>2.0.CO;2

Private components

N/A