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PROGRAM filter

Contact: Jeff Anderson
Reviewers:  
Revision: $Revision: 1.5 $
Release Name: $Name: pre_hawaii $
Change Date: $Date: 2004/12/22 20:48:13 $
Change history: see CVS log

OVERVIEW

Main program for driving ensemble filter assimilations. This program provides a number of options that are driven from its namelist. The number of assimilation steps to be done are controlled by the input observation sequence and by the time-stepping capabilities of the model being used in the assimilation. This documentation was created for the H-release of DART.




OTHER MODULES USED

types_mod
obs_sequence_mod
obs_def_mod
time_manager_mod
utilities_mod
assim_model_mod
random_seq_mod
assim_tools_mod
cov_cutoff_mod
reg_factor_mod
obs_model_mod
ensemble_manager



NAMELIST

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

namelist / filter_nml /  &
      async, adv_ens_command, ens_size, cutoff, cov_inflate, start_from_restart, &
      output_restart, obs_sequence_in_name, obs_sequence_out_name, &
      restart_in_file_name, restart_out_file_name, init_time_days, init_time_seconds, &
      output_state_ens_mean, output_state_ens_spread, num_output_ens_members, &
      output_interval,  num_groups, confidence_slope, outlier_threshold, &
      save_reg_series

Discussion

This namelist is read in a file called input.nml

Contents Type Description
async integer Controls whether models are advanced via a subroutine call or by writing initial condition files for ensemble members to disk and having shellscript advance the model. Option: 0 = advance by subroutine; 1 = shell advance using shell script piped to filter; 2 = advance by F90 calls to shell to advance model. Default value is 0.
ens_size integer Number of ensemble members to be integrated. Default is 20.
cutoff real(r8) Cutoff controls a distance dependent weight that modulates the impact of an observation on a state variable. The units depend both on the location module being used and on the covariance cutoff module options selected. Default is 0.2.
cov_inflate real(r8) Covariance inflation factor applied to prior estimate before each assimilation step. Default is 1.0 (no inflation).
start_from_restart logical Should initial ensemble states come from a restart file. Default is .false.
output_restart logical Should a restart file be written out for all ensemble members? Default is .false.
obs_sequence_file_name character(len=129) File name that contains and observation sequence file. Default is 'obs_seq.in'.
restart_in_file_name character(len=129) File name for a file containing restart state for all ensemble members. Default is 'filter_ics'.
restart_out_file_name character(len=129) File name for output restart file. Default is 'filter_restart'.
init_time_days integer Initial time of model (time is in days and seconds; see time_manager. If init_time_days and init_time_seconds are less than 0, the initial time comes from the time in the restart file. Default value is 0.
init_time_seconds integer Initial time of model in seconds. Default is 0.
output_state_ens_mean logical Output ensemble mean in state diagnostic files.
output_state_ens_spread logical Output ensemble spread in state diagnostic files.
output_obs_ens_mean logical Output ensemble mean in observation output file.
output_state_ens_spread logical Output ensemble spread in observation output file.
num_output_state_members integer This number of ensemble members is output to the state diagnostics file. If this is less than the total number of ensemble members the first subset is output. Default is 0.
num_output_obs_members integer This number of ensemble members is output to the observation output file. If this is less than the total number of ensemble members the first subset is output. Default is 0.
output_interval integer The frequency with which output state diagnostics are in assimilation times written. Default value is 1 meaning output is written at every observation time.
num_groups integer Number of groups for hierarchical group filter. Should be a divisor of the ensemble size. Default is 1.
confidence_slope real(r8) Controls strength of bias correction algorithm. See assim_tools module. Default is 0 (no correction).
outlier_threshold real(r8) Discard all observations where the prior ensemble mean and the observation value differ by more than this many of the expected standard deviations. A quality control flag value is incremented by 10000 if this check is violated for the prior estimate. Negative value means no quality control of this kind. Default value is -1.0
save_reg_series logical Save statistics about the regression series for different observation / state variable pairs. Currently only minimally supported for non-parallel low-order models. Default is .false.



FILES




REFERENCES


ERROR CODES and CONDITIONS

RoutineMessageComment
filter_generate_copy_meta_data output metadata in filter needs ensemble size < 10000 Ensemble sizes greater than require modifications to output ensemble code.



KNOWN BUGS




FUTURE PLANS

Further development to better support observations that can only be computed once is needed.

Discussion