PROGRAM `dart_to_cam`¶

Overview¶

dart_to_cam is the program that reads a DART restart or model advance file (e.g. perfect_ics, filter_ics, assim_model_state_id ... ). and overwrites the part of the CAM data in a single CAM restart file (usually caminput.nc) which is in the DART state vector. If you have multiple input files, you will need to rename the output files as you create them.

The list of variables extracted from the DART state vector and exported to the CAM netCDF file is controlled by the set of input.nml &model_nml:state_names_* variables.

If the input is a model advance file, containing 2 timestamps (the current model time and a future time the model should run until), this program also creates a separate file named times that contains three lines: the advance-to time, the current model time, and the number of hours to advance. These will need to be extracted and inserted in a CAM namelist to indicate to CAM how long to run.

This program also updates the date and datesec variables in the CAM netcdf file. Generally these are identical times since the assimilation doesn’t change the time of the data, but in case the original file had a different time that was overwritten in the state vector, it will update the time for consistency.

Conditions required for successful execution of dart_to_cam:

a valid input.nml namelist file for DART
a CAM ‘phis’ netCDF file [default: cam_phis.nc]
a DART restart file [default: dart_ics] (read)
a CAM restart file [default: caminput.nc] (read and written)

Since this program is called repeatedly for every ensemble member, we have found it convenient to link the DART input and CAM restart files to the default filenames dart_ics and caminput.nc). The output files may be moved or relinked as necessary.

Namelist¶

This namelist is read from the file input.nml. Namelists start with an ampersand ‘&’ and terminate with a slash ‘/’. Character strings that contain a ‘/’ must be enclosed in quotes to prevent them from prematurely terminating the namelist.

&dart_to_cam_nml
   dart_to_cam_input_file  = 'dart_ics',
   dart_to_cam_output_file = 'caminput.nc',
   advance_time_present    = .true.,
   /

Item	Type	Description
dart_to_cam_input_file	character(len=128)	The name of the DART restart file containing the CAM state.
dart_to_cam_output_file	character(len=128)	The name of the CAM restart netcdf file.
advance_time_present	logical	Set to .false. for DART initial condition and restart files. Use the .true. setting for the files written by filter during a model advance.

Modules used¶

assim_model_mod.f90
types_mod.f90
threed_sphere/location_mod.f90
model_mod.f90
null_mpi_utilities_mod.f90
obs_kind_mod.f90
random_seq_mod.f90
time_manager_mod.f90
utilities_mod.f90

Files read¶

DART namelist file; input.nml
DART initial conditions/restart file; e.g. dart_ics (read)
CAM restart file; caminput.nc (read and written)
CAM “phis” file specified in &model_nml::cam_phis (normally cam_phis.nc)

Files written¶

CAM restart file; caminput.nc (read and written)

References¶

none

PROGRAM dart_to_cam¶