Satellite Radiance DA prepare initial satbias files and others

If one wants to do satellite radiance DA, one must prepare the initial satbias files correctly based on the experiment setup.

The initial satbias files may be copied from previous RRFS.v2 runs (retrospective, realtime, or operational runs).
If none of the above is available, rrfs-workflow will use the staged satbias files under ${FIXrrfs}/satbias_init.

To prepare the initial satbias files, one will need to run the following commands before running the ROCOTO workflow.

cd ${expdir}
source qrocoto/load_qrocoto.sh
prep_satbias.sh  YYYYMMDDHH  [satbias_path]

1. How to determine the above YYYYMMDDHH parameter for retros?

(1). Generally, YYYYMMDDHH is the cycle before the first JEDIVAR/GETKF_SOLVER cycle of a retro.

The first JEDIVAR/GETKF_SOLVER cycle may be different depending on whether we have spinup cycles.

Example:
a. A retro starts at 2024050600 without spinup cycles, then the first JEDIVAR/GETKF_SOLVER cycle is 2024050600, and we will use 2024050523 when running prep_satbias.sh.
b. A retro starts at 2024050600 with spinup cycles starting at 03/15z, then the first JEDIVAR/GETKF_SOLVER cycle will be 2024050603 and we will use 2024050602 when running prep_satbias.sh.

(2). What about COLDSTART_CYCS_DO_DA=false?

Although we don't do DA at the cold start cycles, the JEDIVAR/GETKF_SOLVER cycle will run regardless and it will roll over stabias files for the next cycle.

(3). What about real-time runs?

Real-time runs can look back 5 cycles to find satbias files. So, real-time POCs only need to make sure there are satbias files available in the past 5 cycles.
In the situation when we bump the version number of rrfs-workflow or rrfs-workflow stops for more than 5 hours, real-time POCs can utilize the prep_satbias.sh tool as well.

2. How to determine the above [satbias_path] parameter for retros?

This parameter is optional. If it is missing, prep_satbias.sh will copy staged satbias files from ${FIXrrfs}/satbias_init.
One can put satbias files in any location as long as it is accessible by the prep_satbias.sh command.