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G. Updating Climatological Background Error Statistics

rtodling edited this page Jun 22, 2021 · 4 revisions

Overriding default Background Error Covariance

It is something desirable to override the defaults background error covariance. Examples of cases in which that is necessary are (i) when trying to re-tune background errors due to systems changes; or (ii) testing with a new resolution (horizontal or vertical). The location of the background error files is defined by the environment variable BERROR. The ideal location to reset this variable is in the env configuration file FVDAS_Run_Config residing in FVHOME.

A typical resetting would be something like:

setenv BERROR $FVHOME/run/Berror

where the subdirectory Berror would be created by the user under the FVHOME/run directory and a desirable file with the background error statistics for the resolution of interest would be place under it. The user should be aware of naming conventions. Any background error file placed under this subdirectory of run would have to follow the template name:

lZLEVxNLONyNLAT.berror_stats_psoz_gcv.bin

where ZLEV is the number of levels, e.g., 72, 91, 181 and (NLON,NLAT) are the typical GEOS regular horizontal grid resolutions, e.g. (72,46), (576,361), etc.