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Stock GIAF_JRA case with offsets of 0 for most datm fields and -5400 for SWDN


Ben Johnson
New Member
[I originally posted this thread in Non-component-specific topics > Infrastructure but moved it here to Non-component-specific topics > Data Models because this seems to be the correct topic.]


I’ve created a stock GIAF_JRA case using the cesm2_1_1 release on GLADE. When the user_datm.streams.txt* files get created, all of them have offsets of 0, except for SWDN.

> cd /glade/p/cesm/releases/cesm2_1_1/cime/scripts/
> ./create_newcase --case /glade/work/johnsonb/cases/GIAF_JRA.f09_g17.003 --compset GIAF_JRA --res f09_g17 --project P93300612 --run-unsupported

Moving to the case directory,

> cd /glade/work/johnsonb/cases/GIAF_JRA.f09_g17.003
> ./case.setup
> ./preview_namelists
> vim user_datm.streams.txt.CORE_IAF_JRA.GCGCS.PREC
> vim user_datm.streams.txt.CORE_IAF_JRA.GISS.LWDN
> vim user_datm.streams.txt.CORE_IAF_JRA.GISS.SWDN

and LWDN have offsets of 0 while SWDN has an offset of -5400.

Checking the headers of the netCDF files in the stream shows that PREC, LWDN, and SWDN have time values of 1.5 4.5 7.5 ... and time_bnds of [0,3] [3, 6] [6, 9] ...

The other fields Q_10, SLP_, T_10, U_10, V_10 all have offsets of 0 as well, although they do not have time_bnds and their time values are set to 0 3 6 ...

Is there a specific reason that SWDN has an offset and the other fields with time_bnds do not?

The SWDN offset is set in this file in the strm_offset entry:


I'm unable to find an explanation of the offset either in that file, in the JRA-55 specifications, or in the RDA handbook.

Thank you,
Ben Johnson / johnsonb