FAQ — Frequently Asked Questions

  • I have weird errors (MPI?) when I try to read a FA file…

    => the epygram.init_env() should be called at the beginning of your script(s), to be sure the arpifs4py library do not use MPI, or uses OpenMP with an initialized environment.

  • I have weird ecCodes errors…

    => check environment variables $[ECCODES|GRIB]_[SAMPLES|DEFINITION]_PATH and make sure they are consistent with your ecCodes install or unset them

  • There is a field in my Surfex FA file, recognized as H2DField by epygram whereas it is a meta-data field; how can I manage to read it ?

    => copy $EPYGRAM_INSTALL_DIR/src/epygram/data/sfxflddesc_mod.F90 into $HOME/.epygram/sfxflddesc_mod.F90, and add your field in there in the manner of another meta-data field of the same kind And warn the epygram team about it, so that it will enter next version default sfxflddesc_mod.F90.

  • I need to overwrite the faFieldName.def ecCodes definition file for FA fieldnames conversion to GRIB2 parameters:

    => copy $EPYGRAM_INSTALL_DIR/src/epygram/data/gribapi.def.??/ as $HOME/.epygram/gribapi.def.99/, then edit $HOME/.epygram/gribapi.def.99/grib2/localConcepts/lfpw/faFieldName.def and set any field therein.

  • My PC does not have enough memory to deal with these global spectral fields…

    >>> Legendre spectral transforms need XX.XX MB
>>> memory, while only YY.YY MB is available:
>>> SWAPPING prevented !

    => either:

    • run your script on supercomputers using the alias s1batch='sbatch -N 1 -p normal256 --mem 250000 -t 00:30:00' e.g.: s1batch myscript.py options -of -my --script

    • use the fa_sp2gp.py tool on supercomputers (using the above alias) to convert your file to all-gridpoint then work in gridpoint space

  • I have a brutal crash (e.g. SegFault) while working with some large size fields…

    => before running Python, you need to raise the stack size limit: ulimit -s unlimited

  • How to hide LFI/FA messages ?

    => either:

    • export FA4PY_MUTE=1

    • edit $HOME/.epygram/userconfig.py and set FA_mute_FA4py = True

  • How to modify values of parameters or options of ``epygram`` *configuration* ?

    => values of epygram.config can be modified in $HOME/.epygram/userconfig.py

  • How to modify the validity of a FA file ?

    => e.g. to set the cumulativeduration to 0: fa_resource.modify_validity(basis=fa_resource.validity.get(), cumulativeduration=datetime.timedelta(0))

(to be continued…)