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Parallel grib2 in NCEP POST

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Monday, 24 January 2011
Parallel grib2 in NCEP POST
Jun Wang, NOAA/NWS/NCEP, Camp Springs, MD

In NCEP, a unified POST processor NCEP POST is maintained to generate POST products. Changes are made in the current NCEP POST repository to build in grib2 output capability. To accommodate the increased information required by grib2 output, the text format POST control file is upgraded to XML format post control file, a FORTRAN program is generated to read in the XML post control file. A module is developed to utilize the NCO grib2 templates and to parallel generate the grib2 message for each post field; MPI I/O is applied in writing grib2 messages to speed up the whole write processing time. Tests are done for GFS master file (1152*576, 664 fields) for NEMS GFS model and NAM grid 218 file (614*218, 1098fields) for NEMS NMMB model. The results show that compared to output GRIB1 data, the total time to output JPEG packing GRIB2 data by running the POST processor saves about 17% and disk space saves about 65%.

The modified code is backward compatible; it still keeps the capability of reading in text format POST control file and generating grib1 file.