search

NOAA-EMC / WW3

WAVEWATCH III
Other
260 stars 525 forks source link

grib2 warning issue for jpeg packing (default in ww3 with NCEP2) #923

Open aliabdolali opened 1 year ago

aliabdolali commented 1 year ago

Describe the bug The following warning would show up once wgrib2 is executed on the outputs of ww3_grib if wave partitions are in the fields and for the cases some partitions are empty: Warning: g2lib/g2clib jpeg encode/deocde may differ from WMO standard, use -g2clib 0 for WMO standard

Some info from wgrib2 developers:

   Wgrib2 (wgrib2.c) flags "simple", "complex", "jpeg" and"png" packing if
   1. constant field
   2. decimal scale factor not equal to  0
   3. reference value not equal to  0.0
The UPP probably uses a decimal scale factor = 0 to avoid the g2lib bug.

To Reproduce Add partitioning to ww3_grib.inp and then try to read or convert the generated grib2 files by WW3.

Expected behavior No warning should show up.

One suggestion is to change IDRSNUM to 2 (complex packing). or, in operational applications like GLWUv2, @sbanihash, she applied the following operator on grib2 files. wgrib2 $in_file -set_grib_type complex2 -grib_out $out_file where $in_file is the grib2 file generated by ww3 and $out_file would be the new one with complex packing.

This should be addressed for GEFS, GFS and future applications with WW3 and grib2 outputs.

sbanihash commented 1 year ago

I have tried changing the IDRSNUM to 2 in the ww3_grib.F90 and the warning did not go away. Maybe more settings should be modified in the code.