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Grid Issues
http://www.weathergraphics.com/forum/viewtopic.php?f=7&t=1091
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Author:  ncwxman [ Thu Nov 02, 2006 12:30 pm ]
Post subject:  Grid Issues

HELP!

I'm not sure what to think about this but, it does seem to be an issue to me.

Jeff, I think the problem I was having with grib2 files were related to the ftp program I use because I was able to get them to covert correctly this morning in NGRB2PCG32 without any problems when I used the grib download part of WINGRIDDS. However, I have run into a problem with the Grid #003, 1x1 degree lat/lon grid.

Data does not display correctly.

Image

Should look like the Grid #004, 0.5x0.5 degree lat/lon grid

Image

So, I ran the ALAT and ALON commands for the 003 grid. Everthing looked fine with the lats but the lons

Image

So, next I thought I'd run the ALAT and ALON commands for the 004 grid to see if they were ok. Again, lats are fime but, the lons are not.

Image

Should not the lons in the griddata file line up with that drawnn on the map? My biggest issue with all this is that the data in the 003 grib files is not displaying like the 004 grib files. But, I'm also concerned about the lons not displaying correctly.

Data source: ftpprd.ncep.noaa.gov/pub/data/nccf/com/gfs/prod/gfs.t00z.pgrbf03.grib2
for the Grid #003, 1x1 degree lat/lon grid.

The Grid #004, 0.5x0.5 degree lat/lon grid is already in the grib download menu.

Thank you,

Kevin

Author:  jkrob [ Thu Nov 02, 2006 6:22 pm ]
Post subject: 

Hey Kevin,

I would bet dollars to doughnuts this is the same issue as what you were seeing with the NOGAPS data...the N-hemi/S-hemi data is swapped. Go grab the same FHour for GFS Grid 003, 004 & the NOGAPS GRIB file. Ingest them then display a common parameter (HGHT 500) at the full grid resolution (AREA 0 0 0) & compair the data. I'll bet GFS grid 003 & NOGAPS look the same (wrong) but GFS looks different (correct).

The grid 003 *used* to process properly because I had to adjust NGRB2PCG32 to accomidate a data N/S inversion. Now, it look that since they went to GRIB2, they *fixed* the inversion in the NCEP data & now, NGRB2PCG32 puts it back wrong (sigh...).

There are actually flags in the GRIB data (GDS Octet 11-Scanning Mode) & I need to get NGRB2PCG32 to track that Scanning Mode flag & convert those Lat/Lon grids which scan from South-to-North but ignore those which scan from North-to-South. Ain't GRIB fun??? :-/

Thanks,
Jeff

Author:  ncwxman [ Tue Nov 07, 2006 11:20 am ]
Post subject:  Still an issue

Jeff,

I have downloaded and installed the latest update and the NOGAPS & the GFS003 grids still don't look correct.

Regards,

Kevin

Author:  jkrob [ Tue Nov 07, 2006 12:34 pm ]
Post subject: 

Kevin,

I presume, when you say "...still don't look correct", you mean still has the same problem or is this problem different but still not right?

Please send me the first few lines of your NGRB2PCG32.OUT file.

Thanks,
Jeff

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