The Weather Forecasting Forum

All,

A new test version of NGRB2PCG32 is availabke at the PCGRIDDS32 Home Page. This is a beta release to test two bug fixes.

#1. Fixes problems associated with calculation the Latitude grid correctly. If this is grid is incorrect, then the coriolis grid will be incorrect as well and will cause any diagnostic function in PCGRIDDS32 which uses the coriolis grid to be incorrect.

#2. Fixes problems with the PCG files created which have a letter incriment.

The executable file name is NGRB2PCG32-Beta.exe so it will not conflict with the version 1.2 file already in your system. this Beta file must be executed directly.

Please refer to the Release Notes for further details and please let me know if these problems are not fixed or other problems are found.

Thanks in advance,
Jeff Krob

Jeff,


I just tried the new version of NGRB2PCG32 and it would not process the grids.

Here is part of the NGRB2PCG32OUT file

NGRB2PCG32 VERSION BETA 11/08/2004

OUTPUT DATA DIRECTORY: c:\PCGRIDDS32\GRIDDATA\
FILE: fh.0001_tl.press_gr.sgrib20
---NEW GRIB DATA FILE OPENED
===== BEGIN READ ===== IGB100( 1 & 2) COPIED TO 1 & 2
GRIB EDITION 1
===== BEGIN NEW GRIB EDITION 1 RECORD =====
REC#,SIZE = 1 101682
NBYTES,IRDRC7,IRDREC= 101682 1016 1016
IRDST/IRDEND/IGRBZZ= 3 1015 3
UNABLE TO PROCESS IRREGULAR GRIDS
===== BEGIN READ ===== IGB100( 1016 & 1017) COPIED TO 1 & 2
READING NEW GRIB RECORD = 1018
GRIB EDITION 1
===== BEGIN NEW GRIB EDITION 1 RECORD =====
REC#,SIZE = 2 101682
NBYTES,IRDRC7,IRDREC= 101682 1017 2033
IRDST/IRDEND/IGRBZZ= 1019 2032 3
UNABLE TO PROCESS IRREGULAR GRIDS [list=]

Kevin

Kevin,

That is true. PCGRIDDS/PCGRIDDS32 never has been able to *accurately* handle irregular grids, they can only handle regular grids. Regulat grids are grids which have equal grid spacing N/S-E/W and with irregular grids, the N/S spacing is not the same as E/W. When PCGRIDDS goes to draw the background map, it uses longitude spacing (E/W) as the reference and it is assumed the N/S is the same. However, when you lay an irregular grid data over a regular grid background, the data will not line up with the geography; it will be streched or compressed. With this in mind (I stumbled over this while troubleshooting the accurate way the latitude grid is calculated), I have flagged within NGRB2PCG32 when an irregular grid is encountered and do not allow it to be processed. Irregular NCEP grids are not that common and it would take ALOT of work to make PCGRIDDS32 irregular grid compatible so, they are not supported.

Thanks,
Jeff

Jeff,

Thanks for your response. I appreciate your efforts.

Kevin