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20010321: rebuilding gempak for large gribs

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  • Subject: 20010321: rebuilding gempak for large gribs
  • Date: Wed, 21 Mar 2001 16:21:34 -0700
>From: "Arthur A. Person" <address@hidden>
>Organization: UCAR/Unidata
>Keywords: 200103211815.f2LIFnL03774

>Hi,
>
>I want to decode 4km precip grib data from NCEP using dcgrib2 but need to
>make mods to allow for larger gribs and grids (1160 X 880).  The NCEP
>instructions said to use nagrib but I should be able to use dcgrib2,
>correct?  I've identified that I need to make MAXGRIBSIZE larger in
>decode_grib.c and I think I need to make LLMXGD larger for the overall
>grid size.  Can you tell me if LLMXGD is the only other thing I need to
>modify to make this work correctly?  Do I then need to rebuild the whole
>gempak package, or can I just build part of it to get dcgrib2 to work?
>
>                                     Thanks.
>
>                                       Art.
>
>Arthur A. Person
>Research Assistant, System Administrator
>Penn State Department of Meteorology
>email:  address@hidden, phone:  814-863-1563
>


Art,

You need to rebuild the entire package (including all the $GEMLIB library
files) whenever changing any array sizes defined in the $GEMPAK/include
files (since this will change common block sizes and sizes passed in
subroutine calls). You can run "make distclean" from $NAWIPS to
remove the $GEMLIB files as well as any other build files from the tree.

LLMXGD should be changed in both the fortran GEMPRM.xxx file as well as 
the C gemprm.h file. The computation heap for grids defined as LLMDGG
is related since this is the amount of space used by computations 
(eg each grid in the computation uses this space) that
use more than 1 grid- so it should be large enough to allow you to
hold at least 4x the grid size probably.

The MAXGRIBSIZE parameter in decode_grib.c is the size of the buffer
for the largest "grib message" you will encounter in the data stream
(that is the grib packed message). 


Steve Chiswell