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20020115: Maximum File Grid size in Gempak

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  • Subject: 20020115: Maximum File Grid size in Gempak
  • Date: Tue, 22 Jan 2002 10:49:47 -0700
>From: "Siffert, Andy" <address@hidden>
>Organization: UCAR/Unidata
>Keywords: 200201151416.g0FEGSx02929

>
>This question might be two vague, but what is the maximum file grid size
>gempak can handle. 
>and  is there anyway to read an IEEE file into GEMPAK without converting it
>into .grb first.
>If not:
>Is it even possible to go from IEEE to .grb to GEMPAK?
>
>Thanks,
>Andy
>


Andy,

The maximum grid file size is defined in the $GEMPAK/include/MCHPRM.xxxx
and gemprm.h files with the LLMXGD parameter. Currently, in my distribution 
I have this set to 400,000 points.

If you change this, you should also make sure that the LLMDGG
parameter in GEMPRM.PRM is at least 3 times LLMXGD (and hopefully larger)
since that is the menory needed to compute a grid quantity. If you are
computing something that needs several grids to be used, then you
have to have enough space to oad each grid and store the output.

IEEE is generally a floating point number storage format, rather than grid 
standard. GEMPAK would not know anything about that. You would have to
create a decoder, like dcgrib2, that would read your input file and create
GEMPAK grids.

Steve Chiswell