Re: a very large grib file

> I have a grib file of 7 Gb. Can NCL split this file into smaller pieces, either
> by retaining the format or by converting it to NetCDF? Current NCL functions
> seem not to be supporting files larger than 2 Gb. If NCL cannot handle files
> like this at all, could you suggest a way for doing this task?
> _______________________________________________

[1] smaller grib files

    NCL does not write GRIB so the answer is "no".

[2] It could be converted to netCDF. However, the file
    size would be larger. NCL supports netCDF files
    greater than 2GB but no single variable can be > 2GB

    GRIB's strength is that it is efficient at storing data.
    Convert GRIB to float and storing as netCDF usually
    results in a netCDF files that is 2-3 time larger
    than the original GRIB file.

[3] suggestion ... use "wgrib" to partition the grib file
    into smaller files.

    http://www.cpc.ncep.noaa.gov/products/wesley/wgrib.html

    see the "tricks" section

    ftp://ftp.cpc.ncep.noaa.gov/wd51we/wgrib/tricks.wgrib
        
[4] comment: GRIB is a record format not a file format.
    In fact, it only recognizes 2-dimensional horizontal grids.
    NCL scans the grib records and creates the multidimensional
    records that look like netCDF variable/files.
    

Perhaps an NCL developer can add more?

Regards,
D
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Received on Fri Mar 09 2007 - 07:41:17 MST