Rotated poles, HIRLAM GRIB and GrADS

[Wesley Ebisuzaki]

Tero,

     GrADS can do arbitrary grids.   You use the PDEF file or PDEF bilin
option.  All it needs is a binary file that specifies how to go from the
internal
grid to the external grid (rotated pole).   As for an example,
Grib2ctl.pl uses
the PDEF file option to support thinned lat-lon and gaussian grids.
(The binary
file is created on the fly.)

       http://grads.iges.org/grads/gadoc/pdef.html
       http://www.cpc.ncep.noaa.gov/products/wesley/grib2ctl.html

         Wesley Ebisuzaki


Tero Siili wrote:
> Dear GrADS users and developers,
>
> my colleagues and I are using a mesoscale model (based on the HIRLAM
> NWP model), which has the option of a rotated pole. This information
> is apparently stored in the GRIB-format output files.
>
> To put it simply: does GrADS know how to display - and if necessary,
> INTERNALLY convert the coordinates and wind vectors & interpolate to
> natural lat/lon coordinates - such data sets with arbitrary rotated
> pole(s)? The PDEF keyword available for .ctl files seems like a
> potential way to handle this, but is the PDEF versatile and flexible
> enough - or constrained to a fixed set of coordinate transformations?
> If PDEF can be used for this type of data transformation, could
> someone perhaps provide an example of how to define the PDEF field in
> the .ctl file? We are currently using GrADS version 1.9b4.
>
> A colleague of mine found a couple of external, standalone tools
> (xconv and convsh) which may help, but info on both GrADS'
> capabilities (or lack thereof) as well as on other useful conversion
> tools would be highly helpful.
>
> With best regards and looking forward to hearing more about this,
>
>
> Tero Siili
> SOHO Science Operations Coordinator
> European Space Agency, c/o NASA Goddard Space Flight Center, Mailcode
> 612.5
> Greenbelt MD 20771, United States of America
>
> Tel/EAF: +1 301 2869028
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