rotated lat/lon grid

[Wesley Ebisuzaki]

Edit,

     Preliminary version for grib2ctl with better support of rotated
lat-lon grids.

         ftp://ftp.cpc.ncep.noaa.gov/wd51we/wgrib.scripts/grib2ctl.pl

The change is by Graziano Giuliani.  I had to modify the patch to use the
north rather than the south pole (?) and the current "PDEF" format.

This is a preliminary version because (1) I only have one sample file
and (2) there is no support for determining whether the winds
needs to be rotated.

     Wesley Ebisuzaki



Jennifer Adams wrote:
> A new PDEF entry for rotated lat/lon grids (ROTLL and ROTLLR) was
> implemented in version 2.0. Look in the pdef doc page
> http://iges.org/grads/gadoc/pdef.html.
> Jennifer
>
>
> On Apr 17, 2008, at 6:47 AM, Hágel Edit wrote:
>
>> Hi!
>>
>> I've started to use Grads just recently and I try to plot some grib
>> files. These files contain data on rotated lat/lon grid with the
>> following parameters:
>>
>> Data represent type:                                rotated lat/lon
>> Number of points along a parallel.                 306
>> Number of points along a meridian.                 260
>> Latitude of first grid point.                   -20.427
>> Longitude of first grid point.                  -46.475
>> Resolution and components flag.               10000000
>> Latitude of last grid point.                     31.373
>> Longitude of last grid point.                    14.524
>> i direction (East-West) increment.                 0.200
>> j direction (North-South) increment.               0.200
>> Latitude of southern pole of rotation.          -40.000
>> Longitude of southern pole of rotation.          22.000
>> Angle of rotation.                              .0000000000
>>
>> Could anyone help me how to plot these fields correctly, i.e. how to
>> tell grads about the rotation? I generated the ctl file with
>> grib2ctl.pl, and I get this as part of the ctl file:
>>
>> * Rotated LatLon grid: South pole lat -40.000000 lon 22.000000  rot
>> angle 0.000000
>> ydef 260 linear -20.427000 0.2
>> xdef 306 linear -46.475000 0.199996721311475
>>
>>
>>
>> Thanks in advance,
>> Edit Hagel
>
> --
> Jennifer M. Adams
> IGES/COLA
> 4041 Powder Mill Road, Suite 302
> Calverton, MD 20705
> jma at cola.iges.org <mailto:jma at cola.iges.org>
>
>
>