rotated lat/lon grid

[martynas kazlauskas]

Hi,

I use grads for ploting model data with a rotated
lat-lon grid.

The approach is relatively simple, but may not be
satisfying for everyone - rotate the map set (hires,
lowres or whatever else), construct a "normal" ctl
file and then overlay the map set so that you "see"
the right locations etc.

However, this has to be tested on the file, because,
i'm not sure how that looks like (we use rotation of
-30 0), and the results are ok for us.

I have rotated one map set with your coordinates, and
i can e-mail it to you if you like (i hope it works,
because i have no files to test it with)

Martynas Kazlauskas


--- Hágel Edit <hagel.e at MET.HU> 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
>



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