responsible person for code contribution to GrADS

[Eric Altshuler]

Dear Gudrun,

What kind of rotated lat-lon grid are you using? If it is the same as the one used in the NCEP Eta model, then grads has built-in support for it (the "eta.u" projection). The structure of the pdef statement is:

pdef isize jsize eta.u lonref latref dlon dlat

See the documentation at http://grads.iges.org/grads/gadoc/pdef.html.

In the Eta rotated lat-lon grid, the model grid's prime meridian (0 deg longitude) coincides with the meridian that passes through the domain center (lonref), while the model grid's equator (0 deg latitude) also passes through the domain center (latref). Thus, the model grid's (0 deg lon, 0 deg lat) point coincides with the domain center point (lonref, latref).

If your data is on a different type of rotated lat-lon grid, then you'll need to use the "bilin" option to pdef. This is more complicated and it's also explained in the pdef documentation.

Best regards,


Eric L. Altshuler
Assistant Research Scientist
Center for Ocean-Land-Atmosphere Studies
4041 Powder Mill Road, Suite 302
Calverton, MD 20705-3106
USA

E-mail: ela at cola.iges.org
Phone: (301) 902-1257
Fax: (301) 595-9793

----- Original Message -----
From: "Gudrun Nina Petersen" <g.n.petersen at UEA.AC.UK>
To: GRADSUSR at LIST.CINECA.IT
Sent: Friday, July 27, 2007 8:58:15 AM (GMT-0500) America/New_York
Subject: Re: responsible person for code contribution to GrADS

Hi Matthias,

I was just wondering if you had got any replies as I would be interested
in being able to use GrADS for data on rotated lat/lon grid.
Would have loved to have that code a few months ago. Instead of using
GrADS I'm using matlab for plotting my data.

Best regards,

G. Nina Petersen

Matthias Grzeschik wrote:
> Dear GrADS user list,
>
> I added some code to my copy of GrADS to support a rotated lat/lon grid
> via the pdef line in the ctl file.  I would like to give this changes
> back to the community.  Who is the correct person to ask, to have a look
> on the changes and maybe include this to the official version of GrADS?
>
> Thanks in advance and best regards,
> Matthias
>

--

Guðrún Nína Petersen
School of Environmental Sciences
University of East Anglia
Norwich
UK

email: g.n.petersen at uea.ac.uk
http://www.petersen.is/gudrun