Stereographic projection in GRADS

[Bernat Codina]

2007/11/12, Ernani de Lima Nascimento <elnascimento at ufpr.br>:

> I have a pre-projected field in a stereographic projection (at true
> latitude 45 degrees north, instead of the standard 60 degrees). My domain
> does **not** include the pole. Ok, GRADS has that pdef card that allows
> reading pre-projected data, but please correct me if I am wrong: I
> understand that one thing I will have to do first is to convert my field
> to the standard 60 degrees true latitude for this projection to work on
> GRADS, right?

You just have to provide the GrADS pdef tag with the grid spacing at
60 degrees, that you will have to compute. Tell me if you need the
formula.

> My other question is related to the ipole and jpole definition for pdef.
> Because the north pole is outside of my domain I will have to determine
> the (i,j) for the pole; because this (i_pole,j_pole) cannot be negative,
> then I understand that it has to be determined with respect to the
> lower-left corner of my domain. Is this what the pdef (ipole,jpole)
> expects me to provide?

Correct.

Bernat Codina
Dept. d'Astronomia i Meteorologia
Universitat de Barcelona