Stereographic projection in GRADS

[Ernani de Lima Nascimento]

Thank you for the prompt reply and for clarifying those points! Now I will
be able to proceed.
Thanks.
Ernani Nascimento

> 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
>