Country maskout

[Douglas Clark]

Siraj,

You'll probably have to use the "set defval" command, see
http://grads.iges.org/grads/gadoc/gadocindex.html

In outline, I would suggest:
1. Create a field that is undef everywhere
e.g. define pmask=const(var,0,-a)
define pmask=maskout(pmask,pmask-1)
where var is any variable that you already have in your GrADS file.

2. Use set defval to reset values over Pakistan. You would have to work out the x,y coords of each point that you want to change, which could be tedious but probably isn't too bad because at GCM resolution Pakistan shouldn't cover many gridboxes.
e.g. 'set defval pmask 20 25 1' to change the value of pmask at x=20,y=25 to 1.
set defval will only work on t=1 (I think).

Doug

>>> sirajkhan78 at GMAIL.COM 07/03/2006 06:13:22 >>>
Hi All,

While working on GCM data, I have maskout surface from sea using maskout
function. Now I want to mask out my country (Pakistan) from global
data i.eexcept pakistan I want to assign undefined values to all grid
boxes.
How can I do it using gradsc or any subrotien??

--
Siraj Ul Islam
1: Research Fellow (Climate Section)
Global Change Impact Studies Centre
First Floor Saudi Pak tower
Blue Area Islamabad Pakistan
Ph :   92-51-9219785
Fax : 92-51-9219787

2: Mphil Scholar
Computational Physics and Simulation Group
Department of Physics
Quaid e Azam University
Islamabad.


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