masking

[Matthias Fripp]

It sounds like you will need to do something like this:

1. Create a file listing all the grid points in or near India (e.g.,
within a simple latitude and longitude range that covers all of India
and some surrounding areas).

2. Import this list into a GIS program and intersect it with India's
land area.

3. Export a list of Indian grid points from the GIS program.

4. Import this list into GRADS.

Step 1 would be easy to do, e.g., in a text (.csv) file created in
Excel, if your grid is regularly spaced.

Step 2 and 3 are easy if you have a GIS program and difficult
otherwise. I could help you with that if you want.

I don't know how you would do Step 4. I can easily create a text file
listing all the relevant points, but I don't know how you would
reference that text file from GRADS to create a mask variable. Anyone
else have ideas about this?

Matthias

On Tue, Oct 27, 2009 at 7:23 AM, Sachin Ghude <sachinghude at tropmet.res.in
 > wrote:
Hi,

I want to plot tropospheric NO2 only over the Indian grid points (not
Nepal, Pakistan
and BanglaDesh). Is there any such utility so that it will enable me
to plot data only
for  India girds in GRADs. ( my grid size is 0.25 x 0.25 degrees).

please do the needful..

bye..

Sachin

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://gradsusr.org/pipermail/gradsusr/attachments/20091027/175af873/attachment.html