masking

[Rupak Rajbhandari]

Hi,

Creating a masking file is not a simple procedure. Here I am sending you a
masking instruction I prepared (last year  for small training group in
Nepal). The masking file is for 0.1 resolution, so you need to edit a
little. The attached RAR file consists of a instruction file and two fortran
programs. In addition you will need ArcView GIS and India shape file
(boundary polygon) and fortran compiler. You should first edit the program
to suit your resolution. The rest should be clear from the instruction file.

Once the masking file has been created, simply replace the master file with
undefined values where grid point point values are zero in the masking file.

Hope it helps!

-rupak





On Tue, Oct 27, 2009 at 9:04 PM, Matthias Fripp <matthias.fripp at eci.ox.ac.uk
> wrote:

> 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
>>
>
>
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