[gradsusr] how to obtain areal average in a given shapefile

[Muhammad Rahiz]

The issue with shapefiles is that the boundaries are often not in the form 
of a four sided polygon, which if they are facilitites the area averaging.

What I usually do is to average the biggest four sided polygon 
that I can find within the shapefile and then progressively work on 
smaller polygons. Dealing with boundaries is often the tedious part 
especially if you want to be as accurate as possible. After that, it's a 
matter of averaging everything out.

Another way is to mask the shapefile. I don't know how to do this in 
GrADS but there is a simple way of doing so in CDO.


-- 
Muhammad Rahiz
Researcher & DPhil Candidate (Climate Systems & Policy)
School of Geography & the Environment
University of Oxford

On Wed, 23 Feb 2011, Marcelino II Villafuerte wrote:

> Hi all,
> Aside from reading and writing a shapefile in grads
> (http://www.iges.org/grads/gadoc/gadocindex.html)
> is it also possible to produce an areal average [aave() function] of a
> specific parameter e.g. rainfall, 
> in a specific province or region prescribed in a shapefile?
> 
> 
> Thanks in advance!
> --
> ---------------------------------------
> Marcelino Q. Villafuerte II
> Weather Specialist I
> IAAS, CAD
> PAGASA-DOST
> 
> 
>