4

I have a raster file on precipitation and I want to create zonal statistics as a table using a shapefile with boundaries of countries across the world. However it appears that I need to take into account that in different latitudes the corresponding area is different and thus I need to weight my statistic (mean etc.) for area.

Any suggestions on how I can do that?

3
  • 2
    I should clarify that I work with ARCGIS 10.1
    – An_Li
    Commented Mar 18, 2013 at 12:43
  • 1
    If I understand your problem correctly: use an equal-area projection. Then you do not have to "weight you statistic".
    – Jens
    Commented Mar 18, 2013 at 15:23
  • 2
    An_Li, @Jens offers the best solution: use an equal-area projection. However, if you wish to avoid reprojecting (and the resampling that necessarily goes along with that), your idea is quite workable. At the very end of gis.stackexchange.com/questions/53664/…, I describe how to obtain a weighted (zonal) average. For weights, use the cosine of the latitude.
    – whuber
    Commented Mar 18, 2013 at 18:04

1 Answer 1

1

If you are open for other GIS tools then have a look at SAGA-GIS:

http://sourceforge.net/projects/saga-gis/

There is a module called "Grid Statistics for Polygons" which does exactly what you are looking for.

1
  • Thanks for the comments. I will try the equal area projection. Unfortunately I am new to ARC GIS so I already have difficulties with already, let alone moving to a different software.
    – An_Li
    Commented Mar 18, 2013 at 15:51

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.