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I am absolutely new to GIS.

I have imported a map with information in the counties of Germany. Additionally I have added a layer with information on SO2 concentration at various measuring stations in Germany:

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Additionally, I have already interpolated the SO2 data using IDW (based on the suggestions from the Federal Environmental Agency, who distributed the data):

enter image description here

I am now struggeling with calculating area means. That is, for my analysis I need one value of SO2 concentration for each county in Germany, which I can export to R.

I would very much appreciate your support!

Thanks

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2 Answers 2

What you are looking for is called Zonal statistics. Make sure to specify a field with unique values in your polygon file with counties.

I would probably also exclude any county that hasn't got any points in them at all, since the interpolation there will be very uncertain (or counties with no station within a certain distance).

NB: the suggested tool requires Spatial analyst extension.

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Thanks @Martin. I think that work. However, do you know how I can export it into a txt file or table? –  coolcats Apr 17 at 11:54
    
In ArcGIS 10.2 you can use Table to excel. –  Martin Apr 17 at 11:59
    
I tried that. However, I can only convert the the tables I have imported into ArcGIS from shape files. Do I have to do anything with my interpolated data before I can export it? –  coolcats Apr 17 at 12:08
    
Since that is a new problem and not directly related to this question, I think you should post that as a separate question where you can outline all details, like what you have tried and what happens when you do. I'll be happy to try and help in that new question instead. –  Martin Apr 17 at 12:10
    
great Thanks a lot! –  coolcats Apr 17 at 12:16

I would recommend using Zonal Statistics as Table rather than just Zonal Statistics -- since your end goal is a table (in Excel), it is a more direct workflow. The statistics are the same, but the output is a table.

I am not entirely sure whether Excel is able to open .dbf files (one of the available table formats) directly; if not, you can open it within ArcMap and export the table to a .txt file (comma-separated).

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Thanks @Erica, that works great! –  coolcats Apr 22 at 8:14

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