CDO

Hi there, I am curious about the function sellonlatbox in a particular situation.

Take the HadCRUT gridded temperature data as an example (https://crudata.uea.ac.uk/cru/data/temperature/)

Some basic properties of the HadCRUT4 .nc file:
Spatial resolution: 5° x 5°, cartesian grid
Longitude: -177.5°E to 177.5°E
Latitude: -87.5°N to 87.5°N
Grid: regular 72x36

So, for a file such as this, my question is what exactly happens with the following command:

cdo sellonlatbox,-5,0,0,5 HadCRUT4_in.nc HadCRUT4_out.nc

I get a reasonable output - i.e. a single grid cell with sensible values.

However, I believe that the range I have specified (-5,0,0,5) actually spans 4 grid cells in the original file (-2.5 to -7.5 long and 2.5 to 7.5 lat). If so, is there some kind of interpolation / simple averaging between these cells in order to arrive at my new grid box?

Thanks for any clarifications. Feel like I am missing something obvious here!!
James