regrid(field,field) != field

[senesis]

regrid(a,b) uses CDO operators griddes and e.g. remapbil for regridding field a on the grid of field b
When a == b, one should expect that the output is equal to a. This is not the case, as shown below (first plot is for a, second plot is for minus(regrid(a,a),a))
CDO is probably faulty here, but scriptregrid.shshould alleviate for that, and check if both field have the same grid before actually calling the CDO interpolator