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esmf-org / esmf

The Earth System Modeling Framework (ESMF) is a suite of software tools for developing high-performance, multi-component Earth science modeling applications.
https://earthsystemmodeling.org/
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Change normalization value for bilinear interpolation maps? #170

Closed czender closed 10 months ago

czender commented 1 year ago

ESMF_RegridWeightGen adds the global attribute normalization = "destarea" ; to map-files produced by the bilinear interpolation algorithm. This is confusing, since my understanding is that destarea only means something useful for conservative interpolation methods. In that case destarea means normalize by the destination area fraction (frac_b). For bilinear interpolation, the destarea algorithm is a no-op because area fractions are not involved in the calculation. This is mathematically equivalent to frac_b=1, though in reality bilinear interpolation does no normalization. Hence the normalization = "destarea" ; can confuse people. If you agree with this reasoning, please consider changing the normalization = "none" ; or something similar. Feedback or clarifications welcome. Also pinging @rljacob and @iulian787 who have encountered this issue.

billsacks commented 11 months ago

@czender - thanks a lot for reporting this. The ESMF core team discussed it this morning and agree that this should be changed. @oehmke 's suggestion was to use normalization = "N/A" for anything other than conservative maps; I plan to make the change to do that.

czender commented 11 months ago

Looking forward to it, thanks!