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Both versions use 16 longwave bands which almost fit into the 13 "narrow" CKDMIP bands. The full spectral resolution uses 256 g-points, the reduced uses 128 g-points. Evaluation of present-day calculations against the line-by-line reference for the CKDMIP "Evaluation-1" dataset are as follows:
We Both are very good models, but we see that the reduced resolution degrades most metrics a little, except for 4-1100 hPa heating rates, which are unchanged. The warming bias in the mid-mesosphere introduced with the reduced spectral resolution is entirely associated with the 630-700 cm-1 band, where CO2 absorption is strongest.
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