NOAA-EMC / CMEPS

NUOPC Community Mediator for Earth Prediction Systems
https://escomp.github.io/CMEPS/
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remove ifrac_nstod from med_fraction_set #1

Closed DeniseWorthen closed 4 years ago

DeniseWorthen commented 4 years ago

The current implementation of med_fraction_set for nems is setting the ifrac using a two-step procedure where first the ifrac is mapped with nearest neighbor (ifrac_nstod) and then conservative (ifrac). A conditional is used to determine the final ifrac value.

This procedure results in the isolated coastal anomalies seen in the v0.6 milestone runs. See ufs-s2s-model issue 116 for complete details.

The use of ifrac_nstod is unnecessary; the ifrac can be mapped directly with mapnstod_consf.

The following is a section of tile3 from phyf000:07:30.tile3.nc, showing the locations of two of the coastal anomalies (stars). On the left is the sea ice concentration, on the right the land-sea-ice mask. Locations of suspicious coast points are marked with stars. v06

This is the same comparison when ifrac_nstod is removed and the ifrac is mapped directly with mapnstod_consf in med_fraction_set:

v06_ifrac_nstod