Improve convection/radiation interaction in the GFS physics suite to address a drift in SST for seasonal prediction

[lisa-bengtsson]

Description

The GFS physics suite at 100km yields too large cloud cover and optical depth, causing too much cloud shielding and a drift in Sea Surface Temperatures, SST for seasonal prediction. This is an issue for the Seasonal Forecast System baseline. The issue was identified to be related to too much convective cloud condensate passed in from the cumulus convection scheme.

Solution

A scale adaptive solution is proposed and tested for SFS and GFS resolutions, outputting updraft values of in-cloud condensate. We propose to add this change to SFS baselines as well as the HR4 prototype of the GFS.