Effects of Model Resolution, Physics, and Coupling on Southern Hemisphere Storm Tracks in CESM1.3
Increasing the resolution from 1˚ to 0.25˚ in the atmosphere (same physics) coupled to the 1˚resolution ocean intensifies the strength of Southern Hemisphere storm tracks in closer agreement to observations. The 0.25˚resolution atmosphere with the older CESM1.1 physics coupled to the 0.1˚ocean has fewer low clouds, warmer Southern Ocean SSTs, a weaker meridional temperature gradient, and a degraded storm track simulation compared to the 0.25˚atmosphere with CESM1.3 physics coupled to the 1˚ocean.
Increasing model resolution does not always improve simulations of storm tracks because deficient physics in the atmospheric model can negate the gains attained by higher resolution in atmosphere and ocean.
Southern Hemisphere storm tracks intensify in closer agreement with observations with higher resolution in the atmosphere except in the model version with older physics, such that deficient physics in the atmospheric model, which produce less low clouds, a reduced meridional SST gradient, and weaker storms in the Southern Hemisphere, can negate the gains attained by higher resolution in atmosphere and ocean.