The Influence of Sea Surface Temperature Reemergence on Marine Stratiform Cloud

In the extratropics, sea surface temperature anomalies undergo a winter to winter reemergence process. During the summer, the ocean mixed layer rapidly shallows, wintertime temperature anomalies are stored underneath, and mixed back to the surface when the mixed layer deepens the following winter. Marine stratiform cloud occurrence is strongly influenced by SST, particularly in the subtropics and eastern boundaries of the world’s ocean basins. The global distribution of SST reemergence and SST controls on cloud amount are examined using satellite data. A region in the north-east Pacific Ocean is identified where wintertime sea surface temperatures are correlated with occurrence of marine stratiform cloud the following winter. We hypothesize that through this reemergence mechanism marine stratus cloud amount, and thus shortwave cloud radiative forcing, in the north-eastern Pacific exhibits memory on inter-seasonal and even multi-year time-scales, and may play a non-negligible role in intra-annual sea surface temperature variability.