The Influence of a resolved Gulf Stream on the decadal variability of southeast US rainfall
Ocean variability is a dominant source of remote rainfall predictability, but in many cases the physical mechanisms driving this predictability are not fully understood. This study examines how ocean mesoscales (i.e., the Gulf Stream SST front) affect decadal southeast US (SEUS) rainfall, arguing that the local imprint of large-scale teleconnections is sensitive to resolved mesoscale features. Based on global coupled model experiments with eddying and eddy-parameterizing ocean, we find that a resolved Gulf Stream improves localized rainfall and remote circulation response in the SEUS. The resolved Gulf Stream influences the boundary layer, driving a barotropic circulation response, thus affecting decadal SEUS rainfall due to a westward extension of the North Atlantic Subtropical High. The eddy-parameterizing simulation fails to capture the sharp SST gradient associated with the Gulf Stream and overestimates the role of tropical SST in the SEUS rainfall due to its classical wintertime connection with the El Niño/Southern Oscillation.
Geophysical Research Letters