Sensitivities of zonal mean atmospheric circulation to SST warming in an aqua-planet model

Abstract

Sensitivities of tropospheric winds and stratospheric Brewer-Dobson Circulation (BDC) to SST warming are explored in an aqua-planet atmospheric general circulation model. The tropospheric zonal wind change is quite sensitive to the location and sign of the gradient of SST perturbations with respect to the climatological jet. For the experiments with low latitude warming, the Hadley cell is intensified in the deep tropics, yet the Hadley cell boundary contracts for narrow meridional extents of warming and expands for broad extents of warming, associated with changes in extratropical eddy-driven winds. Despite the complex changes of tropospheric wave forcing, the strength of the BDC is increased for all the experiments with low latitude warming. For the experiments with high latitude warming, the strength of the BDC decreases only if the warming extending to the subtropics.