Stratospheric Transport Changes Forced By Tropical Sea Surface Temperature Perturbation: Idealized Simulation

Abstract

The structure of mass transport in the stratosphere, as well as its dynamic behaviors, is explored by imposing idealized sea surface temperature (SST) perturbations in an aqua-planet model. Mass transport within stratosphere is simultaneously running through two processes: the diabatic circulation, also well known as the Brewer-Dobson Circulation (BDC), advecting air mass across isentropic surfaces, and the quasi-horizontal mixing ventilating air mass along isentropic surfaces. It is shown that, with an equatorial SST heating, the stratospheric transport will increase in strength, in a circumstance with both BDC and high-latitude isentropic mixing being accelerated. Behaviors of transport, for both BDC and isentropic mixing, turn out to be with more complexities when the imposed SST perturbation being relocated at different ranges of latitudes or expanding itself with larger longitudinal span. Dynamic diagnostics further relate the changes of stratospheric transport mainly to the changes of eddies, which are originated from the induction of SST perturbation.