PNNL

Abstract

This study applies the isentropic analysis to the vertical velocity of the atmospheric general circulation in an ensemble of coupled climate models. It is found that, in response to greenhouse gas increase under the Representative Concentration Pathway 8.5 scenario, at the end of the 21st century, the globally averaged isentropic streamfunction shows a robust shift toward smaller pressure and larger moist static energy (MSE), which can be understood using simple thermodynamic scaling. In addition, in global average, while the total upward mass transport decreases by about 7% in mid-to-lower troposphere, the total upward MSE transport increases by about 9%, both largely due to the eddies. While the weakening of the eddy mass transport primarily occurs in the tropics, the intensication of the eddy MSE transport is mostly over the midlatitudes, which implies an increase of the eective stratication in the entire globe, especially in the subtropics.