ON THE MERIDIONAL CIRCULATION AND RELEASE OF KINETIC ENERGY IN THE TROPICS

Abstract

The mean meridional circulation is computed for the northern hemisphere winter. The equatorward current in the low troposphere has a strength of l?3 mps near 10 to 15 deg lat, and the return current, centered near 200 mb, has about the same speed. An inactive layer without much net poleward or equatorward component extends from 700 to 400 mb. Next, the release of kinetic energy by the meridional circulation is calculated, and it is shown that this release equals the kinetic energy export from the tropics to the middle latitudes. Finally, the mean meridional circulation exports heat from the tropics poleward; at 15 deg lat this heat transport has the right order of magnitude to balance the net heat loss in higher latitudes.