The Role of Ekman flow and Planetary Waves in the Oceanic Cross-Equatorial Heat Transport

Abstract

A numerical model is used to mechanistically simulate the oceans? seasonal cross-equatorial heat transport, and the results of Oort and Vonder Haar (1976). The basic process of Ekman pumping and drift is found to be able to account for a large amount of the cross-equatorial flux. Increased easterly wind stress in the winter hemisphere causes Ekman surface drift poleward, while decreased easterly stress allows a reduction in the poleward drift in the summer hemisphere. When the annual mean flow is removed, a net flow at the surface from summer to winter hemispheres is noted. The addition of planetary and gravity waves to this model does not alter the net cross-equatorial flow, although the planetary waves are clearly seen. On comparison with Oort and Vonder Haar (1976), this adiabatic advective redistribution of heat is seen to be plausible up to 10?20°N, beyond which other dynamics and thermodynamics are indicated.