Air-Sea Interaction as a Propagator of Equatorial Ocean Surface Temperature Anomalies

Abstract

The westward propagation of equatorial sea surface temperature anomalies exceeds the surface drift velocity and is probably associated with propagating changes in the depth of the surface mixed layer and upper thermocline. These can be caused by equatorial Rossby waves and/or by air-sea interactions. In the present paper, it is shown that changes in the stress and heat flux associated with the passage of air over an ocean surface of variable temperature can produce a westward propagation of the temperature pattern regardless of Coriolis effects. The phenomenon is investigated in the framework of a two-layer channel model. A physical description of the mechanism is followed by the discussion of an approximate solution to the steady state and by a linear wave analysis which deals with the propagation and modification of an initially stipulated departure from the equilibrium.