Why Are Surface Equatorial ENSO Winds Anomalously Westerly under Anomalous Large-Scale Convection?

Abstract

Previous work has shown that the near-surface tropospheric response to anomalous heating can be described in terms of damped equatorial Rossby waves and a damped equatorial Kelvin wave. The zonal and meridional extent of the dominant ENSO heating/cooling region is such that the westward decaying Rossby waves dominate the response. Consequently, eastward of the forcing region the flow is small. Zonal convergence caused by the heating and small zonal flow to the cast together imply that winds must be anomalously westerly in the beating region.