Equatorial Energy Accumulation and Emanation Regions: Impacts of a Zonally Varying Basic State

Abstract

Abstract Previous studies have suggested that the regions of mean anomalous perturbation kinetic energy which exist in the vicinity of the equatorial upper-tropospheric westerlies are the result of the propagation of extratropical synoptic and low frequency waves through the equatorial “westerly duet” where a subsequent wave energy convergence occurs. The proposition that these perturbed equatorial regions may arise from remote equatorial energy sources is investigated. It is shown that three criteria must be met. The first two, the existence of wave energy sources along the equator and a mechanism to transport that energy longitudinally, are accounted for relatively easily with existing theory of divergent, trapped equatorial modes. The third criterion, the requirement of a mechanism for an accumulation of transient energy in the equatorial stretch flow (i.e., nonzero ūx), is not immediately obvious and requires exploration to develop new concepts. Using simple WKBJ arguments it is shown that within a re...