Poleward propagations of the ITCZ : Observations and theory

Abstract

Many features of the intra seasonal variation of the ITCZ over the Indian longitudes in the summer monsoon including poleward propagations emanating from oceanic regions and traversing both ocean and land to culminate in the seasonal trough have been simulated by a modified Version of the Webster model. The mechanism underlying the propagations in the model involves excess convective heating to the polewald side of the convergence zone relative to the equator ward zone and can operate on land or sea:  This differential arises in the model from the seasonal gradient of the  convective Instability and moisture availability and hence the Intensity factor of convective heating which is the product of the two factors. If the ratio of the convective heating to the vertical ascent In reality also depends on these two factors, the observed propagations could be generated by the same mechanism.