An Objective Method for the Identification of the Intertropical Convergence Zone

Abstract

A simple objective method for delineation of the ITCZ from daily 2.5 degree data on satellite measured outgoing longwave radiation and albedo is described. The method involves identification of grid points with a large fraction of deep convective clouds by imposition of a bispectral threshold and subsequent filtering to retain organized large-scale convection. The thresholds are derived so as to make the delineation by the objective method as close as possible to that from subjective scans by Sikka and Gadgil. The results of the objective method are similar to those obtained by McBride by subjective analysis of the winter monsoon region and Murakami's identification of convective regions based on pixel data.