Dipole index of the tropical Atlantic and precipitation regime in Cote de Voire

Abstract

J. Servain, a French scientist [21], proposed a dipole index of a thermal state of waters in the tropical Atlantic. In [8], the index is calculated as a difference between mean water surface temperatures in the northern and southern tropical Atlantic for each month of 1941-2000. The dipole index is assumed to characterize seasonal and interannual changes in the position of the intertropical convergence zone (ITCZ) and thermal equator and potentially is a predictor of the moistening regime in the West African countries. For Cote de Voire, based on the multiyear data on monthly precipitation, five equiprobable gradations were determined. The intercomparison of gradations of the dipole index of the tropical Atlantic and seasonal precipitation in Cote de Voire made it possible to reveal a number of interrelations that can be used for long-range forecasting of precipitation during a rain season.