Three dimensional flow,temperature and humidity patterns and atmospheric fluxes over Africa during northern summer of 1971

Abstract

The problem of year to year variability of tropical rainfall attracts much attention in the wake of occurrence of severe floods and droughts over large areas. The severe drought That prevailed in the Sudano-Sahe1ian regions of Africa during the early seventies is the point in mind. Many studies have been carried out in an attempt to understand the possible causes of the Sudano-Sahelian drought. In the study we attempt to perform an investigation on the atmospheric conditions that prevailed in the African troposphere during the northern summer, the rainy months in the Sudano-Sahelian region, of 1971. To achieve this we investigate the mean meridional, zonal motions, temperature fields, atmospheric fluxes of water vapour, angular momentum and sensible heat over African during northern summer of 1971. The results obtained from this study are contrasted with seasonal patterns over the year. The work involved utilization of upper air data for 76 stations made available from some.of the African countries and data extracted from daily charts prepared at the Regional Meteorological Center Nairobi for the period June, July-and August 1971. The results concerning the zonal wind show large positive westerly anomaly at 850 mb in June, July and August; at 700 mb in July and August and at 500 mb in August between 5~S - 10~N. Also large positive easterly anomaly is observed at 400 - 100 mb over central parts of the continent at 3-5 mainly in July and August as the intensity of the tropical Easterly Jet increases in the area