Distribution of global and net radiation over the Indian ocean and its environments

Abstract

Maps showing the distribution of global solar, net terrestrial and net radiation over the Indian Ocean area have been prepared from available observations, supplemented by calculations based on other meteorological measurements. Annual and monthly maps for four representative months January, April, July and October for global solar and net radiation are presented. Global solar radiation shows minima over the equatorial and monsoon regions, and maxima over land in the high pressure belts of the northern and southern hemispheres along the tropics of Cancer and Capricorn, the highest values of the order of 220 kcal/cm²/year occuring over North Africa and Arabia. While there is very little latitudinal variation over the ocean during the southern summer, the variations are marked during the northern summer. The geographical distribution is mainly zonal except in the low latitudes, where areas of higher or lower radiation are distributed according to regions of higher or lower amounts of cloudiness. Net radiation over the ocean is always positive and greater than that on land. The distribution is mainly zonal, maxima occuring over the sea in the tropics, with the highest values in the North Arabian Sea and the ocean areas to the northwest of Australia. Minima occur over land in the arid regions of both hemispheres and in the monsoon areas where global solar radiation itself is low. There is very little variation over the ocean during the southern summer but variations are large during the northern summer.