Distribution of global and net solar radiation over the Indian Ocean

Abstract

Annual and monthly maps showing the distribution of global solar and net solar radiation over the Indian Ocean and its adjoining land areas have been prepared from available observations, supplemented by calculations based on observations of albedo, duration of sunshine and cloudiness. The annual distribution of global solar radiation shows minima over the equatorial belts and the monsoon regions and maxima over the subtropical high pressure areas. 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.

The net solar radiation is naturally smaller than global radiation but its distribution pattern is very similar to that of global radiation, with maxima along the subtropics and minima along the equator. The major differences arising from the different values of surface albedo over land and sea, are the location of maxima over sea in the subtropics, with the highest values in north Arabian Sea, and breaks in the isolines between sea and land.

Over the Indian Ocean itself, the latitudina1 variation of both global and net solar radiation is small during the southern summer but large during the northern summer. The pattern shifts with the movement of the sun, the most prominent feature being the distortion of the basic distribution pattern during the monsoon season over India and, southeast Asia, during the northern summer.