INVESTIGATION OF CLOUDS AND CLOUD RADIATIVE FORCING ON THE WINDWARD SIDE OF THE MADAGASCAR MOUNTAIN CHAINS

Abstract. Clouds affect the radiative energy balance of the earth–atmosphere system by reflecting and trapping the radiation. The cooling occurs over the earth by reflecting the incoming solar radiation and warming by trapping the outgoing longwave terrestrial radiation. In this paper an attempt has been carried out to understand the clouds and cloud radiative forcing over the windward side of the Madagascar mountain chain. The study was carried out using the Clouds and Earth’s Radiant Energy System (CERES) data June–September from 2000 to 2016. Over the windward side, clouds tend to cool whereas on the leeward side, clouds tend to warm marginally. During this period, peak value of shortwave cloud forcing and the longwave cloud forcing are −45 W m−2 and +15 W m−2 respectively. Generally, the clouds are restricted to low level in the windward side. We also examined the association between the cloud radiative forcing and cloud physical properties such as cloud optical depth, cloud, cloud top temperature and cover amount. The cloud optical depth (−0.74 correlation value) and cloud cover amount (−0.51 correlation value) show better correlation with net cloud radiative cooling. The surface pressure of the Madagascar is also correlated with the net cooling over the windward side.