Characteristics of cirrus clouds observed at a low latitude tropical coastal station, Trivandrum using lidar

Abstract

High altitude cirrus clouds at about 1-2 km below the tropopause were observed using the multiwavelength lidar system located at a tropical coastal station, Trivandrum (8°33<i>'</i>N, 77°E). Seasonal variations of these clouds were studied over a period of one year. The clouds were seen almost 50% of the time of lidar operation. An analysis of lidar data has shown frequent occurrence of such clouds near the tropopause. Based on their optical depth, cirrus clouds were c1assitied into two categories, namely thick cirrus (optical depth > 0.03) and thin cirrus (optical depth < 0.03) and their occurrence frequencies were about 64% and 36% of the total occurrences.