Indian Ocean Low Clouds during the Winter Monsoon

Abstract

While low-level clouds over the Pacific and Atlantic Oceans have been investigated extensively, low clouds over the Indian Ocean are not as well characterized. This study examines the occurrence of nonoverlapped low clouds over the Indian Ocean during the northeast monsoon using several sources of data. Climatologies derived from surface observations and from the International Satellite Cloud Climatology Project are reviewed. Another cloud climatology is developed using infrared and visible imagery from the Indian geostationary satellite. The new climatology has better spatial and temporal resolution than in situ observations. The three datasets are generally consistent and show several persistent features in the cloud distribution. During January?April, maxima in the occurrence of low clouds occur at subtropical latitudes over the Arabian Sea, the Bay of Bengal, the China Sea, and the southern Indian Ocean. The predominant types of low clouds differ in the northern and southern areas of the Indian Ocean region and China Sea. The Arabian Sea and the Bay of Bengal are covered mostly by cumulus clouds, while the southern Indian Ocean and the China Sea are covered mostly by large-scale stratiform clouds such as stratocumulus. These observations are consistent with atmospheric analyses of temperature, humidity, and stability over the Indian Ocean.