Indian ocean low clouds during the winter monsoon

While low-level clouds over the Pacific and Atlantic Oceans have been inves tigated extensively, low clouds over the Indian Ocean are not as well chara cterized. This study examines the occurrence of nonoverlapped low clouds ov er the Indian Ocean during the northeast monsoon using several sources of d ata. Climatologies derived from surface observations and from the Internati onal Satellite Cloud Climatology Project are reviewed. Another cloud climat ology is developed using infrared and visible imagery from the Indian geost ationary satellite. The new climatology has better spatial and temporal res olution than in situ observations. The three datasets are generally consist ent 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 s outhern Indian Ocean. The predominant types of low clouds differ in the nor thern and southern areas of the Indian Ocean region and China Sea. The Arab ian Sea and the Bay of Bengal are covered mostly by cumulus clouds, while t he southern Indian Ocean and the China Sea are covered mostly by large-scal e stratiform clouds such as stratocumulus. These observations are consisten t with atmospheric analyses of temperature, humidity, and stability over th e Indian Ocean.