Intraseasonal Variations of Cloud Amount and Rainfall
in Bangladesh and Its Surrounding Area

Md. Syeeduzzaman Kamal

Bangladesh is located in the Indian summer monsoon region and is characterized by especially huge rainfall amount. In this paper, the intraseasonal variations of cloud amount and rainfall in Bangladesh and its surrounding area were examined by using the cloud amount data of Geostationary Meteorological Satellite (GMS) from January 1983 to December 1992 and daily rainfall data of Bangladesh Meteorological Department in 1990. The analyses were made not only in summer monsoon season but also in other season. Main results are as follows:
1) The clear intraseasonal variations of coud amount were observed in all of these years, even in spring and autumn, and the time variation of about 30-day period appears as a predominant mode.
2) The amplitude of intraseasonal variations of cloud amount in Bangladesh is larger in nin-summer season than in summer. But it is large even in summer in the case of upper-level cloud amount.
3) The time variation of rainfall in the southern part of Bangladesh occured in close association with the intraseasonal variation of upper-level cloud amount in spiring and autumn.
4)Although the intraseasonal variation of cloud amount was observed in the equatorial region in non-summer season, it shows little relation to that in the Bangladesh region in spring.
Finally the discussions on rain-producing systems associated with intraseasonal variation are made.