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.