Study of Rainfall Distributions over Bangladesh associated with Tropical Disturbances in the Bay of Bengal

Abstract

Tropical cyclone is the most disastrous natural phenomenon for Bangladesh. Only preparedness can reduce the losses of lives as well as properties. Rain, one of the three means of destruction due to Tropical cyclone, is closely related with the Tropical cyclone. From its birth to death tropical cyclone produces rain, but the amount and region of rainfall at different stage of the tropical cyclone is different. Keeping this information in mind, in this dissertation, we have studied the rainfall distribution over Bangladesh with the movement of the tropical disturbances in the Bay of Bengal that crossed the Bangladesh coast. As our interest was limited over Bangladesh only, we have chosen those events whose eventual landfall was in the Bangladesh coast from the database created with the help of Bangladesh Meteorological Department (BMD). The main objective of this study is to identify the relationship between the amount of rainfall that is observed in different meteorological stations all over Bangladesh and the track of the tropical disturbances affecting Bangladesh. For that purpose rainfall data of 30 stations located all over Bangladesh is analyzed. We have plotted the isolines to identify the rainfall pattern over Bangladesh map along with the track of the disturbances. Then these figures are analyzed to identify the relationship between the rainfall and the track of the disturbances. In this study, 17 cyclonic disturbances of different categories, 8 Severe Cyclonic Storms with a core of hurricane wind (SCS (H)), 2 Severe Cyclonic Storm (SCS), 3 Cyclonic Storm (CS), 3 Deep Depression (DD) and 1 depression, have been considered that occurred during 1974 to 2001. The analysis shows that heavy to very heavy rainfall occurred on the front-right quadrant of the track on the day and the day before the system approached the Bangladesh coast.