Assessment of the Relationship between Passages of Tropical Cyclones and their Origins of Genesis for Managing Risk of the Coast of Bangladesh

To understand risk from upcoming tropical cyclones (TCs) of Bangladesh, Impact of Indian Ocean Dipole (IOD) on origins of TCs genesis historically over Bay of Bengal (BoB) should be considered. So, the correlation between Dipole Mode Indexes (DMI) and frequencies of TCs generated in BoB has been investigated for (1877-2018) era. Changes in decade-wise mean DMI have been found linearly correlated with changes in decade-wise TC frequency. Then, a quadrant reference frame has been used to follow the behavior of TCs origins of genesis of different decades with respect to the changes in decade-wise mean DMI. In the decades having negative (positive) decade-wise mean DMI values, most of TCs generated from the western part (middle and eastern parts) of BoB and had an approach towards the middle (southeastern part) of BoB with the increase of decade-wise mean DMI. In addition, almost all the category 4 TCs (Saffir-Simpson scale) of BoB has been generated from the southeastern part of BoB. Therefore, this study conclude that most of the TCs of upcoming decades might generate from the southeastern part of BoB that may induce more category 4 TCs and have high possibilities to pass through the coasts of Barishal and Chittagong (Chattogram).