| dc.description.abstract | The Bay of Bengal in the northern part of the Indian Ocean is often hit by tropical cyclones. Due to the high density of local coastal populations and mostly low-lying muddy land, cyclone storm surges caused by tropical cyclones often cause severe damage to the local area. For example, the cyclone storm surge triggered by Cyclone Bhola in the Bay of Bengal in 1970 caused nearly 500,000 deaths, making it the tropical cyclone with the highest death toll in human history. This research aims to develop a cyclone storm surge calculation system suitable for the Indian Ocean based on Taiwan’s COMCOT-SS storm surge forecasting system. Since tropical cyclones in the Indian Ocean are different in structure and intensity from typhoons in the Pacific and hurricanes in the Atlantic, the development of parametric wind fields and storm surge models suitable for tropical cyclones in the Indian Ocean is the focus of this research.
This study adopts 5 historical cases (Cyclone Amphan in 2020, Cyclone Fani in 2019, Cyclone Titli in 2018, Cyclone Hudhud in 2014, and the 2013 Cyclone Phailin), to analyze the accuracy of 3 parametric wind fields, as well as NCEP atmospheric models in the generation of cyclone storm surges. Based on the Holland (2010) model, this study obtained peakness parameters B=0.742 which performs well in these 5 historical cases by comparing the model results with the observation data. This B value is different from the usual B value applicable to the Pacific and Atlantic oceans. It also indicates that the structure of the cyclone wind field in the Indian Ocean is different from the Pacific ocean’s typhoon and the Atlantic ocean’s hurricane.
At the end of this paper, a case study of Cyclone Bhola in 1970, the most serious storm surge event in the world, is carried out by using the parameterized wind field and COMCOT-SS storm surge model. In this case, only the cyclone track, the minimum pressure, and maximum wind speed are recorded. Therefore, two scenarios, atmospheric pressure prioritize, and wind shear stress prioritize, are used for event reconstruction. In the scenario of atmospheric pressure prioritize, the impact area of the tropical cyclone is relatively small, and the inland overflow caused by storm surge covers Kuakata, Burir Char, Patharghata, and other coastal areas south of Barisal, Bangladesh. However, in the scenario of wind shear stress prioritize, the impact area is relatively large, and the flooding area reaches as far as Patuakhali, Bangladesh. Detailed information can be found in the content. | en_US |