ABSTRACT

The upper ocean response of Bay of Bengal to two extremely severe post-monsoon tropical cyclones, Phailin and Hudhud, which occurred in the same time of the season (4–12 October 2013 and 6–12 October 2014 respectively) with very similar tracks and life cycles are presented in this study. It is observed that, even though the tropical cyclone Phailin was much stronger than tropical cyclone Hudhud, the cooling of the underlying ocean was more rapid and intense during the passage of tropical cyclone Hudhud. Heat budget analysis of the upper ocean based on realistic simulations using Regional Ocean Modeling System suggests that, while the vertical processes, horizontal advection and the reduction in the net heat flux have contributed to the cooling of the upper ocean in both the cases, the intensity of vertical processes were relatively weaker in the case of tropical cyclone Phailin. Further analysis shows that the surface layers of Bay of Bengal were relatively more stable in October 2013 due to excess rainfall in the preceding summer monsoon compared to October 2014, which was succeeded by a poor monsoon.

摘要

孟加拉湾对两个极端严重的季风后热带气旋 Phailin 和 Hudhud 的上层海洋响应，它们发生在季节的同一时间（分别为 2013 年 10 月 4 日至 12 日和 2014 年 10 月 6 日至 12 日），具有非常相似的轨迹和本研究介绍了生命周期。据观察，尽管热带气旋费林比热带气旋胡德强得多，但在热带气旋胡德过境期间，下层海洋的冷却速度更快、强度更大。基于使用区域海洋建模系统的实际模拟对上层海洋的热收支分析表明，虽然垂直过程、水平平流和净热通量的减少在这两种情况下都有助于上层海洋的冷却，在热带气旋 Phailin 的情况下，垂直过程的强度相对较弱。进一步分析表明，与 2014 年 10 月之后的弱季风相比，孟加拉湾的表层在 2013 年 10 月由于前一夏季风的降雨过多而相对更加稳定。