The present study examines the tropical cyclones (TCs) activity over the Bay of Bengal (BoB) during post-monsoon season (October–December) for the period 1972–2015 (44 years period). The study has explored the active and inactive TC years on the basis of mean ±1 standard deviation, respectively. A total of nine active (when TCs frequency is ≥4 in a year) and 18 inactive (when TCs frequency is ≤1 in a year) TC years have been identified during the 44 years period. The mean frequency of TCs during the active TC years (4.22 TCs/year) is approximately five times higher than the inactive TC years (0.78 TCs/year). These active and inactive TC years have shown association to some extent with El Niño-Southern Oscillation and Indian Ocean Dipole events. Various environmental factors influencing the occurrence of TCs have been investigated, by analyzing the composites of nine active and 18 inactive TC years. Further, the existence of more precipitable water, strong convective activities, less sea level pressure, reduced vertical wind shear, upper-level easterly winds and high low-level cyclonic vorticity have provided favourable conditions for the TCs genesis during the active TC years.

本研究调查了1972-2015年（44年）的季风后季节（10月至12月）在孟加拉湾（BoB）上的热带气旋（TCs）活动。该研究分别基于平均值±1标准偏差探索了活动和不活动的TC年。在这44年中，总共确定了9个活动（当TCs频率≥4时）和18个不活动（当TCs频率≤1时）的TC年。活动TC年（4.22 TCs /年）期间TC的平均频率大约是非活动TC年（0.78 TCs /年）的五倍。这些活跃和不活跃的TC年在一定程度上显示出与厄尔尼诺-南方涛动和印度洋偶极子事件有关。研究了影响TC发生的各种环境因素，通过分析9个活动和18个非活动TC年的组合。此外，存在更多的可降水量的水，强的对流活动，较低的海平面压力，减小的垂直风切变，较高的向东风和较高的低空旋风涡度为活跃的TC年代的TCs形成提供了有利条件。