The present study explored the role of the pre-existing cyclonic eddy on the chlorophyll-a (Chla) bloom after a cyclone pass over the northern Bay of Bengal (BoB). We used a high-resolution (~9 km) Regional Ocean Modeling System (ROMS) coupled with an established Nutrient-Phytoplankton-Zooplankton-Detritus (NPZD) model. In the study, we have considered cyclone Hudhud (category-4), which passed over a cyclonic eddy in the BoB during 7–12 October 2014. Before the passage of cyclone Hudhud, strong stratification in the upper ocean inhibited eddy-driven upwelling of nutrients to the mixed layer and limited the phytoplankton production. However, when cyclone Hudhud interacted with the cyclonic eddy, which further reduced the water column stability (one order less) of the upper ocean and initiated the wind-driven upwelling. This mechanism resulted in the easy upwelling of cold nutrient-rich water to the mixed layer. A case study presented here demonstrates ocean–atmosphere (eddy-cyclone) interaction and its influence on the mixed layer Chla production in the northern BoB. Our study showed that column integrated Chla value in the upper 100 m increased by 70% when cyclone Hudhud passed over a cyclonic eddy region in the BoB. The present study suggested that cyclonic eddy accompanied by cyclone Hudhud induced the Chla bloom in the Northern Bay during the post-monsoon season of 2014.

本研究探讨了预先存在的气旋涡流对叶绿素 a (Chl a) 气旋经过北孟加拉湾 (BoB) 后绽放。我们使用了高分辨率（约 9 公里）区域海洋建模系统 (ROMS) 以及已建立的营养-浮游植物-浮游动物-碎屑 (NPZD) 模型。在研究中，我们考虑了 2014 年 10 月 7 日至 12 日期间经过 BoB 中的气旋涡旋的飓风 Hudhud（第 4 类）。在飓风 Hudhud 通过之前，上层海洋的强烈分层抑制了涡流驱动的上升流养分进入混合层并限制浮游植物的产生。然而，当飓风 Hudhud 与气旋涡流相互作用时，这进一步降低了上层海洋的水柱稳定性（少了一个数量级）并引发了风力驱动的上升流。这种机制导致富含营养的冷水容易上涌到混合层。一个在鲍勃北方生产。我们的研究表明，当飓风 Hudhud 通过 BoB 中的气旋涡流区时，上 100 m 的柱综合 Chla 值增加了 70%。目前的研究表明，在 2014 年季风后季节，气旋涡旋伴随着飓风 Hudhud 导致了北部湾的叶绿素a绽放。