Abstract The east coast of India is highly prone towards the devastation by the cyclonic storms. The Bay of Bengal (BoB) basin in the northeastern Indian Ocean is characterized to provide adequate conditions to the cyclogenesis. The cyclogenesis is more active during pre- and post-monsoon seasons over the BoB. The post-monsoon season shows highest storm occurrence in the region due to presence of warm and freshwater in the upper-ocean which helps to maintain deep barrier layer and supports cyclogenesis. The very severe cyclonic storm, Hudhud was a post-monsoonal storm occurred during 07th–14th October 2014 over the BoB. Hudhud made landfall near Visakhapatnam coast at noon of 12th October 2014. The present study utilized a three dimensional coupled bio-physical model for the analysis of biogeochemical response of the upper-ocean to Hudhud cyclone. The different surface and subsurface physical and biological features along the track of Hudhud has depicted a cyclone-generated surface phytoplankton bloom and its associated decline of surface dissolved oxygen. The study aims at a better understanding of the spatial and temporal variability of the upper-ocean parameters in response to the passage of tropical cyclone (TC) Hudhud. It is found that the intense cyclonic wind stress caused upwelling in the wake of cyclone track about 1550 km from its genesis location. The excess surface freshwater flux due to precipitation establishes stronger stratification in the coastal region. This enhanced stratification found to restrict the supply of nutrients to the euphotic zone and, hence, limiting the surface primary productivity in the coastal region.

中文翻译：

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与 Hudhud 气旋相关的上层海洋物理和生物特征：生物物理模型研究

摘要 印度东海岸极易遭受气旋风暴的破坏。印度洋东北部的孟加拉湾 (BoB) 盆地的特点是为气旋发生提供了足够的条件。在 BoB 的季风前和季风后季节，气旋形成更加活跃。季风后季节显示该地区风暴发生率最高，因为上层大洋中存在温暖和淡水，有助于维持深层屏障层并支持气旋发生。非常严重的气旋风暴 Hudhud 是 2014 年 10 月 7 日至 14 日在 BoB 上空发生的季风后风暴。Hudhud 于 2014 年 10 月 12 日中午在维沙卡帕特南海岸附近登陆。本研究利用三维耦合生物物理模型来分析上层海洋对 Hudhud 气旋的生物地球化学响应。Hudhud 轨道沿线的不同地表和地下物理和生物特征描述了气旋产生的地表浮游植物大量繁殖及其相关的地表溶解氧下降。该研究旨在更好地了解上层海洋参数在响应热带气旋 (TC) Hudhud 的通过时的空间和时间变化。研究发现，强烈的气旋风应力在距其起源位置约 1550 公里的气旋轨迹后引起了上升流。由于降水造成的过量地表淡水通量在沿海地区建立了更强的分层。发现这种增强的分层限制了对富光区的营养供应，因此限制了沿海地区的地表初级生产力。