斯里兰卡穹顶区的形成和演变机制分析

通过SODA再分析资料和AVISO观测资料研究了斯里兰卡穹顶区（SLD）的迁移和消散机制.斯里兰卡穹顶区是孟加拉湾西南部的一个气旋涡旋，主要出现在西南季风（5-9月）期间，与西南季风海流侵入孟加拉湾同时存在.正风应力旋度引起的Ekman抽吸是形成SLD的主要原因.回归分析结果表明SLD区域的风应力旋度与Ekman抽吸存在较强的正相关（r²=0.93，p>0.5）.此外，结果表明SLD在发展过程中的移动主要受正风应力旋度移动的影响，SLD的消减与该正风应力旋度减弱和西传的暖Rossby波有关，而冷Rossby波的传播有益于SLD的发展.在SLD消减时期，孟加拉湾涡旋（BBD）独立发展并进一步与SLD融合，回归分析发现BBD区域的Ekman抽吸与当地风应力旋度的关系密切（r²=0.76，p>0.5），这表明了BBD在形成阶段由局地的风应力主导.9月之后，风应力旋度减弱，BBD和SLD开始了合并过程.动力方面，EKE分析显示SLD衰退的同时，BBD的EKE大幅增加；热力方面，10-11月时，由Ekman抽吸引起的SLD和BBD次表层冷水汇合，清晰地表明了二者之间的热动力学联系.

Mechanisms of the Sri Lanka Dome and its evolutionary aspects

This study focuses on the formation,migration and dissipation mechanisms of the Sri Lanka Dome (SLD) and its combination with Bay of Bengal Dome (BBD) using Simple Ocean Data Assimilation reanalysis data and AVISO data.The SLD is a cyclonic eddy in the southwest Bay of Bengal,which occurs during May through September coinciding with the intrusion of southwest monsoon current into the Bay of Bengal.The results show that,Ekman pumping due to positive wind stress curl east off Sri Lanka is the governing mechanism of the SLD formation and migration during developing stage.Besides,a positive impact of cold Rossby waves propagation contribute to the SLD developing as well.Further,weakening positive wind stress curl and the eastern boundary reflected warm Rossby wave effect are important factors for dissipation of SLD.During the decaying stage of SLD,the BBD evolves independently because of the Ekman Pumping driven by local positive wind curl.The regression analysis proves that the local wind stress curl has a strong positive relationship with upwelling within the BBD.After September,weak positive wind stress curl dominates in the southwest BOB,the BBD starts to merge with the SLD.There are two kinds of links between SLD and BBD.The first is a dynamic interaction revealed by eddy kinetic energy analysis and the second is a thermodynamic interaction described by combination of subsurface cold cores of the SLD and the BBD.