中文摘要：

利用中国科学院“实验1”号调查船2010-2012年东印度洋3个航次的走航断面观测数据,分析了春季孟加拉湾南部和赤道东印度洋上层海洋的水文结构特征,同时结合卫星遥感资料和世界海洋图集2009（world ocean atlas 2009, WOA09）气候态温、盐资料,探讨了孟加拉湾南部海水经向地转输运的变化以及温跃层的波动。结果表明,在3-5月份,即印度洋冬季风向夏季风转换期间,赤道西风的爆发成为这一海域最关键的驱动力,将阿拉伯海的高盐水向东输运,使赤道纬向压强梯度力转为西向,减弱了赤道潜流并引起向北的经向地转输运。在孟加拉湾湾口,赤道的波动强迫导致了经向输运由南向转为北向,来自阿拉伯海的高盐水与孟加拉湾的低盐水在此汇集,形成了明显的盐度梯度；波动强迫还使得孟加拉湾湾口呈现出一个向西移动并减弱的气旋涡流场。在波动和表层盐度差异的影响下,湾口温跃层维持着向西下倾斜的状态,即使是在印度洋东岸海水堆积时,也没有显示出如赤道断面温跃层那般的大幅度加深。

英文摘要：

Using the data collected during 2010~2012 Eastern Indian Ocean （EIO） cruises, we analyzed the hydrographical features in the upper layer of the southern Bay of Bengal （BoB） and eastern equatorial Indian Ocean （EEIO） during spring monsoon transition. We also studied the variations of meridional geostrophic transport and the thermocline at the mouth of the BoB. The results show that the equatorial westerly wind bursts become the dominant force in this region during spring intermonsoon transition around March-May. They change the equatorial pressure gradient force from eastward to westward by transporting the Arabian Sea water to the east, and weaken the equatorial undercurrent. At the BoB mouth, the wave propagation in the equator enhances the northward water volume transport, mixes the water masses form the Arabian Sea and BoB, and increase the salinity gradient. In addition, the remote forcing of equatorial waves leads to the formation of a cyclonic eddy at the BoB mouth. The remote forcing also deepens the thermocline at the west end in the southern BoB, while the upper-layer low salinity water keeps it shallow at the east end even though the thermocline in the EEIO is deepened.