东南印度洋各锋位置和走向的季节变化及其与风场变化的关系

Seasonal variations of the front paths and wind field in the Southeast Indian Ocean and their relations

利用剖面浮标的温盐观测资料和上层温度观测资料以及ECCO风应力数据研究了东南印度洋各主要海洋锋的位置、走向和风场的季节变化，并初步分析了亚热带锋（STF）和亚南极锋（SAF）的成锋机制．季节平均的夏季和冬季厄加勒斯锋（AF）分别可以延伸到80°E和82°E，AF在多数情况下可能与SAF和南亚热带锋（SSTF）汇合共同通过Kerguelen—Amsterdam Passage．在克尔盖伦海台以东海盆区，冬季SAF和PF的路径均比夏季偏南，在其他海域二者路径的季节差别不大．克尔盖伦海台以东的深海盆由北向南正负风应力旋度高值中心交替出现，且位置季节变化很小．85°～105°E之间零风应力旋度线位置冬季比夏季偏北．STF位于辐聚区，埃克曼抽吸导致的表层水辐聚可能是STF产生和维持的原因．SAF位置的季节南北摆动幅度小于风应力零旋度线的季节摆动幅度，夏季SAF位置略偏于风应力正旋度区，而冬季大多位于负旋度区，因此风应力旋度不是SAF形成的直接原因．

Temperature and salinity measured by profile floats, upper layer temperature and ECCO wind stress field were used to study the seasonal variations of the front paths and wind stress field in the Southeast Indian Ocean and analyze the frontogenesis of Subtropical Front （STF） and Subantarctic Front （SAF） preliminarily. We found that the seasonally averaged Agulhas Front （AF） can extend to 80°E and 82°E in summer and winter, respectively. In most cases AF, SAF and South Subtropical Front （SSTF） converge and pass through Kerguelen-Amsterdam Passage as one front. The paths of SAF and PF are more southward in winter than those in summer in the downstream deep basin of Kerguelen Plateau. Positive and negative wind stress curl core appear alternately from north to south right downstream of Kerguelen Plateau. The zero wind stress curl is more northward in winter than in summer between 85°E and 105°E. STF locates at the area within the convergence. Ekman pumping in this area results in the convergence of surface water, which could cause the formation of STF and help to maintain it. The seasonal shift of SAF is less than that of zero wind stress curl, which causes that SAF locates at the area with weak positive wind stress curl in summer while at the area with negative wind stress curl in winter and means that wind stress curl is not the directly external cause of the SAF frontogenesis.