南印度洋表层副热带环流的漂流示踪  

Subtropical surface circulation in the southern Indian Ocean derived from surface drifters

作　　者：张涟漪[1,2] 杜岩[1] 郑少军[1] 贺志刚[3] 彭世球[1] 

机构地区：[1]中国科学院南海海洋研究所热带海洋环境国家重点实验室,广州510301 [2]中国科学院大学,北京100049 [3]厦门大学近海海洋环境科学国家重点实验室,厦门361005

出　　处：《科学通报》2016年第33期3596-3605,共10页Chinese Science Bulletin

基　　金：国家自然科学基金(41525019;41306018;41521005);中国科学院战略性先导科技专项(XDA11010103);国家海洋局"全球变化与海气相互作用"专项(GASI-IPOVAI-02);热带海洋环境国家重点实验室(LTO)自主项目(LTOZZ1501);国际合作创新研究项目(CAS/SAFEA)资助

摘　　要：基于历史表层漂流浮标数据,利用轨迹跟踪方法分析了南印度洋表层副热带环流的平均态特性.浮标路径反映出南印度洋海水由高纬向低纬输运的过程大体可分为2种:海水沿南印度洋东边界北上,汇入南赤道流后绕过马达加斯加岛北侧,沿非洲东岸跨越赤道进入北半球;或者由南印度洋中部北上,受南赤道流影响转向,到达马达加斯加岛东部后返回南印度洋构成副热带环流.漂流浮标获得的流速和能量结果表明,部分海区流的空间变率十分显著,如阿古拉斯回流区、马达加斯加北部、南印度洋西部海盆和澳大利亚西侧海区等.特别地,虽然可能受到如季节变化和涡旋扰动等因素的干扰,在漂流浮标拉格朗日式的观测下没有发现显著的副热带逆流,但是可以通过平均动能和涡动能分布观察到逆流的微弱特征.此外,基于浮标示踪,还反推留尼汪岛附近漂流浮标的可能来源,得到其沿南副热带环流的3种移动路径,这对海上搜索具有现实指示意义.Using trajectory tracing method from 308 long-lived surface drifters, the subtropical surface circulations in the southern Indian Ocean（SIO） are investigated in the views of both Lagrangian and Euler. Analysis of the results from the Lagrangian view confirm the two pathways of seawater transport from high to low latitude based on different types of drifter trajectory. One pathway is that the seawater formed in high latitude flows northward along the eastern boundary of SIO, joints the westward South Equatorial Current（SEC）, and reaches east of the Mozambique along the north side of the Madagascar Island, then bifurcates into northward and southward branches： the northward branch cross the equator and finally joints the north Indian Ocean circulation system; the southward branch meanders along the Mozambique Channel and forms a series of mesoscale eddies. The other pathway is that the seawater flows northward through the central SIO, then turns to west following the SEC, and flows back to the south when reaches the east of the Madagascar Island. Based on the trajectory of drifters, the mean life cycle of subtropical circulation is about 43±20 months. In Euler view, zonal and meridional velocity, mean kinetic energy（MKE）, and eddy kinetic energy（EKE） are calculated in 0.5°×0.5° grid using Poulain＇s method. The high MKE reaches over 1000（cm/s）2 in the regions of South Equatorial Current, Agulhas Current/Agulhas Return Current, Eastern Madagascar Current, and Eastern African Coastal Current, the two latter of which are western boundary currents. The EKE has similar spatial distribution with the MKE in the region west of Australia. The spatial variations of current in several areas are significantly modulated by mesoscale eddies, such as in the regions of Agulhas Retroflection, western basin of SIO, and west of Australia. Agulhas system, especially in the area of Agulhas Retroflection, has highest MKE and EKE, due to the interaction with the bottom topography and the wind stress curl induce

关 键 词：漂流浮标 南印度洋 副热带环流 海上搜索 MH370 

分 类 号：P731.27[天文地球—海洋科学]