The South Equatorial Current (SEC) in the Indian Ocean bifurcates when it reaches Madagascar leading, respectively, to the North East Madagascar Current (NEMC), which contours the island flowing northwestward, and to the South East Madagascar Current (SEMC), which flows southwestward. Both branches eventually contribute to the greater Agulhas Current system and thus play a part in the global ocean circulation. In addition, these currents have important effects on the local conditions for marine life. In this study, the NEMC and the SEMC are investigated based on a comprehensive, multidisciplinary survey of the east coast of Madagascar in 2008. Results from conductivity-temperaturedepth stations, underway measurements with thermosalinograph and fluorometer, and ship-mounted acoustic Doppler current profiler are discussed along with concomitant remotely sensed data. Maximum core velocities of >150 cm s–1 were observed in both the NEMC and the SEMC. The SEMC appeared as a nearshore southward jet, which extended at its widest nearly 200 km offshore. Near the southern tip of Madagascar, the SEMC was flanked by reverse velocities: a northeastward current about 30 km wide along the coast and a northeastward offshore current greater than 140 km wide suggesting the presence of the South Indian Ocean Countercurrent. The NEMC had the structure of a narrow nearshore jet, with weak currents beyond 100 km offshore. Volume transport for the upper 1,100 m was estimated to be 22 Sverdrup (Sv) for the SEMC and 48 Sv for the NEMC. The high NEMC transport compared with earlier estimates might be because of anomalously high influx of the SEC during the measurement period. Off the south coast, an undercurrent below 900 m carried an equatorward transport of 3.1 Sv. No undercurrent was observed in the north, but a geostrophic velocity minimum and a similar vertical velocity shear between surface and subsurface currents were found at the level where such a countercurrent has been previously observed from direct measurements.

中文翻译：

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东马达加斯加洋流系统的观测：动力学和体积输运

印度洋中的南赤道洋流 (SEC) 在到达马达加斯加时分叉，分别通向西北马达加斯加洋流 (NEMC) 和马达加斯加东南洋流 (SEMC)，该洋流环绕该岛向西北流动向西南。这两个分支最终都对更大的阿古拉斯海流系统做出了贡献，从而在全球海洋环流中发挥了作用。此外，这些洋流对当地的海洋生物条件也有重要影响。在这项研究中，NEMC 和 SEMC 是基于 2008 年对马达加斯加东海岸的综合性多学科调查进行的。和船载声学多普勒电流剖面仪以及伴随的遥感数据进行了讨论。在 NEMC 和 SEMC 中都观察到了 >150 cm s-1 的最大核心速度。SEMC 表现为近岸向南喷射，其最宽处延伸到近海近 200 公里。在马达加斯加的南端附近，SEMC 的两侧是逆流：沿海岸约 30 公里宽的东北流和超过 140 公里宽的东北近海流，表明存在南印度洋逆流。NEMC 具有狭窄的近岸喷气机结构，在离岸 100 公里以外有微弱的水流。上部 1,100 m 的体积输运估计为 SEMC 的 22 Sverdrup (Sv) 和 NEMC 的 48 Sv。与早期估计相比，高 NEMC 传输可能是因为在测量期间 SEC 的异常高流入。在南海岸，低于 900 m 的暗流携带了 3.1 Sv 的赤道输送。在北部没有观察到暗流，但在先前通过直接测量观察到这种逆流的水平，发现了地转速度最小值和地表和地下流之间类似的垂直速度切变。