Typical Surface Seasonal Circulation in the Indian Ocean Derived from Argos Floats
ZHENG Shao-Jun,ZHANG Yu-Hong,ZHUANG Wei,LI Jia-Xun,DU Yan
State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301;State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301;State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301;Second Institute of Oceanography, State Oceanic Administration, Hangzhou 310012;State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301
This study investigates the surface circulation in the Indian Ocean using Argos float data over the period 1979–2011. The Argos observations manifest some new phenomena. The climatological annual mean circulation shows that the surface current becomes much stronger after turning around in shore in the western Indian Ocean. In the tropical Indian Ocean, the Great Whirl (GW) to the east of Somalia develops quickly in spring (April-May) as the monsoon reverses to move northward, becoming strongest in summer (June–September) and disappearing in autumn (October-November). The west end of the Agulhas retroflection can reach 18°E, and it exhibits a seasonal variation. At approximately 90°E, the Agulhas Return Current combines with the eastward South Atlantic Current and finally joins the Antarctic Circumpolar Current.
