利用INSTANT(The International Nusantara Stratification and Transport,努沙登加拉层结及输运的国际联合观测计划)计划所测得的流场数据,研究了ITF(Indonesian Throughflow,印度尼西亚贯穿流)在主要流出海峡——龙目海峡(Lombok Strait)、翁拜海峡(Ombai Strait)和帝汶海峡(Timor Passage)随深度和时间的变化,并对表层和温跃层的流速进行了功率谱分析。研究发现,ITF流场在龙目和翁拜海峡表层有显著的年循环,在季风转换期间各个层次上海流都会出现反转,从印度洋流向海峡内;而帝汶海峡在300m以下出现反转流。3个海峡的表层流都以年周期为主,温跃层的流以半年变化为主,并且都有丰富的季节内变化。高频部分,除了在龙目海峡表层K1日潮占优外,各海峡均以M2半日潮为主。
The present study investigates the role of Kelvin wave propagations along the equatorial Indian Ocean during the 2006-2008 Indian Ocean Dipole(IOD).The 2006 IOD lasted for seven months,developing in May and reaching its peak in December,while the 2007 and 2008 IODs were short-lived events,beginning in early May and ending abruptly in September,with much weaker amplitudes.Associated with the above IODs,the impulses of the sea surface height(SSH) anomalies reflect the forcing from an intraseasonal time scale,which was important to the evolution of IODs in 2007 and 2008.At the thermocline depth,dominated by the propagation of Kelvin waves,the warming/cooling temperature signals could reach the surface at a particular time.When the force is strong and the local thermocline condition is favorable,the incoming Kelvin waves dramatically impact the sea surface temperature(SST) in the eastern equatorial Indian Ocean.In July 2007 and late July 2008,the downwelling Kelvin waves,triggered by the Madden-Julian Oscillation(MJO) in the eastern and central equatorial Indian Ocean,suppressed the thermocline in the Sumatra and the Java coast and terminated the IOD,which made those events short-lived and no longer persist into the boreal fall season as the canonical IOD does.
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.
ZHENG Shao-JunZHANG Yu-HongZHUANG WeiLI Jia-XunDU Yan
