Subsurface equatorial zonal current in the eastern Indian Ocean
Subsurface equatorial zonal current in the eastern Indian Ocean
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DOI：
10.1029/2008jc005188
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发表时间：
2009-06-09
影响因子：
3.6
通讯作者：
Mizuno, Keisuke
中科院分区：
文献类型：
--
作者：
Iskandar, Iskhaq;Masumoto, Yukio;Mizuno, Keisuke
利用2000年12月至2006年11月在南纬0度、东经90度处锚泊的声学多普勒海流剖面仪（ADCP）观测资料，研究了赤道东印度洋次表层纬向流的变化。分析表明，在北半球冬季和夏季之间的90和170米深度的东赤道次表层电流的存在。在北半球冬季，东向压力梯度的产生，驱动东向流动的温跃层，主要是由上涌赤道开尔文波盛行东风激发。另一方面，下降的Rossby波所产生的反射春季下降的开尔文波在东部边界，以及上升的赤道开尔文波触发东风，创造一个海洋状态，有利于产生的向东的压力梯度在北方夏季。次表层海流具有明显的季节不对称性。最大东移速度出现在4月，为63 cm s（-1），次大东移速度出现在10月，为49 cm s（-1）。次表层流深度内单位宽度的纬向输送也表现出类似的变化：4月份达到最大向东输送量35 m2 s（-1），10月份达到次大值29 m2 s（-1）。此外，在北方夏季的次表层电流经历了显着的年际变化，它是在2003年缺席，但在2006年是非常强大的。
Variations of subsurface zonal current in the eastern equatorial Indian Ocean are investigated by examining 6-year data (December 2000-November 2006) from acoustic Doppler current profiler (ADCP) mooring at 0 degrees S, 90 degrees E. The analysis indicates the presence of an eastward equatorial subsurface current between 90 and 170 m depths during both boreal winter and summer. During boreal winter, the generation of eastward pressure gradient, which drives an eastward flow in the thermocline, is caused primarily by upwelling equatorial Kelvin waves excited by prevailing easterly winds. On the other hand, the downwelling Rossby waves generated by the reflection of the spring downwelling Kelvin waves in the eastern boundary, as well as the upwelling equatorial Kelvin waves triggered by easterlies, create an oceanic state that favors the generation of the eastward pressure gradient during boreal summer. The subsurface current reveals a distinct seasonal asymmetry. The maximum eastward speed of 63 cm s(-1) is observed in April, and secondary maximum of 49 cm s(-1) is seen in October. The zonal transport per unit width within depth of the subsurface current exhibits similar variations: reaching maximum eastward transport of 35 m 2 s(-1) in April and secondary maximum of 29 m 2 s(-1) in October. Moreover, the subsurface current during boreal summer undergoes significant interannual variations; it was absent in 2003, but it was anomalously strong during 2006.