基于CTD资料的南海南部上层环流结构分析

利用2009-2012年南海南部海域4个调查航次的CTD资料,计算了南海南部海域的动力高度,分析了季风转换期南海南部上层的环流结构。结果表明:2009年夏初(6月),调查区上层环流结构已经初具夏季形态,越南离岸流已明显出现;2010年秋末冬初(11月),上层环流结构基本转换为冬季环流形态,越南离岸流消失,纳土纳流出现;2011年秋季中期(10月),南海南部的环流处于夏季向冬季转换形态,越南离岸流减弱,但调查区域夏季的反气旋式环流依然存在;2012年9月夏末秋初,南海南部的环流仍然与夏季的形态相近,越南离岸流依然存在,其两侧的环流结构也与夏季相同。本文的分析结果还较为清晰地给出了南海南部环流由夏季向冬季转变的动态过程。

Observational study on the upper layer circulation in the southern South China Sea based on CTD data

Conductivity-temperature-depth data from four cruises spanning 2009 to 2012 are used to investigate the structure of the upper layer circulation in the middle and southern South China Sea(SCS) during the monsoon transition. In the late spring,2009,the upper structures of the middle and southern SCS have begun to take the summer circulation structure and the Southeast Vietnam Offshore Current(SVOC) has been evident. In November 2010,the dynamic heights in the middle and southern SCS show that the upper structures of the middle and southern SCS have converted to the winter pattern. In this period,the SVOC has been vanished and the Natuna Off-Shelf Current(NOC) has been evident. In October 2011,the structures of the SCS were converting to the winter pattern from the summer characterized by the reductions of the SVOC,but the anticyclonic circulation in the summer pattern still existed. In September 2012,the upper structures of the middle and southern SCS have been similar to the summer pattern mainly be seen in the existed of the SVOC and the structures of the circulation were the same as the summer pattern on either sides of the SVOC. In addition,the analysis results also clearly shows the changing of the circulation of the middle and southern SCS from summer to winter.