吕宋海峡黑潮脱落涡旋的特征分析

涡旋脱落在西太平洋和南海的海水属性交换中起到重要作用。为研究吕宋海峡附近海域由黑潮脱落并进入南海的涡旋特征,本文采用1993—2014年法国空间局(AVISO)多卫星融合海面高度距平(SLA)和绝对动力地形(ADT)全球网格化延时数据,美国国家海洋数据中心(NODC)的WOA13年平均温盐剖面气候数据,以及1993—2010年SODA2.2.4月平均海洋同化数据集,并分析了黑潮脱落涡旋与大尺度环流的关系。结果表明:(1)暖涡脱落数量远多于冷涡数量,且脱落的冷涡绝大部分在黑潮西侧边缘生成,而脱落的暖涡则大部分在黑潮控制区生成。(2)冷涡、暖涡脱落时的平均半径、平均振幅相近,但是冷涡的平均生命、平均迁移距离约为暖涡的一半。(3)冷涡不是每年都有脱落,主要在冬季脱落;暖涡则每年均有脱落,主要发生在秋季。(4)脱落涡旋数量与脱落时的黑潮路径类型相关。(5)脱落涡旋的平均西行速度为5.8cm/s,与斜压第一模态长Rossby波波速及大尺度环流的西向平流流速之和相近。

THE CHARACTERISTICS OF EDDIES SHEDDING FROM KUROSHIO IN THE LUZON STRAIT

The characteristics of eddy shed from Kuroshio in the Luzon Strait area and entering into the South China Sea were studied in statistics. Three datasets were used, i/e., 22-year (1993-2014) of global gridded multi-satellite merged sea level anomaly and absolute dynamic topography products in delay time provided by Archiving, Validation, and Interpretation of Satellite Oceanographic data (AVISO), the climatological annual mean temperature and salinity profiles of World Ocean Atlas 2013 (WOA13) data provided by National Oceanographic Data Center (NODC) and the monthly SODA2.2.4 date set from 1993 to 2010. As compared to cold eddies shed (CEs) in this area, the warm eddies shed (WEs) are much greater in number. The most CEs are formed at the western edge of the Kuroshio, while the most WEs are formed within the Kuroshio-controlled areas. The average radius and average amplitude of CEs and WEs are similar, but the average lifetime and average migration distance of CEs are almost a half of those of WEs. WEs take place in all seasons but mostly in autumn, while CEs do mostly in winter. In addition, the amount of the eddy shedding is related to the path type of Kuroshio at the shedding time. The average westward migration speed of eddy shed is 5.8cm/s, which is close to the sum of the mean baroclinic first phase speed of Rossby wave and that of the mean west component of the large-scale circulation currents.