进入中国南海的黑潮脱落中尺度涡的特征——基于OFES模式数据

自黑潮脱落并由吕宋海峡进入中国南海的中尺度涡(简称脱落涡旋)对黑潮与南海的水体交换、热量及物质输送等过程均有十分重要的作用。基于1993—2013年OFES(OGCM for the Earth Simulator)模式数据产品,分析研究了脱落涡旋的统计特征及其温盐流三维结构,并与卫星观测结果进行对比分析。OFES模式的海表面高度数据和卫星高度计数据的统计结果都表明气旋式脱落涡旋(脱落冷涡)绝大部分在黑潮西侧边缘生成,反气旋式脱落涡旋(脱落暖涡)则大部分在黑潮控制区(包括黑潮流套区)生成,脱落暖涡的数量远多于脱落冷涡的。OFES模式数据得到的脱落涡旋个数和出现频率较卫星观测结果要明显偏低。此外,由OFES模式数据得到的脱落涡旋三维结构表明,黑潮控制区和黑潮西侧边缘生成的脱落冷涡的流场垂向影响深度差异较大,而脱落暖涡的流场垂向影响深度一般达水深1000 m以深,脱落涡旋的位势温度的垂向影响深度与该涡的流场垂向影响深度相当,其盐度的垂向影响深度则较浅;脱落涡旋的温盐结构受黑潮的影响较大。

Characteristics of the Eddies Shed From the Kuroshio into the South China Sea:Based on the OFES Ocean Model Data

The eddies shed from the Kuroshio into the South China Sea are very important for the water exchange,heat and mass transport between the Kuroshio and the South China Sea.Using the OGCM for the Earth Simulator(OFES)ocean model product from 1993 to 2013,we analyze the statistical characteristics and three-dimensional structure of the eddies.Both the OFES and altimeter data show that 1)most of cyclonic eddies were shed from the western edge of the Kuroshio,while most of anticyclonic eddies were formed within the Kuroshio-controlled areas,and 2)the number of the anticyclonic eddies far exceed that of the cyclonic eddies.The number of the eddies and the occurrence frequency of shedding revealed by the OFES sea surface height data are relatively low compared those revealed from the altimetry data.The affected depth by the current anomaly associated with the cyclonic eddies varies with the eddy formation area,while the affected depth related to anticyclonic eddies usually reaches over 1000 m.The affected depth by the potential temperature induced by eddies matches the one affected by the current anomaly,while the depth affected by the salinity is relatively shallower.Analysis also shows that the thermohaline structure of the eddies is greatly affected by the Kuroshio.