东海陆架区中尺度涡运动路径的统计特征分析

基于1993—2017年卫星高度计海面高度异常中尺度涡旋追踪数据集,对东海陆架区及从西北太平洋入侵东海的涡旋进行路径分类、季节变化及特征参量统计分析,并结合再分析流场资料,进行背景流场、涡度场分析。研究结果显示,近25 a,在东海追踪到318个气旋涡和276个反气旋涡。根据涡旋运动路径将其分为:东海陆架浅海生成往深海传播型(148个)、深海生成向东海陆架浅海传播型(35个)、沿等深线运动型(180个)、徘徊型(121个)、外来入侵到达东海陆架型(25个)及外来入侵到达东海深海型(85个)。6类涡旋的数量存在明显的季节分布,各个类型气旋与反气旋涡数量的季节分布也各不相同。其中,沿等深线运动型涡在春、夏季的数量高于秋、冬季。陆架浅海区生成往深海运动型涡的季节分布较为平均,气旋式涡在夏季数量最少,在春季和冬季数量较多。黑潮与涡旋数量的季节分布有关。徘徊型涡的平均生命周期最长,约为44 d;陆架浅海生成往深海运动型及外来入侵到达东海陆架的中尺度涡具有最大的平均振幅,为13.2 cm;外来入侵到达东海陆架型涡具有最大的直径,为122 km;外来入侵到达东海深海型涡在进入东海后的生命周期、振幅、直径在数值上均为最小。

Statistical characteristics and path analysis of mesoscale eddy in the East China Sea

An Archiving Validation and Interpretation of Satellite Oceanographic(AVISO) mesoscale eddy tracking dataset from satellite altimeter during the period from 1993 to 2017 was used to classify the mesoscale eddies in the East China Sea(ECS) according to the path. The results show that 318 cyclones and 276 anticyclones were detected in the ECS during the 25-year period. These mesoscale eddies were classified into the following types according to the path: (1) Eddy generated on the continental shelf of the ECS intrudes into deep sea(148 cases); (2) Eddy generated in deep sea intrudes into the continental shelf of the ECS(35 cases); (3) Eddy spreads along the isobath(180 cases); (4) Eddy wanders around(121 cases); (5) Eddy generated in Pacific Ocean intrudes into the shelf area of the ECS(25 cases) and (6) Eddy generated in Pacific Ocean intrudes into the ECS(85 cases). There existed very obvious seasonality for these six types. And the seasonal distribution for cyclones and anticyclones is diverse. The quantity of eddies for the type 3 is higher in spring and summer, lower in autumn and winter. The distribution of eddies for the type 1 is more evenly. The quantity of cyclones for the type 1 is the lowest in summer, and higher in spring and winter. The seasonal distribution for mesoscale eddies is related to the variations of the Kuroshio. The mean lifetime of eddies for type 4 is the longest, about 44 days. The mean amplitudes of eddies for type 1 and 5 are the largest, about 13.2 cm. The maximum mean diameter of the eddies is for type 5, about 122 km. The mean lifetime, amplitude and diameter of eddies for type 6 are the smallest.