黑潮延伸体区域脱落涡旋的时空特征分析

Temporal and spatial characteristics of pinch-off rings in the Kuroshio Extension region

本文利用1993-2015年AVISO卫星高度计融合数据,统计分析了从黑潮延伸体流轴脱落涡旋的空间分布特征、运动属性以及季节、年际和类年代际变化。研究结果表明,23年间共追踪到242个气旋涡,276个反气旋涡,脱落的涡旋主要分布在沙茨基海隆以西区域。从脱落涡旋的源地空间分布来看,气旋涡的形成区域有两个高值区,一个位于黑潮延伸体流轴稳定弯曲处,即144°～146°E之间的上游区域;另一个位于沙茨基海隆西侧156°E处。而反气旋涡的形成区域也有两个高值区,一个位于沙茨基海隆以西的下游区域,另一个位于148°E处。这些在上游和下游脱落的涡旋大多向西移动,其中有88%的涡旋再次被流轴吸收。脱落涡旋的数量显示出了明显的年际和类年代际变化。在流轴的上下游区域,类年代际和年际变化分别占主导地位。并且在上游区域,脱落涡旋的类年代际变化与黑潮延伸体的强度呈负相关。在季节变化上,夏季脱落形成的涡旋最多,冬季最少。

This study examined the spatial distribution characteristics,motion properties,seasonal,interannual and decadal variations of oceanic rings shed from the Kuroshio Extension(KE)jet using AVISO satellite altimeter observations from January 1993 to December 2015.The results show that 242 cyclones and 276 anticyclones are detected in the past 23 years,and pinch-off rings mostly distribute in the region west of the Shatsky Rise.According to the spatial distribution of the ring formations in the KE region,there are two high value regions of cyclonic rings.One is located at the upstream region between 144°-146°E around the steady meander of the KE jet,the other is located at 156°E west of the Shatsky Ridge.There are two high value regions of anticyclonic rings,one located at downstream region west of the Shatsky Ridge and the other located at 148°E.These pinched-off rings in both the upstream and downstream regions generally propagated westward,but about 88%of the rings are reabsorbed by the jet.The number of ring formations show substantial interannual to decadal-like variability.In the upstream and downstream KE region,decadal-like and interannual variability is dominant,respectively.In the upstream region,these fluctuations of the ring formations are negatively correlated with the strength of the KE jet.In terms of seasonal variation,the most rings formed in summer,and the least in winter.