日本海中尺度涡旋时空变化特征研究

Spatiotemporal variations of mesoscale eddies in the Japan Sea

本文利用1993–2019年基于海表面高度异常的涡旋数据集和高度计数据统计分析了日本海区域中尺度涡旋的大小、极性、生命周期、振幅、传播等表面特征的时空变化规律。27年间,共探测到1429个涡旋,气旋和反气旋数量基本相当,其中气旋675个,反气旋754个。两种极性涡旋均具有较强的季节变化:秋季较多,冬季次之,春季最少。郁陵盆地、大和盆地等为涡旋多发区域呈现西南–东北向带状分布。其中,南部海域反气旋占优,靠近津轻海峡的北部海域气旋占优。西部和南部受东韩暖流和对马暖流的驱动,涡旋移动方向与流场基本一致,北部涡旋与黎曼寒流以及副极地锋流有关。研究表明,动力学不稳定是涡旋在秋冬季大量产生的重要原因。此外,半封闭盆地、局地流场以及复杂的海气相互作用等都可能会对涡旋的产生和消亡造成一定影响。

In this paper,surface characteristics of mesoscale eddies in the Japan Sea(JES),including size,polarity,life cycle,amplitude,and trajectory,are analyzed by using eddy datasets and sea level anomaly altimeter data from 1993 to 2019.Over the 27-year period,a total of 1429 eddies were detected with nearly equal number of cyclonic and anticyclonic eddies(CEs and AEs,respectively).Strong seasonal variability was observed for both polarities of eddy.The eddies were most generated in autumn,followed by winter and the least in the spring.Mesoscale eddies are prone to generate in the Ulleung Basin and Yamato Basin,which distributed in a southwest-northeast zonal belt.Among them,ACs are dominant in the southern JES,while CEs in the northern JES near the Tsugaru Strait.The western and southern movements of the mesoscale eddies were driven by the East Korean Warm Current and Tsushima Warm Current.In the northern JES,the mesoscale eddies were more related to the Liman cold current and subpolar front current.Further studies shown that dynamical instability is an important reason for the generation of eddies in autumn and winter.However,semi-enclosed basins,local flow fields,and complex air-sea interactions may all have a certain impact on the generation and dissipation of the mesoscale eddies.