摘要
中尺度涡在南海活动频繁,尤其是持续时间长的强中尺度涡对海区内多尺度环流系统的能量输送和物质搬运具有重要调控作用。利用AVISO卫星高度计资料和最外层闭合等值线法,对2011-2018年南海北部的中尺度涡进行识别和追踪,重点讨论中尺度涡在最近几年的时空分布变化。统计结果显示,南海北部平均每年生成8.6个反气旋涡和4.5个气旋涡(持续时间大于28天),其中近1/3为强中尺度涡(持续时间大于45天),表现出较强的涡动能和非线性等动力特征,基本与前人统计的其他年份结果一致。南海北部中尺度涡的生成地点、传播路径以及活动频率分布具有显著的季节变化特征。对比发现,反气旋涡在秋季和冬季主要形成于吕宋海峡北侧,沿等深线向西南移动,最高活动频率超过30%;夏季主要在菲律宾吕宋岛西侧形成,平行于纬线向西移动。而气旋涡在冬季和春季主要形成于吕宋海峡西侧,向西南移动,最高活动频率约为26%。另外,台湾岛西南岸外易生成强中尺度涡涡对,综合黑潮指数进一步分析发现,黑潮入侵南海形成流套是促使该强涡对生成的主要机制。
Mesoscale eddies are active and energetic in the South China Sea(SCS),and play an important role in regulating the multi-scale circulation and mass transportation in the region,especially for those long-lived strong eddies. Using AVISO altimeter data and outermost closed contour sea level anomaly method,this study identified and tracked mesoscale eddies in the northern SCS during 2011-2018,and focused on the temporal and spatial characteristics of mesoscale eddies in recent years. Similarly to previous results in this region,statistical results show that about 8.6 anticyclonic eddies and 4.5 cyclonic eddies(lifetime > 28 days)were born per year.Among them,about 1/3 of the total number are strong eddies(lifetime > 45 days),showing relatively strong dynamic characteristics,such as strong Eddy Kinetic Energy(EKE)and highly nonlinear feature. Statistics also show significant seasonal variability in mesoscale eddies’ birth places,trajectories and distribution of frequency of occurrence. Specifically,anticyclonic eddies mainly form at the north part of Luzon Strait between autumn and winter,and then move southwestward along isobaths. During this period,the largest value of the frequency of occurrence is over 30%. In summer,most of them form in the west off Luzon Island,and then move westward paralleling to latitude lines. In contrast,cyclonic mainly form in the west off Luzon Strait,and then move westward in winter and spring. During this period,the largest value is about 26%. In addition,observation finds that the strong mesoscale eddy pair could generate off the southwest of Taiwan Island. Analysis of the Kuroshio SCS Index(KSI) implies that loop current caused by Kuroshio intrusion is the most important mechanism for the formation of eddy pair.
作者
王萌
张艳伟
刘志飞
吴家望
Wang Meng;Zhang Yanwei;Liu Zhifei;Wu Jiawang(State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China)
出处
《地球科学进展》
CAS
CSCD
北大核心
2019年第10期1069-1080,共12页
Advances in Earth Science
基金
国家自然科学基金面上项目“中尺度涡对南海东北部深层湍流混合的影响”(编号:41576005)
国家自然科学基金重点项目“南海中央海盆中新世以来深水沉积作用及其区域构造与环境演化意义”(编号:41530964)资助~~
关键词
中尺度涡
卫星高度计
时空统计
黑潮
南海北部
Mesoscale eddies
Altimeter data
Statistics
Kuroshio
Northern South China Sea
