南海贯穿流荷载中尺度过程能量学诊断  

ENERGY DIAGNOSTIC OF THE MESOSCALE PROCESSES LOADED BY THE SOUTH CHINA SEA THROUGHFLOW

作　　者：姚景龙[1] 李晗 刘钦燕[1] 王强[1] 肖福安 王东晓[1] 俎婷婷[1] 

机构地区：[1]中国科学院南海海洋研究所热带海洋环境国家重点实验室,广州510301 [2]广州大学地理科学学院,广州510006

出　　处：《海洋与湖沼》2017年第6期1257-1268,共12页Oceanologia Et Limnologia Sinica

基　　金：中国科学院战略性先导科技专项(A类)项目;XDA11010302号;XDA11010304号;XDA11010205号;国家自然科学基金项目;41576012号;41406038号;41406131号;41506022号

摘　　要：本文利用南海海洋再分析产品REDOS(Reanalysis Dataset of the South China Sea)和风场资料CCMP(Cross-Calibrated,Multi-Platform),通过能量诊断探讨了越南沿岸南海西边界流(南海贯穿流主体部分)区域夏季(6—9月)涡流相互作用的年际变化特征以及平均流对中尺度过程的贡献。结果显示,在季风和西边界强流、南海贯穿流的共同影响下,越南沿岸东向急流和双涡结构的能量分布和收支有显著的年际差异。尽管涡动能(EKE,Eddy Kinetic Energy)和涡动有效势能(EPE,Eddy available Potential Energy)的量级基本一致,但二者在水平和垂向空间分布上存在明显差异,这与夏季风影响下的南海西部边界流,越南离岸流的上层海洋密度梯度、流速大小和剪切导致的斜压、正压不稳定性等因素相关。同时随着深度的增加,密度梯度变化相对水平速度剪切对海洋涡流过程的影响逐渐凸显。EKE能量收支分析表明,压强与风应力主要做正功,是维持EKE稳定的主要能量来源,而EKE平流项既可以促进涡旋的增长,也会造成涡旋的消耗,对EKE的年际变率影响比较显著。正压不稳定导致的能量转换主要影响南海西部边界流区域,并存在显著年际变化,并且在风和平均流的影响下,沿贯穿流方向存在显著空间分布差异。越南离岸流正异常年,整体呈现平均流向涡旋传递能量;负异常年,出现EKE反哺平均动能的情况。The Reanalysis Dataset of the South China Sea（REDOS） and the wind data from CCMP（Cross-Calibrated, Multi-Platform） were used with energy diagnostic to study the interannual variation of eddy-mean flow interaction in the South China Sea（SCS） western boundary current（the main part of the South China Sea throughflow（SCSTF）） in summer from June to September. Results show that under the joint effects of monsoon wind, western boundary current, and SCSTF, the interannual variations of the mechanic energy distribution, the budget of the Vietnam eastward offshore jet, and the dipole structure are distinct. Although the Eddy Kinetic Energy（EKE） and Eddy available Potential Energy（EPE） are in the same order of magnitude, their spatial distributions are different obviously. This is related to the barotropic and baroclinic instability caused by the density gradient and horizontal velocity shear of the SCS western boundary current influenced by summer monsoon. Compared with the horizontal velocity shear, the impact of the density gradient on eddy–mean-flow interaction increases gradually with depth. The energy budget of EKE shows that pressure and wind stress do mainly a positive work to increase the EKE, while the advection term could either increase or dissipate the EKE, and it has a larger contribution to the interannual variation. The energy transfer caused by the barotropic instability affects mainly the region along the SCS western boundary current, and it has a distinct interannual variation with an obvious spatial difference along the SCSTF. In the positive anomaly years of the Vietnam offshore jet, the kinetic energy transfers from mean flow to eddy, while in the negative anomaly years, the transfer direction is opposite.

关 键 词：南海贯穿流 越南沿岸偶极子 能量诊断 涡-流相互作用 

分 类 号：P731[天文地球—海洋科学]