中美洲鹦鹉湾气旋涡的亚中尺度结构特征  

Submesoscale features of a cyclonic eddy in the Gulf of Papagayo,Central America

作　　者：杨顺 宋海斌[1] 范文豪 吴迪 YANG Shun;SONG HaiBin;FAN WenHao;WU Di(State Key Laboratory of Marine Geology,School of Ocean and Earth Science,Tongji University,Shanghai 200092,China)

机构地区：[1]海洋地质国家重点实验室,同济大学海洋与地球科学学院,上海200092

出　　处：《地球物理学报》2021年第4期1328-1340,共13页Chinese Journal of Geophysics

基　　金：国家自然科学基金(41976048);全球变化专项国际合作项目“东亚大陆边缘现代地质过程与致灾机理”(GASI-GEOGE-05);国家重点研发计划(2018YFC0310000)资助.

摘　　要：海洋中普遍存在的涡旋对全球海洋热、盐通量有重要贡献.一条于2000年6月在中美洲鹦鹉湾采集的地震剖面L115捕获到了一个海水次表层透镜状反射结构.透镜状反射的宽度约150 km,厚度约500 m,深度从100 m延伸到约600 m,核心深约200 m.结合和地震采集时间近同步的再分析数据中的流速和海水温度数据以及计算的Rossby数和Okubo-Weiss参数,将其解释为气旋涡,且可能是亚中尺度相干涡(SCV).由于地震剖面并未穿过涡旋核心水,涡旋顶底与核心水外层水团的双扩散作用使得剖面上的气旋涡中心表现为上下相邻的强反射双核结构.同航次采集的与L115大致正交的其他几条地震剖面也捕捉到了这个气旋涡.这些剖面整体的反射特征一致性较好,但和L115差异较大,涡旋内部普遍表现为近水平的中等强度反射.涡旋上边界为倾斜的强反射,这是气旋涡的等温线上凸引起的,这里也是亚中尺度锋面的发育区.这些地震剖面的涡旋反射特征的差异表明了该气旋涡空间结构的不对称性和时间演化特征.The eddies are ubiquitous in the ocean and play an important role in the transporting and redistributing heat,salt,CO 2,nutrients or other materials to the global ocean′s interior.Here,a subsurface lens-shaped reflection structure of sea water is captured by L115,a seismic transect that was acquired in the Gulf of Papagayo,Central America in June 2000.The lens-shaped reflection has a width of~150 km,a thickness of~500 m,a depth range of 100 m to~600 m,and the center depth of~200 m.Rossby number and Okubo-Weiss parameter calculated by the re-analysis data of sea water velocity,and temperature infer the lens-shaped reflection as a cyclonic eddy.Our results show that the lens-shaped refletion may be a submesoscale coherent vortex(SCV).Different from the general eddies with weak reflection characteristics in the core,the cyclonic eddy in our study has a dual-core strong reflection structure adjacent to the top and bottom.Because the seismic transect does not pass through the core water of the eddy,the strong reflection of the core may be caused by the double diffusion between the top and bottom of the eddy and the outer water masses.The cyclonic eddy is also captured by 7 other seismic transects roughly orthogonal to L115.The reflection characteristics of these transects are consistent with each other,but different from L115.The interior of the eddy generally shows a near horizontal medium intensity reflection.In addition,the upper boundary of the eddy is strong oblique reflection,which is due to the convexity of the isotherm of the cyclonic eddy,and here is also the submesoscale frontal zone.The difference of the eddy reflection characteristics of the eight transects indicates the asymmetry of the spatial structures and the evolution characteristics of the cyclonic eddy.

关 键 词：气旋涡 反射结构 亚中尺度 地震海洋学 中美洲 

分 类 号：P738[天文地球—海洋地质]