海洋涡旋在模态水形成与输运中的作用  

Mesoscale Eddy Effects on Subduction and Transport of the North Pacific Subtropical Mode Water

作　　者：许丽晓[1,2] 刘秦玉 XU Lixiao;LIU Qinyu(Frontier Science Center for Deep Ocean Multispheres and Earth System(FDOMES)and Physical Oceanography Laboratory,Ocean University of China,Qingdao 266100,China;Qingdao National Laboratory for Marine Science and Technology,Qingdao 266237,China)

机构地区：[1]中国海洋大学深海圈层与地球系统前沿科学中心&物理海洋教育部重点实验室,山东青岛266100 [2]青岛海洋科学与技术试点国家实验室,山东青岛266237

出　　处：《地球科学进展》2021年第9期883-898,共16页Advances in Earth Science

基　　金：国家自然科学基金面上项目“海洋涡旋在北太平洋副热带西部模态水输运中的作用”(编号:41876006)资助。

摘　　要：模态水在全球气候变化中有着重要作用。但是由于缺乏海洋次表层的高分辨率观测,对空间尺度为百公里的海洋中尺度涡旋如何影响空间尺度大于千公里的模态水的认识仍然欠缺。为了解决这一科学难题,在科技部的支持下,实施了一次成功的海上观测试验。系统梳理了基于该观测数据所发表的有关涡旋影响模态水潜沉和输运的主要研究成果:(1)捕捉并揭示了中尺度涡导致混合层水潜沉的过程和动力机制;(2)发现了中尺度涡携带模态水迁移的新路径;(3)阐明了模态水多核结构的形成机制。研究结果揭示了黑潮延伸体海域中尺度涡旋影响大尺度模态水的物理本质,为该海域多时空尺度海洋—大气相互作用作出了一定的贡献。通过对该次观测试验结果的分析和总结,得到了如下新的科学推论:海洋次中尺度过程对模态水的形成和耗散也具有重要影响。Mode Mode water is important for the climate system as memories of climate variability and by’breathing in’anthropogenic carbon dioxide.Due to the lack of subsurface observations,many fundamental questions remain regarding how it is subducted and transported by mesoscale eddies.Results from a field campaign from March 2014 that captured the eddy effects on mode water subduction and transport south of the Kuroshio Extension east of Japan are reviewed here.The experiment deployed 17 Argo floats in an Anticyclonic Eddy(AE)with enhanced daily sampling.Analysis of over 5000 hydrographic profiles following the eddy reveals that:(1)the eddy-induced North Pacific Subtropical Mode Water(STMW)subduction process is successfully captured for the first time,and the eddy subduction mechanism is revealed.We find potential vorticity and apparent oxygen utilization distributions are asymmetric outside the AE core,with enhanced subduction near the southeastern rim of the AE.There,the southward eddy flow advects newly ventilated mode water from the north into the main thermocline.Our results show that subduction by eddy lateral advection is comparable in magnitude to that by the mean flow—an effect that needs to be better represented in climate models.(2)A new mode water transport pathway by anticyclonic eddies is found.AEs transport STMW westward across the Izu Ridge through a bathymetric gap between the Hachijojima and Bonin Islands,forming a crossridge pathway for STMW transport.Because of the eddy transport,the shallow STMW(<400 m)intrudes through the gap westward,which is also observed in Argo climatology.(3)the formation mechanism of STMW multicore structure is clarified.We find that AEs formed east of 150°E could trap the local cold and dense STMW and migrate westward.Since sea surface temperatures increase toward the west,warmer and lighter STMWs are formed during the winter ventilation process as the AEs move westward.The newly formed STMW ride on the preexisting cold and dense STMW inside the eddy core,forming a mu

关 键 词：黑潮延伸体 海洋涡旋 模态水 潜沉与输运 多核结构 

分 类 号：P732.6[天文地球—海洋科学]