孟加拉湾海域背景流–中尺度涡–高频扰动之间的相互作用  

Multiscale interactions among the background flow,mesoscale eddy and high-frequency perturbation in the Bay of Bengal

作　　者：季页 杨洋 梁湘三 Ji Ye;Yang Yang;Liang Xiangsan(School of Marine Science,Nanjing University of Information Science and Technology,Nanjing 210044,China;College of Ocean and Earth Sciences,Xiamen University,Xiamen 361102,China;Department of Atmospheric and Oceanic Sciences,Fudan University,Shang-hai 200438,China;IRDR ICoE on Risk Interconnectivity and Governance on Weather/Climate Extremes Impact and Public Health,Fudan University,Shanghai 200438,China;Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai),Zhuhai 519000,China)

机构地区：[1]南京信息工程大学海洋科学学院,江苏南京210044 [2]厦门大学海洋与地球学院,福建厦门361102 [3]复旦大学大气与海洋科学系,上海200438 [4]复旦大学IRDR极端天气气候与健康风险互联和治理国际卓越中心,上海200438 [5]南方海洋科学与工程广东省实验室(珠海),广东珠海519000

出　　处：《海洋学报》2022年第9期23-37,共15页

基　　金：国家自然科学基金(41975064,41806023);2015江苏双创团队项目;上海市“科技创新行动计划”国际科技合作伙伴项目(21230780200)。

摘　　要：基于一套涡分辨模式数据,本文利用一种新的泛函工具—多尺度子空间变换—将孟加拉湾(BOB)海域的环流系统分解到背景流(>96 d)、中尺度(24~96 d)和高频尺度(<24 d)3个子空间,并用正则传输理论探讨了3个尺度子空间之间内在的非线性相互作用。结果表明,BOB西北部边界和斯里兰卡岛东部是BOB海域多尺度相互作用最显著的区域,中部则较弱。前两个区域的背景流大多正压、斜压不稳定,动能和有效位能正则传输主要表现为正向级串;后者则以逆尺度动能级串为主。具体来说,在BOB西北部与斯里兰卡东部,中尺度涡动能(EKE)主要来源于正压能量路径(即背景流动能向EKE传输),其次来源于斜压能量路径(即背景流有效位能向中尺度有效位能传输,并进一步转换为EKE)。通过这两个能量路径得到的EKE向更高频的扰动传输能量,起到了耗散中尺度涡的作用。不同于此二者,BOB中部海域的EKE和高频尺度动能主要通过斜压路径获得,随后通过逆尺度级串将动能返还给背景流。苏门答腊岛的西北部也是中尺度和高频尺度扰动较强的海域,正压能量路径和斜压能量路径均是该海域扰动能的来源,但以斜压能量路径为主。This study utilizes a new functional analysis tool,multiscale window transform(MWT),to decompose the ocean circulation system in the Bay of Bengal(BOB)into three scale windows,namely,the background flow window(>96 days),the mesoscale window(24–96 days)and the high-frequency window(<24 days),and then uses the canonical energy transfer theory to investigate the intrinsic nonlinear multiscale interactions among these windows,on the basis of an eddy-resolving model simulation.It is found that multiscale interactions are strongest along the northwestern boundary and east of Sri Lanka.With intense barotropic and baroclinic instabilities,the canonical transfers of kinetic energy(KE)and available potential energy(APE)are mainly forward in these two regions.Mesoscale eddy kinetic energy(EKE)reservoir is mainly filled by the barotropic energy pathway with the kinetic energy of the background flow transferring to EKE,and secondarily from the baroclinic energy pathway with APE of the background flow transferring to the mesoscale APE and further converting to EKE.The gained EKE is found to further cascade to high-frequency motions,acting as an important dissipation mechanism of the mesoscale eddies in these regions.In contrast,the central BOB is mainly characterized by inverse KE cascades,where EKE and high-frequency kinetic energy(HKE)are gained via the baroclinic energy pathway,and then feed the background flow through inverse cascade processes.The northwest of Sumatra is also an area with strong mesoscale and high-frequency variability.Both barotropic and baroclinic energy pathways are the sources for EKE and HKE reservoirs in this region,with the baroclinic energy pathway playing the dominant role.

关 键 词：孟加拉湾 多尺度子空间变换 正则传输 多尺度相互作用 正压不稳定 斜压不稳定 

分 类 号：P732.6[天文地球—海洋科学]