Mesoscale eddies contribute to the global oceanic energy budget and cascade;they induce substantial mass and heat transport,thus playing a key role in the global climate system.The three-dimensional(3D)structures of mesoscale eddies should be studied in order to quantify their impact.In this paper,mesoscale eddies are reviewed from the perspective of their horizontal and vertical structures,temporal evolution,and fine structures.The universal 3D structure of mesoscale eddies is revealed via observations,and findings show that their tendency to achieve lowest-energy or minimum-dissipation states shapes their lowest-order coherent structure.Recent efforts also push forward to the higher-order structure of eddies:The understanding of horizontal structures is gradually evolving from symmetric to asymmetric,and the vertical structure based on separable variable assumption and vertical mode decomposition should further take the eddy vertical alignment and tilt into account.The temporal evolution of mesoscale eddies’3D structure is in a dynamical balance influenced by multiple competitive factors,such as eddies’self-sustaining ability,background gradient and deformation,and generation of submesoscale fine structures.The submesoscale processes associated with mesoscale eddies have been intensively studied in recent years,and they should be considered as a fine-scale part of the 3D structure of eddies rather than separate instability processes.This review hopes to provide the readers with an enlightening,yet not thorough,review of the development of mesoscale eddies’structures and brings up potential topics and unresolved difficulties for further research and development.
Mid-ocean ridge and oceanic transforms are among the most prominent features on the seafloor surface and are crucial for understanding seafloor spreading and plate tectonic dynamics,but the deep structure of the oceanic lithosphere remains poorly understood.The large number of microearthquakes occurring along ridges and transforms provide valuable information for gaining an indepth view of the underlying detailed seismic structures,contributing to understanding geodynamic processes within the oceanic lithosphere.Previous studies have indicated that the maximum depth of microseismicity is controlled by the 600-℃isotherm.However,this perspective is being challenged due to increasing observations of deep earthquakes that far exceed this suggested isotherm along mid-ocean ridges and oceanic transform faults.Several mechanisms have been proposed to explain these deep events,and we suggest that local geodynamic processes(e.g.,magma supply,mylonite shear zone,longlived faults,hydrothermal vents,etc.)likely play a more important role than previously thought.
大洋性鱿鱼是海洋中重要的经济类群,在海洋生态系统中扮演着重要的角色。通过Web of Science核心合集获取的文献数据,利用文献计量学与CiteSpace软件的共现分析、聚类分析与突变检测等分析方法,对该主题1991—2021年的年度发文量分布、作者及研究机构组成与合作、研究主题演变及热点展示等方面进行了分析。结果显示,研究文献的年度分布总体呈现动态递增趋势;主要作者间合作密切,形成分别以中国上海海洋大学CHEN X J(陈新军)等、美国缅因大学CHEN Y(陈勇)等、西班牙海洋研究所PIERCE G J等以及葡萄牙生物资源研究所PEREIRA J等为核心的4个合作关系密切的作者群,并形成稳定的合作关系;主要研究机构中,英国南极调查局、法国海洋开发研究院、美国国家海洋和大气管理局、阿伯丁大学、西班牙海洋研究所、戴尔豪斯大学等机构的国际合作能力较强;主要研究国家或地区方面,美国、德国、日本、中国内地、英格兰等为该主题的主要研究力量。当前该主题的研究热点共分为5个方面:1)气候变化对大洋性鱿鱼资源种群动态的影响;2)基于生态系统的鱿鱼渔业管理策略研究;3)气候变化对大洋性鱿鱼的生活史影响;4)气候变化对大洋性鱿鱼栖息地影响;5)气候变化对大洋性鱿鱼海洋环境适应性及其生物多样性的影响。
In 2018 and 2021,the Drift-Towing Ocean Profilers(DTOP)provided extensive temperature and salinity data on the upper 120m ocean through their drifts over the Alpha Ridge north of the Canada Basin.The thickness and temperature maximum of Alaska Coastal Water(ACW)ranged from 20m to 40m and-1.5℃to-0.8℃,respectively,and the salinity generally maintained from 30.2 to 32.5.Comparison with World Ocean Atlas 2018’s climatology manifested a 40m-thick and warm ACW roughly ex-ceeding the temperature maximum by 0.4–0.5℃in June–August 2021.This anomalously warm ACW was highly related to the ex-pansion of the Beaufort Gyre in the negative Arctic Oscillation phase.During summer,the under-ice oceanic heat flux F_(w)^(OHF)was elevated,with a maximum value of above 25Wm^(-2).F_(w)^(OHF)was typically low in the freezing season,with an average value of 1.2Wm^(-2).The estimates of upward heat flux contributed by ACW to the sea ice bottom F_(w)^(OHF)were in the range of 3–4Wm^(-2)in June–August 2021,when ACW contained a heat content of more than 80MJm^(-2).The heat loss over this period was driven by a weak stratification upon the ACW layer associated with a surface mixed layer(SML)approaching the ACW core.After autumn,F_(w)^(OHF)was reduced(<2 Wm^(-2))except during rare events when it elevated F_(w)^(OHF)slightly.In addition,the intensive and widespread Ekman suction,which created a violent upwelling north of the Canada Basin,was largely responsible for the substantial cooling and thinning of the ACW layer in the summer of 2021.
本文利用天气研究和预报(Weather research and forecasting,WRF)模式设置了两组具有不同海洋锋面强度的“渠道模型”理想数值试验,忽略地形作用,探讨了冬季海洋锋面对大气河(Atmospheric river,AR)的影响。结果表明,在不同强度的海洋锋面试验中,大气低层风速、湍流热通量等物理量的响应与海温的变化同位相,且大气低层各变量对海洋锋面南侧海温变化的响应较北侧更大,呈现出南北不对称性。海洋锋强度的增强促进了向高空的涡动热量和水汽输送,导致高空风速加强和风暴轴北移。海洋锋面的增强还为经过其上空的气旋提供了更多的动量和水汽,加强了气旋南侧的水汽输送带,从而促进了大气河发生频数的增加和大气河强度的增强。
