<noframes id="dzdnh">

<form id="dzdnh"></form><noframes id="dzdnh"><address id="dzdnh"><nobr id="dzdnh"></nobr></address>
<form id="dzdnh"><nobr id="dzdnh"></nobr></form>
    <noframes id="dzdnh">
      Quick Search:       Advanced Search
    Huang Xiaolong,Jing Zhiyou,Zheng Ruixi,Cao Haijin. 2020. Dynamical analysis of submesoscale fronts associated with wind-forced offshore jet in the western South China Sea. Acta Oceanologica Sinica, 39(11):1-12
    Dynamical analysis of submesoscale fronts associated with wind-forced offshore jet in the western South China Sea
    南海西部風驅離岸急流次中尺度鋒面的動力學分析
    Received:April 13, 2020  
    DOI:10.1007/s13131-020-1671-4
    Key words:submesoscale fronts  enhanced vertical velocity  energy transfer  offshore jet  western South China Sea
    中文關鍵詞:  次中尺度鋒面  增強的垂直速度  能量傳遞  離岸急流  南海西部
    基金項目:This work is supported by the Chinese Academy of Sciences under contract Nos ZDBS-LY-DQC011, ZDRW-XH-2019-2 and ISEE2018PY05; the Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou) under contract No. GML2019ZD0303; the National Natural Science Foundation of China under contract Nos 41776040 and 92058201; the Pilot National Laboratory for Marine Science and Technology (Qingdao) under contract No. OCFL-201804; the State Key Laboratory of Tropical Oceanography under contract No. LTO1907; the Guangzhou Science and Technology Project under contract No. 201904010420.
    Author NameAffiliationE-mail
    Huang Xiaolong State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
    University of Chinese Academy of Sciences, Beijing 100049, China 
     
    Jing Zhiyou State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
    Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou 511458, China
    Innovation Academy of South China Sea Ecology and Environmental Engineering, Chinese Academy of Sciences, Guangzhou 510301, China 
    jingzhiyou@scsio.ac.cn 
    Zheng Ruixi State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
    University of Chinese Academy of Sciences, Beijing 100049, China 
     
    Cao Haijin College of Oceanography, Hohai University, Nanjing 210024, China  
    Hits: 1151
    Download times: 3925
    Abstract:
          This study investigates the submesoscale fronts and their dynamic effects on the mean flow due to frontal instabilities in the wind-driven summer offshore jet of the western South China Sea (WSCS), using satellite observations, a 500 m-resolution numerical simulation, and diagnostic analysis. Both satellite measurements and simulation results show that the submesoscale fronts occupying a typical lateral scale of O(~10) km are characterized with one order of Rossby (Ro) and Richardson (Ri) numbers in the WSCS. This result implies that both geostrophic and ageostrophic motions feature in these submesoscale fronts. The diagnostic results indicate that a net cross-frontal Ekman transport driven by down-front wind forcing effectively advects cold water over warm water. By this way, the weakened local stratification and strong lateral buoyancy gradients are conducive to a negative Ertel potential vorticity (PV) and triggering frontal symmetric instability (SI) at the submesoscale density front. The cross-front ageostrophic secondary circulation caused by frontal instabilities is found to drive an enhanced vertical velocity reaching O(100) m/d. Additionally, the estimate of the down-front wind forcing the Ekman buoyancy flux (EBF) is found to be scaled with the geostrophic shear production (GSP) and buoyancy flux (BFLUX), which are the two primary energy sources for submesoscale turbulence. The large values of GSP and BFLUX at the fronts suggest an efficient downscale energy transfer from larger-scale geostrophic flows to the submesoscale turbulence owing to down-front wind forcing and frontal instabilities. In this content, submesoscale fronts and their instabilities substantially enhance the local vertical exchanges and geostrophic energy cascade towards smaller-scale. These active submesoscale processes associated density fronts and filaments likely provide new physical interpretations for the filamentary high chlorophyll concentration and frontal downscale energy transfer in the WSCS.
    中文摘要:
          本文利用衛星觀測資料和500 m分辨率數值模擬結果,結合理論分析,對南海西部夏季風場驅動的離岸急流海域次中尺度鋒面及其不穩定對背景流場的動力學影響進行了研究。衛星觀測和模擬結果表明,南海西部(WSCS)存在側向尺度為O(1-10)km的次中尺度鋒面,在地轉和非地轉運動的共同作用下,次中尺度密度鋒面具有一階Rossby(Ro)和Richardson(Ri)數。鋒面診斷結果顯示,沿鋒面急流方向的風場強迫引起了顯著的跨鋒面Ekman凈輸送,有效地在跨鋒面方向將表層冷水平流輸送至暖水側,導致海表浮力損失。減弱的垂向層結和增強的水平浮力梯度使得鋒面海域出現負Ertel位渦(PV),表明該密度鋒面易受次中尺度對稱不穩定(SI)的影響。次中尺度鋒面不穩定引起的跨鋒面次級環流能夠顯著增強垂向速度,其最大值可達100 m·d-1。能量評估結果表明,次中尺度湍流的兩個主要能量源,即地轉剪切項(GSP)和垂向浮力通量(BFLUX)在鋒面海域顯著增強表明在沿鋒面急流方向的風場強迫作用下,大尺度地轉流的地轉剪切動能和鋒面有效位能能有效地通過鋒面不穩定向次中尺度過程傳遞。因此,次中尺度鋒面及其不穩定有助于增強局地垂向交換和正向串級地轉能量,可以為夏季WSCS高葉綠素濃度的相干結構和鋒面地轉能量的正向傳遞提供新的動力解釋。
    HTML View Full Text   View/Add Comment  Download reader
    Close
    乱中年女人伦av三区