南海中尺度涡边缘亚中尺度过程模式研究
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摘要
基于高分辨率ROMS模式数据,对南海中尺度涡边缘的亚中尺度过程进行了研究。结果表明:在中尺度涡边缘处存在明显的温度细丝结构,涡度值要明显大于1,O~W参数趋于正值,即在涡旋边缘存在强速度剪切,加强了涡丝的形成。对亚中尺度过程动能空间分布分析发现,中尺度涡边缘区域动能所占的比例大约为88.4%,比中心区域动能所占的比例11.6%要大许多。从动能谱的分析来看,在中尺度涡边缘处动能谱的斜率趋近于k-2,与表层准地转理论(SQG)相吻合,而在中心处呈现k~(-3),与准地转理论(QG)相一致。
The study investigates thesubmesoscale process at a mesoscale eddy in South China Sea(SCS)based on high-resolution ROMS model.The results show that,at the periphery of themesoscale eddy,there exists obvious temperature filaments,the vorticity value is significantly greater than 1,and O-W parameter tends to be positive,all of these evidences meanthat the shear of velocity is much stronger and strengthen the formation of vortex filaments.From the view ofkinetic energy's distribution,for submesoscale process,the proportion at the periphery of the eddy(RR1and RR3)is 88.4%,which is larger than that at the center(RR2,only 11.6%).The results of kinetic energy spectra indicate that the slope of the spectra at the periphery of the eddy holds k~(-2) regime,which is more likely with surface quasi-geostrophic(SQG),while the slope exhibits k~(-3) law at the eddy's center,consistent with quasi-geostrophic(QG)theory.
The study investigates thesubmesoscale process at a mesoscale eddy in South China Sea(SCS)based on high-resolution ROMS model.The results show that,at the periphery of themesoscale eddy,there exists obvious temperature filaments,the vorticity value is significantly greater than 1,and O-W parameter tends to be positive,all of these evidences meanthat the shear of velocity is much stronger and strengthen the formation of vortex filaments.From the view ofkinetic energy's distribution,for submesoscale process,the proportion at the periphery of the eddy(RR1and RR3)is 88.4%,which is larger than that at the center(RR2,only 11.6%).The results of kinetic energy spectra indicate that the slope of the spectra at the periphery of the eddy holds k~(-2) regime,which is more likely with surface quasi-geostrophic(SQG),while the slope exhibits k~(-3) law at the eddy's center,consistent with quasi-geostrophic(QG)theory.
引文
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[2]Mahadevan A,Tandon A.An analysis of mechanisms for submesoscale vertical motion at ocean fronts[J].Ocean Modelling,2006,14(3):241-256.
[3]Capet X,McWilliams J C,Molemaker M J,et al.Mesoscale to submesoscale transition in the California Current System.Part I:Flow structure,eddy flux,and observational tests[J].Journal of Physical Oceanography,2008,38(1):29-43.
[4]Capet X,McWilliams J C,Molemaker M J,et al.Mesoscale to submesoscale transition in the California Current System.Part II:Frontal processes[J].Journal of Physical Oceanography,2008,38(1):44-64.
[5]Capet X,McWilliams J C,Molemaker M J,et al.Mesoscale to submesoscale transition in the California current system.Part III:Energy balance and flux[J].Journal of Physical Oceanography,2008,38(10):2256-2269.
[6]Gildor H,Fredj E,Steinbuck J,et al.Evidence for submesoscale barriers to horizontal mixing in the ocean from current measurements and aerial photographs[J].Journal of Physical Oceanography,2009,39(8):1975-1983.
[7]Klein P,Lapeyre G.The oceanic vertical pump induced by mesoscale and submesoscaleturbulence[J].Annual Review of Marine Science,2009,1:351-375.
[8]Zhong Y.Submesoscale dynamics and transport properties in the Gulf of Mexico[J].Georgia Insititute of Technology,2013:121-128.
[9]Lévy M,Iovino D,Resplandy L,et al.Large-scale impacts of submesoscale dynamics on phytoplankton:Local and remote effects[J].Ocean Modelling,2012,43:77-93.
[10]McGillicuddy D J,Anderson L A,Bates N R,et al.Eddy/wind interactions stimulate extraordinary mid-ocean plankton blooms[J].Science,2007,316(5827):1021-1026.
[11]Mason E,Molemaker J,Shchepetkin A F,et al.Procedures for offline grid nesting in regional ocean models[J].Ocean Modelling,2010,35(1):1-15.
[12]Umlauf L,Burchard H.A generic length-scale equation for geophysical turbulence models[J].Journal of Marine Research,2003,61(2):235-265.
[13]Orlanski I.A simple boundary condition for unbounded hyperbolic flows[J].Journal of Computational Physics,1976,21(3):251-269.
[14]Boccaletti G,Ferrari R,Fox-Kemper B.Mixed layer instabilities and restratification[J].Journal of Physical Oceanography,2007,37(9):2228-2250.
[15]Isern-Fontanet J,Font J,García-Ladona E,et al.Spatial structure of anticyclonic eddies in the Algerian basin(Mediterranean Sea)analyzed using the Okubo-Weiss parameter[J].Deep Sea Research Part II:Topical Studies in Oceanography,2004,51(25):3009-3028.
[16]Capet X,Campos E J,Paiva A M.Submesoscale activity over the Argentinian shelf[J].Geophysical Research Letters,2008,35(15):2015-2024.
[17]Wang D P,Flagg C N,Donohue K,et al.Wavenumber spectrum in the Gulf Stream from shipboard ADCP observations and comparison with altimetry measurements[J].Journal of Physical Oceanography,2010,40(4):840-844.
[18]Qiu B,Chen S,Klein P,et al.Seasonal mesoscale and submesoscale eddy variability along the North Pacific Subtropical Countercurrent[J].Journal of Physical Oceanography,2014,44(12):3079-3098.
[19]Callies J,Ferrari R.Interpreting energy and tracer spectra of upper-ocean turbulence in the submesoscale range(1-200km)[J].Journal of Physical Oceanography,2013,43(11):2456-2474.
[20]Callies J,Ferrari R,Klymak J M,et al.Seasonality in submesoscaleturbulence[J].Nature Communications,2015,6.
[21]Rocha C B,Chereskin T K,Gille S T,et al.Mesoscale to submesoscale wavenumber spectra in Drake Passage[J].Journal of Physical Oceanography,2015,46:601-620.