南海贯穿流荷载中尺度过程能量学诊断
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摘要
本文利用南海海洋再分析产品REDOS(Reanalysis Dataset of the South China Sea)和风场资料CCMP(Cross-Calibrated,Multi-Platform),通过能量诊断探讨了越南沿岸南海西边界流(南海贯穿流主体部分)区域夏季(6—9月)涡流相互作用的年际变化特征以及平均流对中尺度过程的贡献。结果显示,在季风和西边界强流、南海贯穿流的共同影响下,越南沿岸东向急流和双涡结构的能量分布和收支有显著的年际差异。尽管涡动能(EKE,Eddy Kinetic Energy)和涡动有效势能(EPE,Eddy available Potential Energy)的量级基本一致,但二者在水平和垂向空间分布上存在明显差异,这与夏季风影响下的南海西部边界流,越南离岸流的上层海洋密度梯度、流速大小和剪切导致的斜压、正压不稳定性等因素相关。同时随着深度的增加,密度梯度变化相对水平速度剪切对海洋涡流过程的影响逐渐凸显。EKE能量收支分析表明,压强与风应力主要做正功,是维持EKE稳定的主要能量来源,而EKE平流项既可以促进涡旋的增长,也会造成涡旋的消耗,对EKE的年际变率影响比较显著。正压不稳定导致的能量转换主要影响南海西部边界流区域,并存在显著年际变化,并且在风和平均流的影响下,沿贯穿流方向存在显著空间分布差异。越南离岸流正异常年,整体呈现平均流向涡旋传递能量;负异常年,出现EKE反哺平均动能的情况。
The Reanalysis Dataset of the South China Sea(REDOS) and the wind data from CCMP(Cross-Calibrated, Multi-Platform) were used with energy diagnostic to study the interannual variation of eddy-mean flow interaction in the South China Sea(SCS) western boundary current(the main part of the South China Sea throughflow(SCSTF)) in summer from June to September. Results show that under the joint effects of monsoon wind, western boundary current, and SCSTF, the interannual variations of the mechanic energy distribution, the budget of the Vietnam eastward offshore jet, and the dipole structure are distinct. Although the Eddy Kinetic Energy(EKE) and Eddy available Potential Energy(EPE) are in the same order of magnitude, their spatial distributions are different obviously. This is related to the barotropic and baroclinic instability caused by the density gradient and horizontal velocity shear of the SCS western boundary current influenced by summer monsoon. Compared with the horizontal velocity shear, the impact of the density gradient on eddy–mean-flow interaction increases gradually with depth. The energy budget of EKE shows that pressure and wind stress do mainly a positive work to increase the EKE, while the advection term could either increase or dissipate the EKE, and it has a larger contribution to the interannual variation. The energy transfer caused by the barotropic instability affects mainly the region along the SCS western boundary current, and it has a distinct interannual variation with an obvious spatial difference along the SCSTF. In the positive anomaly years of the Vietnam offshore jet, the kinetic energy transfers from mean flow to eddy, while in the negative anomaly years, the transfer direction is opposite.
The Reanalysis Dataset of the South China Sea(REDOS) and the wind data from CCMP(Cross-Calibrated, Multi-Platform) were used with energy diagnostic to study the interannual variation of eddy-mean flow interaction in the South China Sea(SCS) western boundary current(the main part of the South China Sea throughflow(SCSTF)) in summer from June to September. Results show that under the joint effects of monsoon wind, western boundary current, and SCSTF, the interannual variations of the mechanic energy distribution, the budget of the Vietnam eastward offshore jet, and the dipole structure are distinct. Although the Eddy Kinetic Energy(EKE) and Eddy available Potential Energy(EPE) are in the same order of magnitude, their spatial distributions are different obviously. This is related to the barotropic and baroclinic instability caused by the density gradient and horizontal velocity shear of the SCS western boundary current influenced by summer monsoon. Compared with the horizontal velocity shear, the impact of the density gradient on eddy–mean-flow interaction increases gradually with depth. The energy budget of EKE shows that pressure and wind stress do mainly a positive work to increase the EKE, while the advection term could either increase or dissipate the EKE, and it has a larger contribution to the interannual variation. The energy transfer caused by the barotropic instability affects mainly the region along the SCS western boundary current, and it has a distinct interannual variation with an obvious spatial difference along the SCSTF. In the positive anomaly years of the Vietnam offshore jet, the kinetic energy transfers from mean flow to eddy, while in the negative anomaly years, the transfer direction is opposite.
引文
方文东,方国洪,1998.南海南部海洋环流研究的新进展.地球科学进展,13(2):166-172
王东晓,刘钦燕,谢强等,2013.与南海西边界流有关的区域海洋学进展.科学通报,58(14):1277-1288
王东晓,周发璓,秦曾灏,1996.南海上层海洋环流两层半模式的数值模拟Ⅰ.闭边界海盆季节性环流.海洋学报,18(5):30-40
李晗,王强,黄科等,2017.1992-2011年夏季南海西部离岸流区涡流相互作用特征.海洋与湖沼,48(5):912-925
曾庆存,李荣凤,季仲贞等,1989.南海月平均流的计算.大气科学,13(2):127-138
Atlas R,Hoffman R N,Ardizzone J et al,2011.Across-calibrated,multiplatform ocean surface wind velocity product for meteorological and oceanographic applications.Bulletin of the American Meteorological Society,92:157-174
Beckmann A,B?ning C W,Brügge B et al,1994.On the generation and role of eddy variability in the central North Atlantic Ocean.Journal of Geophysical Research:Oceans,99(C10):20381-20391
B?ning C W,Budich R G,1992.Eddy dynamics in a primitive equation model:Sensitivity to horizontal resolution and friction.Journal of Physical Oceanography,22(4):361-381
Cai S Q,Long X M,Wang S G,2007.A model study of the summer Southeast Vietnam Offshore Current in the southern South China Sea.Continental Shelf Research,27(18):2357-2372
Chen C L,Wang G H,2014.Interannual variability of the eastward current in the western South China Sea associated with the summer Asian monsoon.Journal of Geophysical Research:Oceans,119(9):5745-5754
Cheng X H,Qi Y Q,2010.Variations of eddy kinetic energy in the South China Sea.Journal of Oceanography,66(1):85-94
Fang G,Wang G,Fang Y et al,2012.A review on the South China Sea western boundary current.Acta Oceanologica Sinica,31(5):1-10
Fang W D,Fang G H,Shi P et al,2002.Seasonal structures of upper layer circulation in the southern South China Sea from in situ observations.Journal of Geophysical Research:Oceans,107(C11):23-1-23-12
Gan J P,Qu T D,2008.Coastal jet separation and associated flow variability in the southwest South China Sea.Deep Sea Research Part I:Oceanographic Research Papers,55(1):1-19
Geng W,Xie Q,Chen G X et al,2016.Numerical study on the eddy-mean flow interaction between a cyclonic eddy and Kuroshio.Journal of Oceanography,2016,72(5):727-745
Gill A E,2016.Atmosphere-Ocean Dynamics.Amsterdam:Elsevier
Hu J Y,Gan J P,Sun Z Y et al,2011.Observed three-dimensional structure of a cold eddy in the southwestern South China Sea.Journal of Geophysical Research:Oceans,116(C5):C05016
Ivchenko V O,Tréguier A M,Best S E,1997.A kinetic energy budget and internal instabilities in the Fine Resolution Antarctic Model.Journal of Physical Oceanography,27(1):5-22
Jia Y L,Liu Q Y,Liu W,2005.Primary study of the mechanism of eddy shedding from the Kuroshio bend in Luzon Strait.Journal of Oceanography,61(6):1017-1027
Kang D J,Curchitser E N,2015.Energetics of eddy-mean flow interactions in the Gulf Stream region.Journal of Physical Oceanography,45(4):1103-1120
Kuo Y C,Chern C S,2011.Numerical study on the interactions between a mesoscale eddy and a western boundary current.Journal of Oceanography,67(3):263-272
Li L,Xu J D,Jing C S et al,2003.Annual variation of sea surface height,dynamic topography and circulation in the South China Sea-A TOPEX/Poseidon satellite altimetry study.Science in China Series D:Earth Sciences,46(2):127-138
Li Y L,Han W Q,Wilkin J L et al,2014.Interannual variability of the surface summertime eastward jet in the South China Sea.Journal of Geophysical Research:Oceans,119(10):7205-7228
Liu Z Y,Yang H J,Liu Q Y,2001.Regional dynamics of seasonal variability in the South China Sea.Journal of Physical Oceanography,31(1):272-284
Lorenz E N,1955.Available potential energy and the maintenance of the general circulation.Tellus,7(2):157-167
Nan F,He Z G,Zhou H et al,2011.Three long-lived anticyclonic eddies in the northern South China Sea.Journal of Geophysical Research,116(C5):C05002,http://dx.doi.org/10.1029/2010JC006790
Qu T D,Du Y,Sasaki H,2006.South China Sea throughflow:Aheat and freshwater conveyor.Geophysical Research Letters,33:L23617,doi:10.1029/2006GL028350
Quan Q,Xue H J,Qin H L et al,2016.Features and variability of the South China Sea western boundary current from 1992 to2011.Ocean Dynamics,66(6-7):795-810
Shang X D,Liu Q,Xie X H et al,2015.Characteristics and seasonal variability of internal tides in the southern South China Sea.Deep Sea Research Part I:Oceanographic Research Papers,98:43-52
Shaw P T,Chao S Y,Fu L L,1999.Sea surface height variations in the South China Sea from satellite altimetry.Oceanologica Acta,22(1):1-17
Treguier A M,1992.Kinetic energy analysis of an eddy resolving,primitive equation model of the North Atlantic.Journal of Geophysical Research:Atmospheres,97:687-701
Von Storch J S,Eden C,Fast I et al,2012.An estimate of the Lorenz energy cycle for the world ocean based on the STORM/NCEP simulation.Journal of Physical Oceanography,42(12):2185-2205
Wang D X,Liu Q Y,Huang R X et al,2006.Interannual variability of the South China Sea throughflow inferred from wind data and an ocean data assimilation product.Geophysical Research Letters,33:L14605,doi:10.1029/2006GL026316
Wang D X,Xu H Z,Lin J et al,2008.Anticyclonic eddies in the northeastern South China Sea during winter 2003/2004.Journal of Oceanography,64(6):925-935
Wang G H,Su J L,Chu P C,2003.Mesoscale eddies in the South China Sea observed with altimeter data.Geophysical Research Letters,30(21):2121
Wang G H,Wang C Z,Huang R X,2010.Interdecadal variability of the eastward current in the South China Sea associated with the summer Asian monsoon.Journal of Climate,23(22):6115-6123
Wu C R,Shaw P T,Chao S Y,1999.Assimilating altimetric data into a South China Sea model.Journal of Geophysical Research:Oceans,1042(C12):29987-30005
Xiang R,Fang W D,Zhou S Q,2016.The anticyclonic circulation in the southern South China Sea:Observed structure,seasonal development and interannual variability.Journal of Marine Systems,154:131-145
Xiu P,Chai F,Shi L et al,2010.A census of eddy activities in the South China Sea during 1993-2007.Journal of Geophysical Research:Oceans,115(C3):C03012
Xue H,Mellor G L,1993.Instability of the Gulf Stream front in the South Atlantic Bight.Journal of Physical Oceanography,23:2326-2350
Yang H J,Liu Q Y,Liu Z Y et al,2002.A general circulation model study of the dynamics of the upper ocean circulation of the South China Sea.Journal of Geophysical Research:Oceans,107(C7):22-1-22-14
Yang H Y,Wu L X,Liu H Let al,2013.Eddy energy sources and sinks in the South China Sea.Journal of Geophysical Research:Oceans,118(9):4716-4726
Yu Z,Shen S,Mc Creary J P et al,2007.South China Sea throughflow as evidenced by satellite images and numerical experiments.Geophysical Research Letters,34(1):L01601,http://dx.doi.org/10.1029/2006GL028103
Zeng X Z,Peng S Q,Li Z J et al,2014.A reanalysis dataset of the South China Sea.Scientific Data,1:140052
Zhuang W,Xie S P,Wang D X et al,2010a.Intraseasonal variability in sea surface height over the South China Sea.Journal of Geophysical Research:Oceans,115(C4):C04010
Zhuang W,Du Y,Wang D X et al,2010b.Pathways of mesoscale variability in the South China Sea.Chinese Journal of Oceanology and Limnology,28(5):1055-1067
Zu T T,Wang D X,Yan C X et al,2013.Evolution of an anticyclonic eddy southwest of Taiwan.Ocean Dynamics,63(5):519-531
王东晓,刘钦燕,谢强等,2013.与南海西边界流有关的区域海洋学进展.科学通报,58(14):1277-1288
王东晓,周发璓,秦曾灏,1996.南海上层海洋环流两层半模式的数值模拟Ⅰ.闭边界海盆季节性环流.海洋学报,18(5):30-40
李晗,王强,黄科等,2017.1992-2011年夏季南海西部离岸流区涡流相互作用特征.海洋与湖沼,48(5):912-925
曾庆存,李荣凤,季仲贞等,1989.南海月平均流的计算.大气科学,13(2):127-138
Atlas R,Hoffman R N,Ardizzone J et al,2011.Across-calibrated,multiplatform ocean surface wind velocity product for meteorological and oceanographic applications.Bulletin of the American Meteorological Society,92:157-174
Beckmann A,B?ning C W,Brügge B et al,1994.On the generation and role of eddy variability in the central North Atlantic Ocean.Journal of Geophysical Research:Oceans,99(C10):20381-20391
B?ning C W,Budich R G,1992.Eddy dynamics in a primitive equation model:Sensitivity to horizontal resolution and friction.Journal of Physical Oceanography,22(4):361-381
Cai S Q,Long X M,Wang S G,2007.A model study of the summer Southeast Vietnam Offshore Current in the southern South China Sea.Continental Shelf Research,27(18):2357-2372
Chen C L,Wang G H,2014.Interannual variability of the eastward current in the western South China Sea associated with the summer Asian monsoon.Journal of Geophysical Research:Oceans,119(9):5745-5754
Cheng X H,Qi Y Q,2010.Variations of eddy kinetic energy in the South China Sea.Journal of Oceanography,66(1):85-94
Fang G,Wang G,Fang Y et al,2012.A review on the South China Sea western boundary current.Acta Oceanologica Sinica,31(5):1-10
Fang W D,Fang G H,Shi P et al,2002.Seasonal structures of upper layer circulation in the southern South China Sea from in situ observations.Journal of Geophysical Research:Oceans,107(C11):23-1-23-12
Gan J P,Qu T D,2008.Coastal jet separation and associated flow variability in the southwest South China Sea.Deep Sea Research Part I:Oceanographic Research Papers,55(1):1-19
Geng W,Xie Q,Chen G X et al,2016.Numerical study on the eddy-mean flow interaction between a cyclonic eddy and Kuroshio.Journal of Oceanography,2016,72(5):727-745
Gill A E,2016.Atmosphere-Ocean Dynamics.Amsterdam:Elsevier
Hu J Y,Gan J P,Sun Z Y et al,2011.Observed three-dimensional structure of a cold eddy in the southwestern South China Sea.Journal of Geophysical Research:Oceans,116(C5):C05016
Ivchenko V O,Tréguier A M,Best S E,1997.A kinetic energy budget and internal instabilities in the Fine Resolution Antarctic Model.Journal of Physical Oceanography,27(1):5-22
Jia Y L,Liu Q Y,Liu W,2005.Primary study of the mechanism of eddy shedding from the Kuroshio bend in Luzon Strait.Journal of Oceanography,61(6):1017-1027
Kang D J,Curchitser E N,2015.Energetics of eddy-mean flow interactions in the Gulf Stream region.Journal of Physical Oceanography,45(4):1103-1120
Kuo Y C,Chern C S,2011.Numerical study on the interactions between a mesoscale eddy and a western boundary current.Journal of Oceanography,67(3):263-272
Li L,Xu J D,Jing C S et al,2003.Annual variation of sea surface height,dynamic topography and circulation in the South China Sea-A TOPEX/Poseidon satellite altimetry study.Science in China Series D:Earth Sciences,46(2):127-138
Li Y L,Han W Q,Wilkin J L et al,2014.Interannual variability of the surface summertime eastward jet in the South China Sea.Journal of Geophysical Research:Oceans,119(10):7205-7228
Liu Z Y,Yang H J,Liu Q Y,2001.Regional dynamics of seasonal variability in the South China Sea.Journal of Physical Oceanography,31(1):272-284
Lorenz E N,1955.Available potential energy and the maintenance of the general circulation.Tellus,7(2):157-167
Nan F,He Z G,Zhou H et al,2011.Three long-lived anticyclonic eddies in the northern South China Sea.Journal of Geophysical Research,116(C5):C05002,http://dx.doi.org/10.1029/2010JC006790
Qu T D,Du Y,Sasaki H,2006.South China Sea throughflow:Aheat and freshwater conveyor.Geophysical Research Letters,33:L23617,doi:10.1029/2006GL028350
Quan Q,Xue H J,Qin H L et al,2016.Features and variability of the South China Sea western boundary current from 1992 to2011.Ocean Dynamics,66(6-7):795-810
Shang X D,Liu Q,Xie X H et al,2015.Characteristics and seasonal variability of internal tides in the southern South China Sea.Deep Sea Research Part I:Oceanographic Research Papers,98:43-52
Shaw P T,Chao S Y,Fu L L,1999.Sea surface height variations in the South China Sea from satellite altimetry.Oceanologica Acta,22(1):1-17
Treguier A M,1992.Kinetic energy analysis of an eddy resolving,primitive equation model of the North Atlantic.Journal of Geophysical Research:Atmospheres,97:687-701
Von Storch J S,Eden C,Fast I et al,2012.An estimate of the Lorenz energy cycle for the world ocean based on the STORM/NCEP simulation.Journal of Physical Oceanography,42(12):2185-2205
Wang D X,Liu Q Y,Huang R X et al,2006.Interannual variability of the South China Sea throughflow inferred from wind data and an ocean data assimilation product.Geophysical Research Letters,33:L14605,doi:10.1029/2006GL026316
Wang D X,Xu H Z,Lin J et al,2008.Anticyclonic eddies in the northeastern South China Sea during winter 2003/2004.Journal of Oceanography,64(6):925-935
Wang G H,Su J L,Chu P C,2003.Mesoscale eddies in the South China Sea observed with altimeter data.Geophysical Research Letters,30(21):2121
Wang G H,Wang C Z,Huang R X,2010.Interdecadal variability of the eastward current in the South China Sea associated with the summer Asian monsoon.Journal of Climate,23(22):6115-6123
Wu C R,Shaw P T,Chao S Y,1999.Assimilating altimetric data into a South China Sea model.Journal of Geophysical Research:Oceans,1042(C12):29987-30005
Xiang R,Fang W D,Zhou S Q,2016.The anticyclonic circulation in the southern South China Sea:Observed structure,seasonal development and interannual variability.Journal of Marine Systems,154:131-145
Xiu P,Chai F,Shi L et al,2010.A census of eddy activities in the South China Sea during 1993-2007.Journal of Geophysical Research:Oceans,115(C3):C03012
Xue H,Mellor G L,1993.Instability of the Gulf Stream front in the South Atlantic Bight.Journal of Physical Oceanography,23:2326-2350
Yang H J,Liu Q Y,Liu Z Y et al,2002.A general circulation model study of the dynamics of the upper ocean circulation of the South China Sea.Journal of Geophysical Research:Oceans,107(C7):22-1-22-14
Yang H Y,Wu L X,Liu H Let al,2013.Eddy energy sources and sinks in the South China Sea.Journal of Geophysical Research:Oceans,118(9):4716-4726
Yu Z,Shen S,Mc Creary J P et al,2007.South China Sea throughflow as evidenced by satellite images and numerical experiments.Geophysical Research Letters,34(1):L01601,http://dx.doi.org/10.1029/2006GL028103
Zeng X Z,Peng S Q,Li Z J et al,2014.A reanalysis dataset of the South China Sea.Scientific Data,1:140052
Zhuang W,Xie S P,Wang D X et al,2010a.Intraseasonal variability in sea surface height over the South China Sea.Journal of Geophysical Research:Oceans,115(C4):C04010
Zhuang W,Du Y,Wang D X et al,2010b.Pathways of mesoscale variability in the South China Sea.Chinese Journal of Oceanology and Limnology,28(5):1055-1067
Zu T T,Wang D X,Yan C X et al,2013.Evolution of an anticyclonic eddy southwest of Taiwan.Ocean Dynamics,63(5):519-531