利用卫星测高资料精密定量研究全球海洋环流及其变化

发布时间：2018-02-03 22:10

本文关键词： 卫星测高卫星重力海洋环流稳态海面地形涡动能中国南海黑潮黑潮延伸体气候变化　出处：《武汉大学》2014年博士论文　论文类型：学位论文

【摘要】：海洋环流作为各大洋联系的纽带,使得世界大洋的各种水文、化学要素以及热盐等状况得以保持长期相对的稳定。海洋环流与大气之间的相互耦合作用直接或间接地影响了全球和区域气候变化。近几十年来,气候和全球环境变化的成因、规律及其与地球系统各个分支之间的关系受到了科学家的高度重视。因此,精确地确定全球各主要海洋环流及其运动变化规律,对于气象学和物理海洋学以及其他相关地球科学均具有十分重要意义。经过近百年发展,利用传统物理海洋学手段对海洋环流的研究已取得了丰硕成果。然而,由于数据仍不甚完善,存在数据区域偏差和较大的数据空白区,难以实现全球均匀覆盖,无法满足精细和长时间尺度变化特征研究的需求。在过去20多年,卫星测高技术的发展和日趋成熟,使我们对海洋有了更进一步的认识。它革命性地改变了传统海洋测量模式,极大地丰富了海洋观测数据,使得全球海洋环流研究有了重大进展。本文联合多源卫星测高资料确定的全球平均海面高模型和海平面异常变化时间序列以及新一代地球重力场模型,研究建立高精度、高分辨率全球稳态海面地形的理论与方法,提取分析全球和部分特殊海域海洋环流变化特征,并分析黑潮及其延伸体主轴变异特征,探讨海洋环流与气候变化之间的关系。主要研究工作和成果包括： (1)从动力学角度阐述了海流的基础理论,包括海流运动方程、连续方程和边界条件,推导了地转流基本方程,总结了稳态海面地形计算中的两种基本方法,并对其计算过程中的基准统一、永久潮汐改正和噪声滤波等细节问题进行了探讨,为进一步利用多源卫星测高数据研究海洋环流提供了理论依据。 (2)基于WHU2009全球平均海面高模型,采用GO_GONS_2_TIM-R4、 GOCO03S、ITG-GRACE2010S和EIGEN-CHAMP05S四种典型的地球重力场模型分别计算稳态海面地形模型及相应海洋环流模式,并与国际常用模型CLS09和DTU10进行比较分析,验证了GOCE重力场高阶部分在提高海洋环流确定精度中的极大贡献,同时经逐阶次比较发现GOCE重力场的中低阶部分也同样表现出不可忽视的推进作用。 (3)发展了高分辨率全球稳态海面地形的建立方法,联合WHU2009平均海面高模型和最新GOCE超高阶地球重力场模型EIGEN-6C3stat,提出了最优噪声滤波半径的判别标准,建立了全球6’×6’稳态海面地形模型WHU2014MDT及相应海洋环流模式,与国际常用模型、/M08-HR和DTU13MDT的差值结果分析表明,WHU2014MDT模型精度优于VM08-HR模型。将三种模型的海洋环流结果分别与DAC实测数据进行了比较分析,WHU2014模型在全球主要海流区域均优于VM08-HR结果,特别是在海流特征最为复杂的巴马交汇海域,本文结果均优于VM08-HR和DTU13。 (4)联合多源卫星测高资料确定的海平面异常数据,提取了全球海洋环流U、V分量的速度异常变化时间序列,两者均具有微弱的线性减弱趋势,年际变化速度为-0.045和-0.006(mm/s)/a。通过频谱分析发现,U、V方向速度异常的变化均存在较强的季节性信号及较弱的年代际变化特征,其中U方向的季节性信号主要集中在赤道附近的热带海域以及湾流、黑潮延伸体和南极绕极流等大尺度强流所在海域,而V方向分量在赤道附近海域的季节性信号较弱,仅在阿拉伯海及湾流等大尺度强流附近存在较强的信号。将噪声平滑后的U、V分量速度异常变化时间序列与表征厄尔尼诺／拉尼娜现象的南方涛动指数(SOI)进行了比较,发现两者与SOI指数具有很好的负相关性,相关指数分别为-0.65和-0.62。 (5)在(4)研究成果的基础上,进一步提取了全球海洋环流涡动能(EKE)的变化时间序列。全球EKE区域性差异明显,在黑潮及其延伸体、湾流、南极绕极流、厄加勒斯暖流、巴马交汇等具有大尺度强流的区域EKE能量较高,此外,在阿拉伯海、中国南海等涡流频发区域也具有较高的EKE。在本文研究时间范围内,全球EKE整体近似处于“能量守恒”状态,1992.10.14至2013.04.17期间的线性趋势为-1.04cm2/s2,年际变化速度为-0.05(cm2/s2)/a。对全球EKE变化时间序列进行频谱分析发现,其最显著的变化特征是季节性变化和准10a年代际振荡,此外还有1.3a、3.3a和6.5a较为显著的变化周期。分析了涡动能EKE和稳态动能MKE之间的关系,得到了湾流南部、黑潮、南极绕极流北部、阿拉伯海和中国南海等海域是中尺度涡高发区域的结论。 (6)将中国南海作为典型区域进行了重点研究,分析了南海涡动能(EKE)的时空变化特征。南海EKE整体上具有明显的下降趋势,线性变化趋势为-12.3cm2/s2,年际变化速度为-0.6(cm2/s2)/a。南海EKE因多种尺度叠加而呈现较为复杂的结果,具有两个能量高值中心,分别位于越南东部海域和台湾西南海域。南海EKE最显著的变化尺度是季节性变化,其季节性信号受越南东部海域的季节性变化所控制,同时该区域EKE的季节性变化主要受局部地区风应力旋度季节性变化的影响。台湾西南海域的季节性信号较弱,其年际内和中尺度变化显著,主要受黑潮入侵南海和冷、暖涡的相互作用所影响。与SOI相关性分析发现,厄尔尼诺现象对南海EKE具有一定的影响,两者相关系数为0.38。 (7)研究了利用卫星测高数据提取黑潮主轴的准则,并进一步计算分析了黑潮主轴的变化特征。黑潮主轴相对稳定,具有微弱的北向偏移趋势,且季节性信号显著,其中在日本南部黑潮,其主轴变异受该区域EKE变化的影响。与SOI指数比较后发现,厄尔尼诺/拉尼娜现象对该区域的黑潮主轴具有较为明显的影响,厄尔尼诺现象的发生将引起黑潮主轴向南偏移,且台湾东部黑潮滞后4-6个月、东海黑潮滞后10-12个月、日本南部黑潮滞后10-11个月。 (8)研究发现了黑潮延伸体存在两个不同的模式：1993-1995、2002-2005和2010-2012期间的稳定模式和1996-2001、2006-2009期间的非稳定模式。相对于黑潮主轴,黑潮延伸体主轴位置变化更为强烈,其中上游变化速度为0.03°/a,下游为0.05°/a,其最显著的变化特征是准10a的年代际振荡,此外还有较强的周年变化特征。南部再循环流与黑潮延伸体具有密切的关系,其强度变化与黑潮延伸体上游强度变化相关性较强,去除高频信号之后相关系数达0.5。其中心位置变化与上、下游主轴位置变化同样具有很强的相关性,去除高频信号之后相关系数达0.75和0.69。通过与太平洋年代际震荡(PDO)比较分析发现,黑潮延伸体与PDO变化具有一定的负相关性,黑潮延伸体上、下游主轴及南部再循环流中心位置与PDO的相关系数分别为-0.48、-0.47、-0.61,其中黑潮延伸体变化滞后4年左右。
[Abstract]:As the link between ocean circulation and ocean circulation , ocean circulation plays a long - term and relatively stable condition . The mutual coupling between ocean circulation and atmosphere has a great significance for the research of global and regional climate . In this paper , the global average sea surface height model and sea level anomaly change time series and the new generation of earth gravity field model are established by combining multi - source satellite survey data . The theory and method of establishing high - precision and high - resolution global steady - state sea surface topography are established . The characteristics of ocean circulation changes in the global and part of special sea areas are analyzed , and the relationship between ocean circulation and climate change is analyzed . The main research work and achievements include : ( 1 ) The basic theory of ocean current is expounded from the dynamic angle , including the sea - flow movement equation , the continuous equation and the boundary condition , and the basic equations of the earth - sea surface topography are derived . The two basic methods in the calculation of the steady - state sea surface topography are summarized , and the details such as the baseline unification , the permanent tide correction and the noise filtering in the calculation process are discussed , which provides the theoretical basis for the further study of the ocean circulation using the multi - source satellite measurement data . ( 2 ) Based on the global average sea surface model of WHU2009 , the steady - state sea surface topography model and the corresponding ocean circulation model are calculated using four typical earth gravity field models of GO _ GONS _ 2 _ TIM - R4 , GOCO03S , ITG - GRACE2010 S and EIGEN - CHAMP05S , and compared with the commonly used models CLS09 and DTU10 , the high - order part of GOCE gravity field is verified to be a great contribution to improve the accuracy of ocean circulation determination . ( 3 ) The method of establishing the high - resolution global steady - state sea surface topography is developed , the average sea surface height model of WHU2009 and EIGEN - 6C3stat of the latest GOCE ultra - high - order earth gravity field model are developed . The results of the difference between the global 6 ' 脳 6 ' steady - state sea surface terrain model and the corresponding ocean circulation model are put forward . The results of the difference between the global 6 ' 脳 6 ' steady - state sea surface terrain model WHU4MDT and DTU13MDT show that the WHU2014 model is superior to the VM08 - HR results . The WHU2014 model is superior to the results of VM08 - HR in the world ' s main ocean current region , especially in the most complex sea area of Alabama . The results are better than those of VM08 - HR and DTU13 . ( 4 ) Based on the data of sea level anomaly determined by multi - source satellite altimeter data , the velocity anomaly change time series of global ocean circulation U and V components is extracted . Both of them have strong seasonal signal and weak interdecadal variation characteristics . On the basis of ( 4 ) research results , the change time series of the global ocean circulation eddy kinetic energy ( EKE ) is further extracted . The global EKE regional difference is high . In addition , the global EKE has a high energy conservation area . In addition , in the Arabian Sea , the global EKE is approximately in the energy conservation state , and the annual variation speed is - 0.05 ( cm2 / s2 ) / a . In this paper , the relationship between the eddy kinetic energy EKE and the steady - state kinetic energy MKE is analyzed . The conclusion is obtained in the southern part of the Gulf Stream , the black tide , the Antarctic Circumpolar flow in the north , the Arabian Sea and the South China Sea . The seasonal variation of EKE in the South China Sea is dominated by seasonal variation of wind stress in the eastern part of Vietnam . The seasonal variation of EKE in South China Sea is mainly influenced by seasonal variation of wind stress in the eastern part of Vietnam . The seasonal variation of EKE in South China Sea is mainly influenced by seasonal variation of wind stress in the eastern part of Vietnam . ( 7 ) The criterion for extracting the black tide spindle from the satellite height measurement data is studied , and the variation characteristics of the black tide main shaft are further calculated . The black tide main shaft is relatively stable , has a weak north - to - shift trend , and the seasonal signal is remarkable . ( 8 ) The study shows that there are two different modes : stable model between 1993 - 1995 , 2002 - 2005 and 2010 - 2012 and unstable mode between 1996 - 2001 and 2006 - 2009 .

【学位授予单位】：武汉大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：P228.3;P731.27

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