地震海洋学方法在海洋混合参数提取中的研究与应用--以南海内波和地中海涡旋为例  

Extraction of mixing parameters by seismic oceanography and applications:Case study of the internal waves in South China Sea and Mediterranean eddy

作　　者：拜阳[1] 宋海斌[1] 董崇志[2] 刘伯然[3,4] 陈江欣[3,4] 耿明会 

机构地区：[1]海洋地质国家重点实验室,同济大学海洋与地球科学学院,上海200092 [2]国家海洋局海底科学重点实验室,国家海洋局第二海洋研究所,杭州310012 [3]中国科学院油气资源研究重点实验室,中国科学院地质与地球物理研究所,北京100029 [4]中国科学院大学,北京100049

出　　处：《地球物理学报》2015年第7期2473-2485,共13页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(91128205,41076024,41106044);国家基础研究发展规划项目(2011CB403503);浙江省自然科学基金(LQ12D06003)资助

摘　　要：混合是海洋中普遍存在的一种海水运动形式,对多个海洋学分支的研究具有重要的影响.随着物理海洋学的研究重心从大尺度向中小尺度现象过渡,近年来混合问题的研究重心也逐渐转向了中小尺度现象.内波与中尺度涡都是非常重要的中小尺度物理海洋学现象,对海洋能量在不同尺度中的级联发挥着重要的作用.本文基于地震海洋学研究了海洋混合参数的提取方法,并以南海内波和地中海涡旋为例进行了计算和分析.结果显示,南海内波在200～600m深度范围内所引起的混合可达10^-2.79 m^2·s^-1左右,比大洋的统计结果10^-5 m^2·s^-1高出两个数量级以上.而地中海涡旋所引起的湍流混合率可达10^-3.44 m^2·s^-1左右,与大洋统计结果相比高出1.5个数量级左右,并且地中海涡旋下边界的混合要强于上边界,这一特征与前人的研究一致,另外涡旋上边界之上以及侧边界的外侧也具有非常高的混合率.Mixing is a most common movement in the ocean,which affects the studies of many oceanographic disciplines.With the development of ocean science and technology,the focus of mixing problem study has been changing from larger scales to meso and small scales.The internalwaves and meso-scale eddy are very important phenomena of such scales in physical oceanography.They both play great roles in the energy cascade for the movement of different scales in the ocean.Based on seismic oceanography,the method to extract the mixing parameters is established.Using this method,two cases are computed and analyzed ：the internal wave in South China Sea and the Mediterranean eddy.Spectral analysis is a prerequisite for the estimation of mixing parameters.Subtracting the mean depth of a horizon from a seismic section,we can get the vertical displacement of water column.Then we use the Welch method to compute the horizontal spectrum of the displacement curve. Afterwards we decompose the spectrum by EEMD（ensemble empirical mode decomposition）and extract the trend component as the fitting result.Based on this fitting result and previous theory of ocean mixing,the mixing parameters can be estimated.In the depth range of 200～600 m,the mixing rate induced by the internal waves in South China Sea can reach 10^-2.79 m^2·s^-1,which is two orders of magnitude larger than the statistical value（10^-5 m^2·s^-1）of the open ocean.The mixing rate induced by Mediterranean eddy is around 10^-3.44 m^2·s^-1,which is about 1.5orders of magnitude larger than the statistical value of the open ocean.The mixing rate of the lower boundary of the eddy is larger than the upper boundary,which agrees with the previous study.The outside part,which is close to the upper and lateral boundary,also has a high mixing rate.The mixing rate of the entire ocean should reach 10^-4 m^2·s^-1 in order to drive the large scale ocean circulation.However,the measurement of the open ocean shows that this value is just around 10^-5 m^2·s^-1,so there is a＂mixing b

关 键 词：混合 内波 中尺度涡 地震海洋学 经验模态分解 

分 类 号：P738[天文地球—海洋地质]