veKdv方程的若干系数在南海北部的地理分布特征及其季节变化分析  

Analysis of geographical and seasonal variability of the variable-coefficients extended Korteweg-de Vries equation in the northern South China Sea

作　　者：廖光洪[1,2] 黄韦艮[1,2] 袁耀初[2] 徐晓华[2] 杨成浩[2] 王惠群[2] 陈洪[2] 

机构地区：[1]中国海洋大学信息科学与工程学院,山东青岛266003 [2]卫星海洋环境动力学国家重点实验室,国家海洋局第二海洋研究所,浙江杭州310012

出　　处：《海洋学报》2013年第5期46-58,共13页

基　　金：973计划项目(2011CB403503;2012CB955601);国家海洋局第二海洋研究所基本科研业务费专项(JG1302;JG1009);国家自然科学基金(41376033);全球变化与海气相互作用专项;科技部国际合作(2006DFB21630)

摘　　要：应用中国近海及邻近海域海洋再分析资料(简称CORA)研究南海北部第一模态内波场运动学参数的地理分布特征及其季节变化。首先分析了Brunt-Visl频率的统计特征;其次,基于弱非线性变系数扩展Kortewed-de Vries(veKdv)方程模型,计算了它的输入系数,即线性长波相速度,平方和立方非线性系数和频散系数,这些参数可用于定性评估内孤立波传播可能的极性,内孤立波的形态,幅度限制以及传播速度等。分析结果表明,南海北部季节性密度跃层从2月开始出现,最大浮力频率约在20m。它在6—7月达到最强,自8月开始减弱,在10月消退。另一密度跃层出现在8—11月,最大浮力频率约在80m,冬季大致在120m。季节性密度跃层在4—9月十分明显,而8—10月双跃层现象显著,冬季仅出现较弱的第二密度跃层。在1—3月和10—12月海盆深水区最大Brunt-Visl频率值要大于陆架浅水区;而在5—9月情况则相反。Brunt-Visl频率最大值所在深度随季节变化显著,冬季最深,6—7月则最浅。计算的线性内波相速度、频散系数和幅度放大因子的空间特征主要取决于地形变化;平方(立方)非线性系数与地形关系较小,随季节变化明显,它们主要取决于局地海洋环境特征。通过分析veKdv方程的系数特征,解释了为何在夏季南海北部最容易观测到大振幅内孤立波和在吕宋海峡以东海域难以观测到孤立波的原因。The phenomena of internal waves in the northern South China Sea show remarkable seasonal and interannual variance from satellite image.On the basis reanalysis data,the stratification characteristics,and the geographical and monthly variability of the veKdv equation coefficients,are analyzed.Seasonal pycnocline with maximal buoyancy frequency at about 20mdepth,begins to appear in February,is strongest in June and July,weakens in August,starts to dissipate in October.Another deeper pycnocline appears with maximal buoyancy frequency at about 80mdepth during August and November,and maximal buoyancy frequency moves to 120mdepth in winter.The seasonal pycnocline is very distinct from April to September.The double pycnocline is obvious from August to October.In winter,only the second pycnocline exists.Maxima buoyancy frequency in deeper basin is higher than that in shallow shelf area from January to March and from October to December,the configuration is opposite during May and September.The depth of maxima buoyancy frequency varies with season.It is deepest in winter,and is shallowest in June and July.It is shown that the variations of the long wave phase speed,the dispersion parameter and amplitude factor are mainly related to topography characteristics without obvious seasonal variation.The quadratic nonlinear parameter is very sensitive to variations of the vertical stratification,and the cubic nonlinear parameter depends on water depth and stratification condition.Holding higher occurrence in summer in the NSCS and the scarce existence of nonlinear internal wave on east of the Luzo Strait is interpreted by analyzing theses coefficient characteristic.

关 键 词：非线性内波 veKdv方程 运动学参数 南海北部 中国海洋再分析系统 

分 类 号：P731.2[天文地球—海洋科学]