【作者】 林霄沛；

【导师】 吴德星；

【作者基本信息】 中国海洋大学 ， 物理海洋， 2004， 博士

【摘要】 资料分析显示季节内Rossby长波是副热带海区最显著的波动信号，其对能量、动量和热量的变化、大中尺度过程的相互作用等都有重要的作用，尤其是在北太平洋副热带海区季节内Rossby长波对台湾以东黑潮的流量和流轴位置有影响，因而对于季节内Rossby长波的研究具有重要的科学意义和现实意义。本文通过资料分析、理论推导和数值模拟结果分析，重点研究了季节内Rossby长波在副热带海区的加强机制、波速特征及其对东海黑潮的影响。 基于两层半海洋模式，导出了北太平洋副热带海域季节内Rossby长波的频散关系和对应的斜压不稳定判据，发现季节内Rossby长波在副热带海区的加强机制可能是斜压不稳定。根据该斜压不稳定判据和Levitus98气候态资料确定的北太平洋副热带海区斜压不稳定区与根据卫星高度计资料确定的季节内Rossby长波加强区的位置基本一致，进一步确证了斜压不稳定是副热带海区季节内Rossby长波的主要加强机制。北太平洋副热带海区斜压不稳定区与位涡池区的基本一致性在本文的工作中得到进一步的证实，从而可以推论北太平洋副热带海区季节内Rossby长波主要在位涡池区内加强。位涡池区随时间的变化导致波动加强区随时间的变化，北太平洋由于海盆尺度大，通风较弱，位涡池区的范围非常大，因而其波动加强区的范围也大；北大西洋由于海盆尺度小，通风较强，位涡池区的范围非常小，因而其波动加强区的范围也非常小。 对卫星高度计资料的分析显示，太平洋副热带海区由东边界反射的季节内Rossby长波波速基本上与经典线性理论预测的波速一致，在位涡池区内加强的季节内Rossby长波波速大于经典线性理论预测的波速。根据边界反射Rossby波的阈值周期理论得到的东边界反射出来的季节内Rossby长波的周期大于根据卫星高度计资料得到的在位涡池区内加强的季节内Rossby长波的周期也佐证了上述两种季节内Rossby长波的波速差异。对两层半海洋模式结果的分析表明，东边界反射出来的季节内Rossby长波基本上处于影区，温跃层内几乎不存在西向基本流，因而波速基本上与经典线性理论所预测的波速一致；在位涡池区内加强的季节内Rossby长波，由于温跃层内基本流的作用，波速大于经典线性理论所预测的波速。副热带海区季节内Rossbv长波及其对东海黑潮的影响 对验潮站海面高度资料、数值模拟结果、断面调查资料和浮标资料的分析显示，北太平洋副热带海区的季节内ROSsby长波对东海黑潮上游的流量和流轴影响较大，使得东海黑潮上游的流量变化规律主要是季节内变化，季节性变化规律不明显;由于通过琉球岛链庆良间水道进入东海流量的调节作用，大大削弱了季节内信号对东海黑潮下游的影响，使得东海黑潮下游流量的季节内变化信号不明显，主要变化规律是季节变化。对一个两层模式分析的结果表明，当季节内波动导致黑潮流量增大，流轴靠近地形比较平缓的陆架时，有利于东海黑潮不稳定波动的发生，使东海黑潮锋面发生弯曲。对卫星遥感资料的分析表明，由于平流和豁口尺度相对较大，季节内Rossby长波信号可以由台湾以东进入东海，其向下游的传播过程中可能演变为东海黑潮的锋面弯曲;而琉球岛链附近平流较弱，豁口尺度小，由岛链间进入东海的季节内Rossby长波信号较弱，对东海黑潮的影响较小。 本文的主要创新和贡献主要有以下几点。首次提出并确证了副热带海区的季节内R。SSby长波是在位涡池区内加强的，而斜压不稳定是季节内Rossby长波加强的主要机制，并解释了北太平洋和北大西洋副热带海区季节内Rossby长波加强区不同的原因;首次发现并确证在副热带海区位涡池区内加强的季节内尺ossby长波波速大于经典线性理论预测的波速，东边界反射的季节内RoSS匕y长波波速基本与经典线性理论预测的波速一致，温跃层内的基本流是位涡池区内加强的季节内Rossby长波加速的原因;首次研究了季节内Rossby长波对东海黑潮的影响，特别是首次提出了通过庆良间水道的入流对东海黑潮上游流量季节内信号的调节作用，使得在东海黑潮上游非常显著的季节内信号在东海黑潮下游大大削弱，因而造成了东海黑潮上游和下游流量变化规律的不同。更多还原

【Abstract】 The satellite altimeter data reveal that intraseasonal long Rossby wave is the most obvious wave signal in the subtropical ocean. Because it has a great effect on the variation of energy, momentum, and heat flux as well as the interaction of large and middle scale processes, and it also affects the Kuroshio in many ways, the study on the intraseasonal long Rossby wave is important and practical. Based on the data analysis, theoritic studies and numerical simulation, this paper will focus on the amplification mechanism, the character of wave speed and the effects to the Kuroshio of the intraseasonal long Rossby wave.Based on a two and half layer ocean model the long Rossby wave dispersion relation and the corresponding baroclinic instability criterion are derived. It can infer that the intraseasonal long Rossby wave may be amplified by the baroclinic instability. According to the baroclinic instability criterion the paper gives the baroclinic instability area of North Subtropical Pacific Ocean from the Levitus 98 climatic data. The baroclinic instability area is well in accord with the amplification area of the intraseasonal long Rossby wave, and this proves that the baroclinic instability is the main amplification mechanism of the intraseasonal long Rossby wave. The consistency between the baroclinic instability area and the potential vorticity (PV) pool is further proved in this paper, from which one could conjecture that the intraseasonal long Rossby wave is amplified in the PV pool. The changeable of PV pool with time leads to the variation of wave amplification area. Because the relatively large ocean basin and weak ventilation, the PV poolThe Intraseasonal Long Rossby Wave in the Subtropical Ocean and its Effect to the Kuroshio inthe East China Seais much larger in the North Pacific Ocean than in the North Atlantic Ocean. This is the reason why the wave amplification areas are much different in these two oceans.The analysis of the satellite altimeter data suggests that the propagating speed of intraseasonal long Rossby wave amplified in the subtropical Pacific ocean is faster than that of first-mode baroclinic free Rossby wave predicted by the liner theory and the propagating speed of intraseasonal long Rossby wave reflected in the eastern boundary of Pacific Ocean agrees basically with the liner theory speed of first-mode baroclinic free Rossby wave. According to the critical frequency theory this paper gives the period of intraseasonal long Rossby wave reflected in the eastern boundary of Pacific Ocean. The period of intraseasonal long Rossby wave reflected in the eastern boundary is longer than the period of intraseasonal long Rossby wave amplified in the subtropical ocean, and this also proves the speed differences of these two Rossby waves. The acceleration of the propagating speed of intraseasonal long Rossby wave amplified in the subtropical Pacific Ocean is due to the existence of westward thermolcline mean flow in the PV pool.The analysis of sea level data from tide stations and ocean general circulation model (OGCM) as well as the float data and section data shows that the intraseasonal long Rossby wave results in the intraseasonal variations of Kuroshio axis and transport in the upper reaches of the Kuroshio in the East China Sea (ECS). Due to the transport modulation induced by Ryukyu Islands, the intraseasonal variation is very weak in the lower reaches of the Kuroshio in the ECS. A two-layer model reveals the relation among Kuroshio unstable wave with topography, transport and the axis position of the Kuroshio, from which we can infer that the intrusion of intraseasonal long Rossby wave may stimulate the Kuroshio unstable wave in the upper reaches of the Kuroshio in the ECS. TheThe Intraseasonal Long Rossby Wave in the Subtropical Ocean and its Effect to the Kuroshio inthe East China Seaaltimeter data also shows that the sea level anomaly resulting from intraseasonal long Rossby wave could pass the channel between Taiwan and Ryukyu Islands and propagate northeastward in accord更多还原