南海东北部海域潮汐模式的模型参数最优估计

利用深海高度计资料对南海东北部海域潮汐模式的模型参数进行了最优同化估计。模型参数包括底摩擦系数和开边界条件。得到的最优底摩擦系数的平均值为0.0085,取值较大的区域有台湾岛的东北部和西南部及吕宋海峡,而这些海域也是内潮响应较强烈的海域。     

内孤立波绕岛三维演化特性实验研究

南海是内孤立波的多发地带,内孤立波形成后向西传播,绕过东沙岛时,波形、振幅等波参数会发生相应的变化。该文主要运用实验方法来研究内孤立波绕岛后三维特性的演化。实验中内孤立波在两层流体中传播,其中上层为清水,下层为等密度的盐水。实验技术运用荧光方法直接得到内孤立波引起的波形变化与合成孔径雷达(SAR)拍摄到的东沙群岛附近内孤立波作定性的比较,并与染色方法相结合反演出内孤立波绕岛后的各个位置处的振幅变化,体现出内孤立波绕岛后的三维演化特性。染色方法和荧光方法的结合在定性观测基础上得到了进一步的内孤立波的定量分析结果。     

大振幅内孤立波的修正Gardner传播演化模型

该文建立了简单的单一方向的修正Gardner(mG)方程用来描述强非线性内孤立波的传播演化过程。m G方程是通过调整Gardner方程的系数,从而改进了Gardner方程只能用来描述弱非线性小振幅内孤立波的缺点。修正的系数仅与上、下层流体深度比和密度比参数有关,计算的有效波长,波速和极限波幅等主要特征与经典强非线性Miyata-Choi-Camassa (MCC)方程的计算结果相符,且极限振幅与MCC模型一致,证明了m G模型对大振幅内孤立波的适用性。为了进一步研究m G模型在内孤立波传播过程中动力学特性,采用m G方程模拟内孤立波的传播和相遇问题,并与MCC模型进行对比分析,发现两者数值结果吻合良好,说明m G模型能够用来描述强非线性大振幅内孤立波的传播模拟过程。该文提出的m G模型是一种用来描述强非线性大振幅内孤立波的可靠理论模型,较之经典的MCC模型具有更简洁的方程形式,能够在数值计算中得到更稳定的结果。     

下凹内孤立波流场与横置细长潜体相互作用特性的实验研究

该文在大型重力式分层流水槽中开展横置细长潜体遭遇下凹内孤立波的流场和作用力特性的实验研究,采用PIV技术测量内孤立波及其与潜体相互作用时的流场变化,同时利用测力传感器测量潜体所受水平与垂向力的变化,分析入射波振幅以及潜体潜深变化对作用力的影响情况。研究表明:内孤立波诱导流场的整体特征表现为,在上下两层流体中形成强烈的水平剪切流,上层流速大于下层流速且方向相反,在波前后分别形成下沉与上升流动;潜体所受水平力主要由内孤立波诱导流场决定,而垂向力则由密度场与流场变化的耦合作用决定;在横置细长体遭遇内孤立波过程中,其后部产生的涡旋结构导致高密度流体团的滞留继而逐渐扩散,它是决定沿内孤立波传播方向横置与平行放置细长潜体时两者垂向作用力差异的重要原因。     

珠江三角洲河口区的潮汐分析(上)

一、引言珠江河口是一个漏斗湾和三角洲网河并存的河口区。河汉纵横交错,水流相互沟通,入海口门多达八处。口门外岛屿星罗棋布,其河口潮汐复杂程度,居全国各大河的首位。珠江河口区潮汐主要是太平洋潮波经吕宋海峡,越过南海传入珠江河口后,受地形、径流、气象等因素的影响所形成。其主要特征仍与海洋潮汐一样受天文潮制约,但河口潮汐在高低潮位、高低潮间隙、潮历时、潮差等方面又与海洋潮汐不同。     

内孤立波环境下竖直柱状物受力特征研究综述

内孤立波是海洋、近岸、河口等水体中常见的物理现象,在稳定层化水体中的密度跃层上由外界扰动诱发产生,其传播过程中所激发的剪切流会伴随着巨大的能量,对水下工程结构物的安全稳定造成严重威胁。因此,探究内孤立波与工程结构物相互作用规律具有重要意义。在整理与总结国内外众多学者研究进展的基础上,从物理试验与数值模拟2个方面介绍了内孤立波对结构物作用特性研究的常见方法,并对竖直柱状物在内孤立波环境下所受水平作用力、垂向作用力与力矩特性规律和所受水平作用力敏感性因素的研究成果进行总结。最后,对内孤立波环境下竖直柱状物受力特性相关研究后续需要关注的问题进行展望。     

三孤立波在缓坡上爬高及相互作用的实验研究

海啸波经极缓的大陆架传播至近岸浅水区时可激发由多个孤立波组成的波列。为了研究多个孤立波在斜坡上爬高和相互作用规律,该文选择坡度为1/20的斜坡模型在波浪水槽进行了等波幅三孤立波爬高的物理模型实验。采用大冲程推板式造波机和改进的Goring造波方法,有效地实现了不同波峰间距和不同相对波幅时等波幅三孤立波的造波。采用高速摄像机记录每个孤立波的爬高过程,得到每个孤立波的爬高值;定性分析了爬高过程中孤立波破碎及其相互作用对爬高的影响规律。实验结果表明:第二个孤立波和第三个孤立波受先导波回落水流的影响,破碎位置向离岸方向移动;首波的爬高放大系数基本不受后续来波的影响,其爬高放大系数与同等工况下单孤立波的测量值一致;第二个孤立波和第三个孤立波的爬高放大系数与相邻的波峰间距有关,当波峰间距增大时,爬高放大系数先减少后增加;当波峰间距增至某临界值后时,第三个孤立波的爬高放大系数将大于第二个波的爬高放大系数。最后,依据本次实验结果,提出了等波幅三孤立波在缓坡上爬高的经验公式。     

内孤立波与有航速潜体相互作用数值模拟

基于两层流体中内孤立波的KdV-mKdV理论解,采用速度入口和开管道方法进行内孤立波数值造波与消波,建立了同时具有造波、造流和消波功能的数值波流水槽。利用所建立的数值波流水槽,对内孤立波与有航速潜体相互作用问题进行了数值模拟,计算分析了受力特性。数值结果表明,内孤立波造波结果理想,消波效果显著,在内孤立波流场中有航速潜体将会受到突发性冲击载荷的作用。研究表明,利用所述方法来研究内孤立波与有航速潜体的相互作用是一条有效的途径。     

基于MPS-FEM方法数值模拟孤立波与垂直板的相互作用

该文采用基于MPS-FEM方法自主开发的无网格法流固耦合求解器MPSFEM-SJTU,数值模拟孤立波与水下垂直板的相互作用。流体部分计算采用MPS方法,结构部分计算采用FEM方法,二者在接触面处采用核函数插值进行耦合。首先做了数值造波验证,孤立波采用推板造波。然后对比分析了孤立波分别与垂直刚性板和弹性板相互作用的差异。最后讨论分析板的弹性模量对孤立波与垂直板相互作用的影响。结果表明,弹性板对孤立波演化的影响与刚性板不同,同时板受到的压力也因为板的弹性模量的变化而不一样。     

北京城市水灾管理战略研究

一、北京城市水灾管理现状 1．水灾危害 北京市地处山前迎风带,两部、北部和东北部群山环绕,特殊的地形特征和气候条件,决定了该地区是暴雨多发区。特别是近10年,城市化进程加快．特殊的地貌使城市热岛效应凸显,局地突发性天气特征明显,短时暴雨等灾害性天气异常增多。因暴雨发生发展多受本地地貌影响,生成速度快,造成积涝灾害快。     

EXTRACTION OF INTERNAL TIDE FROM CURRENT

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＩｎｔｅｒｎａｌｗａｖｅｓｍａｙｅｘｉｓｔｉｎａｎｙｂｏｄｙｏｆｗａｔｅｒｗｉｔｈｄｅｎｓｉｔｙｓｔｒａｔｉｆｉｃａｔｉｏｎ (Ｏｓｂｏｒｎｅ ,1 978) .Ｌａｒｇｅ ａｍｐｌｉｔｕｄｅｉｎｔｅｒｎａｌｗａｖｅｓａｒｅｖｅｒｙｉｍｐｏｒｔａｎｔｆｏｒｐｏｒ ｂｌｅｍｓｏｆａｃｏｕｓｔｉｃａｌｃｏｍｍｕｎｉｃａｔｉｏｎｏｖｅｒｌａｒｇｅｄｉｓ ｔａｎｃｅｓ,ｆｏｒｈｙｄｒａｕｌｉｃｅｎｇｉｎｅｅｒｉｎｇｏｆｄｅｅｐｗａｔｅｒｃｏｎ ｓｔｒｕｃｔｉｏｎｓａｎｄｆｏｒｔｈｅｓａｆｅｔ…     

DYNAMICS OF THE KUROSHIO INTRUSION INTO THE SOUTHEAST CHINA ADJACENT WATERS-A NUMERICAL STUDY

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｗｅｓｔｗａｒｄｉｎｔｒｕｓｉｏｎｏｆｔｈｅＫｕｒｏｓｈｉｏｏｃｃｕｒｓｉｎｔｈｅＬｕｚｏｎＳｔｒａｉｔａｎｄｏｆｆＴａｉｗａｎｎｏｒｔｈｅａｓｔｃｏａｓｔ.Ｔｈｅｂｅｈａｖｉｏｒｓａｎｄｓｔｒｕｃｔｕｒｅｓｏｆｔｈｅｉｎｔｒｕｄｉｎｇｆｌｏｗｓｈａｖｅｂｅｅｎｓｔｕｄｉｅｄｂｙｍａｎｙｏｃｅａｎｏｇｒａｐｈｅｒｓ ,ｙｅｔｎｏｔｆｕｌｌｙｋｎｏｗｎ .Ｔｈｅｄｙｎａｍｉｃａｓｐｅｃｔｓｏｆｔｈｅｉｎｔｒｕｓｉｏｎｈａｖｅｂｅｅｎｓｔｕｄｉｅｄｂｙｆｅｗｉｎｖｅｓｔ…     

Effects of high-order nonlinearity and rotation on the fission of internal solitary waves in the South China Sea

A variable coefficient, rotation-modified extended Kortweg-deVries (vReKdV) model is applied to the study of the South China Sea (SCS), with focus on the effects of the high-order (cubic) nonlinearity and the rotation on the disintegration process of large-amplitude (170 m) Internal Solitary Waves (ISWs) and the semi-diurnal internal tide propagating from the deep basin station to the slope and shelf regions in a continuously stratified system. The numerical solutions show that the high-order nonlinearity significantly affects the wave profile by increasing the wave amplitude and the phase speed in the simulated area. It is shown that the initial KdV-type ISW will decay faster when the rotation dispersion is considered, however the wave profile does not change significantly and the rotation effect is not important. The simulations of the semi-diurnal internal tide indicate that the phase of the wave profile is shifted earlier when the rotation effect is included. A solitary wave packet emerges on the shelf, and the wave speed is also greater when considering the rotation dispersion. In addition, the effects of the background currents are discussed further in this paper. It is found that the background currents generally change the magnitude and occasionally change the sign of the nonlinear coefficients in the northern SCS.     

SOME FEATURES OF RING 94S-A KUROSHIO DETACHED EDDY IN THE SOUTH CHINA SEA

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＩｎＳｅｐｔｅｍｂｅｒ 1 994,ａｗａｒｍ ｃｏｒｅｒｉｎｇｗａｓｄｉｓ ｃｏｖｅｒｅｄｎｅａｒｔｈｅｃｏｎｔｉｎｅｎｔａｌｓｌｏｐｅｏｆｔｈｅｎｏｒｔｈｅｒｎＳｏｕｔｈＣｈｉｎａＳｅａ (ＳＣＳ ,ｈｅａｒａｆｔｅｒ) ,ａｎｄｗａｓｄｉｓ ｃｕｓｓｅｄｉｎｄｅｔａｉｌｆｏｒｔｈｅｆｉｒｓｔｔｉｍｅ (Ｌｉｅｔａｌ.,1 997;Ｌｉｅｔａｌ.,1 998) .Ｔｈｉｓｒｉｎｇ (Ｒｉｎｇ 94Ｓ ,ｎａｍｅｄａｆｔｅｒｔｈｅｏｂｓｅｒｖｅｄｙｅａｒａｎｄｍｏｎｔｈ)ｉｓａｎｗａｒｍｃｏｒｅａｎｔｉ ｃｙ…     

THE EFFECTS OF MONSOONS AND CONNECTIVITY OF SOUTH CHINA SEA ON THE SEASONAL VARIATIONS OF WATER EXCHANGE IN THE LUZON STRAIT

Seasonal variations of water exchange in the Luzon Strait are studied numerically using the improved Princeton Ocean Model (POM) with a consideration of the effects of connectivity of South China Sea (SCS) and monsoons. The numerical simulations are carried out with the strategy of variable grids, coarse grids for the Pacific basin and fine grids for the SCS. It is shown that the Mindoro Strait plays an important role in adjusting the water balance between the Pacific and the SCS. The SCS monsoon in summer seasons hinders the entrance of the Pacific water into the SCS through the Luzon Strait while the SCS monsoon in winter seasons promotes the entrance of Pacific water into the SCS through the Luzon Strait. However, the SCS monsoon does not affect the annual mean Luzon Strait transport, as is mainly determined by the Pacific basin wind.     

Marine renewable energy in China： Current status and perspectives

Based on a general review of marine renewable energy in China, an assessment of the development status and amount of various marine renewable energy resources, including tidal energy, tidal current energy, wave energy, ocean thermal energy, and salinity gradient energy in China＇s coastal seas, such as the Bohai Sea, the Yellow Sea, the East China Sea, and the South China Sea, is presented. We have found that these kinds of marine renewable energy resources will play an important role in meeting China＇s future energy needs. Additionally, considering the uneven distribution of China＇s marine renewable energy and the influences of its exploitation on the environment, we have suggested several sites with great potential for each kind of marine energy. Furthermore, perspectives on and challenges related with marine renewable energy in China are addressed.     

Numerical analysis of impacts of 2011 Japan Tohoku tsunami on China Coast

On the 11th of March, 2011, a subduction earthquake of magnitude Mw9.0 happened at the northeast of Japan, generating a tsunami which resulted in huge damage in Japan. Okada’s elastic fault model is used to generate the deformation of the sea bottom based on USGS sources and UCSB sources respectively. The shallow water equations are solved by the adaptively refined finite volume methods so that it can compute the propagation of tsunami in the Pacific Ocean efficiently. The computed time series of the surface elevation are compared with the measured data from NOAA real-time tsunami monitoring systems for model validation, and UCSB sources derive better results than USGS sources. Furthermore, one nested domain with fine grid and higher topography resolution is combined to compute numerically this tsunami spreading in the Bohai Sea, Yellow Sea, East China Sea, and North of South China Sea. The impacts on China Coast and seas are analyzed and discussed. The results show that the tsunami has almost no impact in the Bohai Sea and Yellow Sea. It has some kind impact on the East China Sea and South China Sea. However, maximum wave height on China Coast is smaller than 0.5 m. It is thus concluded that the 2011 Tohoku tsunami did not generate a significant influence on China Coast.     

基于GPU并行的厦门附近海域潮波传播数值模拟研究

厦门周边海域岛屿众多,潮汐汊道交错,水流运动复杂,本文针对该海域开展基于GPU并行的潮波传播精细化模拟研究。基于GPU并行算法构建了厦门附近海域高分辨率二维潮流数学模型,计算效率与单核CPU相比,可提高约180倍。模拟计算了2019年全年厦门周边海域的潮波传播,研究表明,厦门岛附近潮量主要来自厦门湾,潮波自外海向九龙江口方向传播,高潮位逐渐升高,低潮位逐渐降低。同安湾方向潮波受厦门湾和围头湾两股潮波影响,其潮波特性与围头湾更为相似。厦门海域M2分潮占绝对主导地位,其振幅占所有分潮的41.2%,全日分潮K1分潮振幅值最大,同安湾与九龙江口M2分潮振幅接近,K1分潮九龙江口振幅较大,潮波变形程度同安湾较大。     

SAR IMAGING SIMULATION OF HORIZONTAL FULLY TWO-DIMENSIONAL INTERNAL WAVES

1. INTRODUCTION The ability of Synthetic Aperture Radar (SAR) to measure ocean waves has been widely proved since the launch of Seasat in 1978[1] Compared with traditional in-situ instruments, SAR is superior for its wide spatial coverage and high spatial…