非线性随机表面Kirchhoff散射模式

自从Longuet-Higgins(1963)根据非线性作用导出较正态分布为准确的波面高度分布以来,高阶矩在军事、高科技等很多方面得到了应用。Huang等(1980)曾检验了高阶非线性分布,他们发现当波高概率分布中包含直至四阶项时与观测结果相符,但如果考虑更高阶不但效果不好,反而更差。尽管非线性随机过程在海浪理论中获得了广泛的应用,但对海面雷达散射研究仅讨论到三阶矩的影响(Fung et al.,1991;Chen et al.,1992)。电磁随机表面散射理论有适应大尺度随机起伏的粗糙面的Kirchhoff散射模式、轻度粗糙表面的微扰散射模式、大小尺度独立叠加的双尺度散射模式、全波散射模式(Bahar,1987)和积分方程散射模式(Chen et al.,1992)等。对随机粗糙Kirchhoff表面电磁波散射问题,尽管几十年来许多科学家已经进行了大量研究(Fung et al.,1991; Ulaby et al.,1982;Wu et al.,1988),Eom等(1983)曾对Gaussian面和非 Gaussian面的散射特性进行了比较研究,Fung等(1991)将Kirchhoff散射模式推广应用到三阶粗糙随机表面,然而更高阶矩对散射截面的影响还未见报道。本文在Fung等(1991)的基础上将Kirchhoff散射模式推广应用到四阶项,并对模式的应用进行了分析和讨论。     

南沙海区微表层的研究——pH、碱度、密度和表面张力的测定

对南沙海区部分站位微表层和次表层的ｐＨ、碱度、密度和表面张力进行了测定。结果表明：微表层的表面张力低于次表层的表面张力,并且表面张力与溶解有机碳（ＤＯＣ）相关;微表层的ｐＨ低于次表层的ｐＨ,并探讨了其原因;微表层的碱度和密度一般高于次表层,同时对其原因进行了探讨。     

Effect of surface wave breaking on the surface boundary layer of temperature in the Yellow Sea in summer

Near-surface enhancement of turbulent mixing and vertical mixing coefficient for temperature owing to the effect of surface wave breaking is investigated using a two-dimensional (2-D) ocean circulation model with a tidal boundary condition in an idealized shelf sea. On the basis of the 2-D simulation, the effect of surface wave breaking on surface boundary layer deepening in the Yellow Sea in summer is studied utilizing a 3-D ocean circulation model. A well-mixed temperature surface layer in the Yellow Sea can be successfully reconstructed when the effect of surface wave breaking is considered. The diagnostic analysis of the turbulent kinetic energy equation shows that turbulent mixing is enhanced greatly in the Yellow Sea in summer by surface wave breaking. In addition, the diagnostic analysis of momentum budget and temperature budget also show that surface wave breaking has an evident contribution to the turbulent mixing in the surface boundary layer. We therefore conclude that surface wave breaking is an important factor in determining the depth of the surface boundary layer of temperature in the Yellow Sea in summer.     

Viscous free surface effect on coastal embankment hydrodynamics

A finite-differnece method was used to calculate the nonlinear hydrodynamic pressures acting on the coastal embankment faces by seismic-wave actions. The nonlinearity of free surface flow, convective acceleration, viscosity and surface tension of fluid are included in the analysis. The kinematic and dynamic free surface boundary conditions are employed for calculating the horizontal fluid velocity, pressure at the free surface and the surface profile of the fluid. The time-dependent water surface is transformed to the horizontal plane, and the flow field is mapped onto a rectangular, making it convenient to model the complex sea bottom geometry and the wavy water surface by the finite-difference method. Fully nonlinear and weakly nonlinear dynamic free surface conditions are used and compared. The effects of surface tension of fluid are also discussed. The nonslip boundary condition is applied on the most part of the interface between fluid and solid face, except the region near the intersection between free surface and wall face. The numerical results are presented for various water depths and ground motion intensities, and their associate viscous effects on coastal embankment hydrodynamics are discussed.     

太平洋海面粗糙度的计算及波长的提取

海面粗糙度对于海洋工程和海洋军事非常重要,但是海面粗糙度的现场观测资料非常少,波长更难观测。本文利用TOPEX高度计风速资料,实现了对海面粗糙度的反演。给出了一种提取波长的方法,通过验证表明利用该方法得到的波长精度较高。     

卫星高度计绝对定标中海面高梯度的计算

给出了通过平均海面高模型计算海面高梯度的具体方法,选择DTU13、CNES_CLS15、WHU2013 3种模型计算了不同海域近岸比较点海面高梯度值,随机选择的30个近岸比较点处的计算结果表明:使用3种模型计算得到的海面高梯度值之间的标准差均值为0.19cm/km。在卫星高度计定标的具体应用中,由海面高梯度得到的海面高差改正量的误差应不超过0.3cm。     

最小二乘支持向量机构造海底趋势面研究

为了解决海底趋势面的构造问题,提出了利用最小二乘支持向量机(LS-SVM)重构海底趋势面的方法,并将该方法与趋势面滤波方法进行了分析和比较,同时利用定理证明,趋势面滤波所构造的趋势面只是LS-SVM取特定参数时的解。通过实测算例表明,在构造海底趋势面的过程中,可以通过调整LS-SVM的参数,使其构造的趋势面具有更好的适用性及稳定性,更能反应海底地形的实际情况。     

外定标中海面参数对发射率影响研究

星载微波辐射计外定标的关键问题是通过辐射传输方程计算天线入瞳处亮温。根据辐射传输方程,海面成份对亮温的影响包括海面的微波辐射和对下行大气辐射的反射,其中的关键参数分别为海面发射率ep和海表面反射率R。文中对平静海面Fresnel反射率模式和粗糙海面反射率模式进行了研究分析,在此基础上着重研究了海面温度TS、海面盐度SS、海面风速W、以及观测角度θ等物理参数对海面发射率ep的影响,进而分析了这些物理参数的测量误差对亮温的计算精度的影响。     

表层海水硅同位素的分布特征及其影响因素

本文分析了采集自太平洋、印度洋和大西洋的表层海水溶解硅酸盐的δ30Si值,结果表明,太平洋表层海水的δ30Si值为0.45‰～2.91‰,平均值为(1.52±0.59)‰;印度洋表层海水的δ30Si值为0.98‰～2.30‰,平均值为(1.52±0.36)‰;大西洋表层海水的δ30Si值为0.90‰～2.23‰,其平均...     

利用卫星高度计风速资料研究海面粗糙度

海面粗糙度对于海洋工程和海洋军事都非常重要,但对海面粗糙度的现场观测资料非常少, 这大大制约了对海面粗糙度的认识。利用 TOPEX 高度计风速资料实现了对海面粗糙度的反演,并利用 1993 年和1998 年两年的资料对西北太平洋海域的海面粗糙度进行了研究。     

Surface available gravitational potential energy in the world oceans

Satellite altimetry observations, including the upcoming Surface Water and Ocean Topography mission, provide snapshots of the global sea surface high anomaly field. The common practice in analyzing these surface elevation data is to convert them into surface velocity based on the geostrophic approximation. With increasing horizontal resolution in satellite observations, sea surface elevation data will contain many dynamical signals other than the geostrophic velocity. A new physical quantity, th...     

贻贝(Mytilus edulis Linnaeus)唇瓣的扫描电镜观察

本文运用扫描电子显微镜技术研究了贻贝唇瓣的形态结，结果表明，贻贝唇瓣外部形态呈羽毛状，分为光滑面和皱褶面；褶皱面表面被覆浓密纤毛，分有沟嵴和无嵴两部分，界限明显，光滑面纤毛较少，呈簇状，分布不均，在褶皱面中央分界处和光滑面的一侧，有大量球状突起，为杯状细胞所在，纤毛和粘液在食物分拣和运输中起重要作用。     

On observing underwater objects through a wavy water surface: A new algorithm for image correction and laboratory experiment

The possibility of correcting refraction distortions in images of the sea bottom or an underwater object observed through a wavy water surface is studied. A fast-operating algorithm of recovering the “regular” image by its random realization and spatial distribution of surface slopes at the instant of observation has been proposed and approbated. A technique of determining surface slopes by the surface image with the following correction of the underwater object image based on the data about the surface slopes has been developed under conditions of a laboratory experiment.     

Correcting the errors in the initial conditions and wind stress in storm surge simulation using an adjoint optimal technique

An adjoint data assimilation methodology is applied to the Princeton Ocean Model and is evaluated by obtaining “optimal” initial conditions, sea surface forcing conditions, or both for coastal storm surge modelling. By prescribing different error sources and setting the corresponding control variables, we performed several sets of identical twin experiments by assimilating model-generated water levels. The experiment results show that, when the forecasting errors are caused by the initial (or surface boundary) conditions, adjusting initial (or surface boundary) conditions accordingly can significantly improve the storm surge simulation. However, when the forecasting errors are caused by surface boundary (or initial) conditions, data assimilation targeting improving the initial (or surface boundary) conditions is ineffective. When the forecasting errors are caused by both the initial and surface boundary conditions, adjusting both the initial and surface boundary conditions leads to the best results. In practice, we do not know whether the errors are caused by initial conditions or surface boundary conditions, therefore it is better to adjust both initial and surface boundary conditions in adjoint data assimilation.     

叶绿素a与初级生产力之间的相关关系

利用日本以南海域调查资料,对表层叶绿素a含量(SC)、真光层内叶绿素a积分值(IC)及初级生产力(PP)之间的相关关系作检验。研究表明:在高生产力海域SC、IC和PP之间存在显著的相关性,SC可以作为水域中浮游植物现存量及其生产状况的指标。在低生产力海域SC、IC和PP三者之间均不相关。文章分析了SC、IC和PP三者相关性差异的原因,指出用SC作为浮游植物现存量及其生产力指标时应持谨慎态度。     

区域海气耦合模式FROALS模拟的西北太平洋环流及其年际变率

本文利用区域海气耦合模式FROALS(Flexible Regional Ocean-Atmosphere-Land System)对西北太平洋地区1984-2007年连续积分结果,对比SODA(Simple Ocean Data Assimilation)同化资料讨论了西北太平洋海表温度和表层洋流的气候态及年际变率。结果表明,FROALS基本能够再现冬、夏季季节平均的海温型,但均存在一个明显的冷偏差;FROALS对气候平均态的表层洋流有较高的模拟技巧,对于冬、夏季的表层洋流型都能够再现。另外,表层洋流的模拟偏差与海表高度的模拟偏差直接相关。由于模式模拟的黑潮热输送较观测偏强,使得模式模拟的海洋热输送倾向于使黑潮路径上的海温呈现正偏差。从表层洋流的年际变率来看,模式模拟的与ENSO(El Nio-South Oscillation)相联系的年际变率信号与观测相似:在El Nio年,北赤道流和棉兰老流增强,低纬度西太平洋海表高度降低,而在La Nia年则呈现出相反的形态,但是在模式中这种信号稍强于观测。     

Altimetric Algorithm and Errors of Ocean Altimetry Using GNSS Reflection Signals

As a new remote sensing technology, the global navigation satellite system (GNSS) reflection signals can be used to collect the information of ocean surface wind, surface roughness and sea surface height. Ocean altimetry based on GNSS reflection technique is of low cost and it is easy to obtain large amounts of data thanks to the global navigation satellite constellation. We can estimate the sea surface height as well as the position of the specular reflection point. This paper focuses on the study of the algorithm to determine the specular reflection point and altimetry equations to estimate the sea surface height over the reflection region. We derive the error equation of sea surface height based on the error propagation theory. Effects of the Doppler shift and the size of the glistening zone on the altimetry are discussed and analyzed at the same time. Finally, we calculate the sea surface height based on the simulated GNSS data within the whole day and verify the sea surface height errors according to the satellite elevation angles. The results show that the sea surface height can reach the precision of 6 cm for elevation angles of 55° to 90°, and the theoretical error and the calculated error are in good agreement.     

红外和微波辐射计反演海表面温度的比较

介绍了红外辐射计和微波辐射计测量海表面温度的原理,分析了它们各自在反演海表面温度时的差异。在全球范围的海表面温度的遥感蛉测中,红外辐射计和微波辐射计的遥感精度受到多种因素影响。传感器本身的噪音、算法反演精度、传感器分辨率、搭载卫星的全球覆盖率等自身因素使辐射计的探测资料产生差别：大气状况、海面风速、测量海洋不同深度海水的表征温度等外界因子也同时影响着红外辐射计和微波辐射计的遥感精度。了解红外波段和微波波段的辐射计在各方面的优劣,有助于发挥各自特长,有效提高卫星监测海表面温度的精度。     

Seasonal variations of the surface currents in the Tsushima Strait

Seasonal variations of the surface currents in the Tsushima Strait were investigated by analyzing the monthly mean surface currents measured with HF radar. Several new features of the surface currents have been found. One notable feature is the large, complicated seasonal variation in the current structure in the eastern channel of the strait. For example, in the southeastern and northwestern regions of the channel, southwestward countercurrents are found in summer while southeastward acrossshore currents are found in autumn and winter. The wind-driven flow (Ekman flow) as well as surface geostrophic currents are responsible for these complicated variations of the surface currents. To quantify each variation of the flow and current, the wind-driven flow was calculated from the monthly wind (more precisely, the friction velocity) using the monthly speed factor and deflection angle estimated in our previous study, and the surface geostrophic currents were then estimated by subtracting the wind-driven flow from the measured surface currents. It was found that the acrossshore currents are the wind-driven flow, and that the surface geostrophic currents flow almost in the along-shore direction, indicating the validity of the decomposition of the surface velocity into the wind-driven flow and the geostrophic currents using the speed factor and deflection angle. A real-vector empirical orthogonal function (EOF) analysis of the surface geostrophic currents shows a pair of eddies in the lee of Tsushima and Iki Islands as the first mode, which indicates that the southwestward countercurrents in the eastern channel are formed primarily by the incoming Tsushima Warm Current.     

东海陆架北部表层细粒级沉积物的级配及意义

本文依据东海陆架北部 2 3个表层沉积物样品的粒度分析资料 ,就东海陆架北部表层细粒级沉积物的级配及意义进行了研究。结果表明 ,研究区表层沉积物中细粒级部分以 <0 .0 16 mm为优势粒级 ,可占到总细粒级沉积物的 75 %以上。济州岛西南泥质区以细于 0 .0 0 8mm粒级的沉积物占据优势 ,长江口泥质区则以 <0 .0 16 mm粒级的沉积物为主 ,两泥质区细粒级沉积物的级配很不相同