盛夏南海北部台风和热带低压登陆前、后的对比分析

盛夏南海北部台风与热带低压登陆前、后对比诊断分析表明，影响这两类热带低值系统发展的物理因子和过程为：涡度平流作用对二者在海上发展都不利；有利的大尺度环境流场造成的气旋性辐合、气压场作功以及积云对流活动造成的涡度、扰动动能、热量的积累是台风，低压发展的基本因子；台风发展以斜压转换过程明显，热带低压发展以正压转换过程为主。     

Efficiency of reduced-order, time-dependent adjoint data assimilation approaches

Applications of adjoint data assimilation, which is designed to bring an ocean circulation model into consistency with ocean observations, are computationally demanding. To improve the convergence rate of an optimization, reduced-order optimization methods that reduce the size of the control vector by projecting it onto a limited number of basis functions were suggested. In this paper, we show that such order reduction can indeed speed up the initial convergence rate of an assimilation effort in the eastern subtropical North Atlantic using in situ and satellite data as constraints. However, an improved performance of the optimization was only obtained with a hybrid approach where the optimization is started in a reduced subspace but is continued subsequently using the full control space. In such an experiment about 50% of the computational cost can be saved as compared to the optimization in the full control space. Although several order-reduction approaches seem feasible, the best result was obtained by projecting the control vector onto Empirical Orthogonal Functions (EOFs) computed from a set of adjusted control vectors estimated previously from an optimization using the same model configuration.     

不定积分变换法对二度体磁异常的研究Ⅰ-水平圆柱体、直立薄板的不定积分变换

作者从二度磁性体的磁异常公式出发,推导出各异常的不定积分变换结果,并由变换结果绘制不定积分变换的磁异常参量图.本文选取2种规则形态磁性体,在取不同空间几何参数的条件下,讨论它们不定积分变换后参量图的曲线变化规律,并总结其异常特征,而后将其与积分变换前的参量图对比进行磁异常讨论和效果分析.该方法能反映一些重要的地质信息,将有助于实际的磁异常解释.     

海洋环境监测系统动态集成框架研究

区域性／全国性的海洋环境监测系统需要集成许多已有业务化运行的海洋信息系统,并且要为成千上万的应用系统提供服务,迫切需要一个支持分布式异构环境的海洋监测信息及服务集成框架来指导系统的建设。论文提出的基于XML,Web Service,Ontology,等技术的集成框架包括集成总线及Adapter Setvice,元数据库及集成协调器与供二次开发的API及Web Service工具集。这一集成框架是开放的可扩充的,它实现了数据互操作,软件互操作与语义互操作,可以应用于大规模海洋监测系统的动态集成,并能有效利用网上丰富的涉海商业Web服务。     

Nonlinear Analysis of Nearshore Wave Height Variation Due to Shoaling

Wave formulae derived from the dispersion relation for cnoidal waves are used to find an analytical solution to the problem of nearshore wave height variation on a simple topography, i. e., with an incrementally constant slope. The solution accounts for shoaling, frictional dissipation and will be sufficiently accurate for practical purposes considering the simplified assumptions which are necessary for the treatment of this problem by any method.     

Wave Transformation and Breaking in Diagonal Opposing Current

- When waves propagate into diagonal opposing current from non-current area, not only the wave parameters but also the direction of wave propagation will change, that is, wave refraction will occur. The authors have calculated the changes of wave parameters, including wave refraction, by Linear Wave Theory, and have also done systematic study on wave transformation and breaking in opposing current by means of experimental analysis and theoretical calculation. In order to know the effect of wave refraction, computation is done in this paper about wave transformation and breaking on gentle slopes in diagonal opposing current.     

简正波耦合机理与(广义)射线-简正波转换

结合广义射线 简正波转换、声场强度干涉结构研究了简正波耦合机理。给出了 1种简正波前向耦合矩阵的近似表示形式 ;引入“介质虚像”技法和图解法 ,讨论了简正波耦合的直观物理图象。证明简正波耦合强弱由声场强度干涉结构和环境扰动所决定 ,并解释了一些文献中描述的现象。利用“介质虚像”技法 ,给出了时间反转镜技术原理的简明解释。     

具有小时滞的线性系统次优控制的无滞后转换法

该文研究线性时滞定常系统的次优控制问题。根据无滞后转换法的思想 ,先引入状态向量的增量 ,将其视为附加扰动输入 ,再利用微分方程的逐次逼近法 ,将既含有时滞项又含有超前项的两点边值问题化为既不含时滞项又不含超前项的两点边值问题族。然后 ,把第 N次逼近得到的控制律近似为系统的最优控制律 ,得到次优控制律。并用实例仿真验证了该算法的有效性。该方法可使小时滞系统的迭代次数大大减少 ,因此尤其适合于小时滞系统的次优控制。     

Near-shore swell estimation from a global wind-wave model: Spectral process,linear, and artificial neural network models

Estimation of swell conditions in coastal regions is important for a variety of public, government, and research applications. Driving a model of the near-shore wave transformation from an offshore global swell model such as NOAA WaveWatch3 is an economical means to arrive at swell size estimates at particular locations of interest. Recently, some work (e.g. Browne et al. [Browne, M., Strauss, D., Castelle, B., Blumenstein, M., Tomlinson, R., 2006. Local swell estimation and prediction from a global wind-wave model. IEEE Geoscience and Remote Sensing Letters 3 (4), 462–466.]) has examined an artificial neural network (ANN) based, empirical approach to wave estimation. Here, we provide a comprehensive evaluation of two data driven approaches to estimating waves near-shore (linear and ANN), and also contrast these with a more traditional spectral wave simulation model (SWAN). Performance was assessed on data gathered from a total of 17 near-shore locations, with heterogenous geography and bathymetry, around the continent of Australia over a 7 month period. It was found that the ANNs out-performed SWAN and the non-linear architecture consistently out-performed the linear method. Variability in performance and differential performance with regard to geographical location could largely be explained in terms of the underlying complexity of the local wave transformation.