Numerical modeling of wind and waves for Typhoon Betty (8710)

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LAGFD-Ⅱ区域性海浪数值模式及其应用Ⅰ.海浪数值模式

给出了LAGFD-Ⅱ区域性海浪数值模式,详细地导出了波数空间中的复杂特征线方程。在模式中除了含有一般的各项源函数项之外,我们还给出了波、流相互作用源函数,并对非线性相互作用源函数作了一种简化处理,模式的数值计算取得了令人满意的结果。     

分析作用于小桩柱波力的谱方法

确定海浪对海上孤立建筑物作用力的特征是海工设计中应考虑的主要问題之一。 近年来,人们开始用谱方法分析海波力的统计特征。这个问题可归结为求两个高斯平稳过程通过两元非线性过滤器的畸变谱及输出过程的分布。 从这样的提法出发,本文以较一般的形式导出了波力谱与表面谱的关系,并利用厄米多项式的特性,给出了波力分布密度的表达式。它表明,在海波作用下。桩柱所受的力是一准高斯过程,据此可导出一些近似的统计关系。 为了叙述方便,我们的讨论仅限于一维波动情况。     

黄海冷水团热结构及其环流解析研究

本文从一般的流体动力学－热力学方程组出发，通过对历史资料的分析，确立了描述黄海冷水团热结构及其环流的非线性控制方程组，得出近似解析解。理论计算结果表明，夏季北黄海冷水团区域存在中心上升边缘下降的气旋式密度环流。     

Statistics of breaking waves and its applications to estimation of air-sea fluxes (I)--Theoretical models

Wave breaking statistics, such as the whitecap coverage and average volume of broken seawater, are evaluated in terms of wave parameters by use of wave breaking model (Yuan et al., 1988) taking the fifth order Stokes's wave as the analog of the original wave field. Based on the observed fact that breaking waves play an important role in the exchange of mass, momentum and energy between the atmosphere and the ocean, the influence of wave breaking on air-sea fluxes of heat and moisture is investigated. Theoretical expressions of bubble-volume flux and sea spray spectrum at the sea surface and models for bubble-induced and spray droplet-induced heat and moisture fluxes are established. This work can be taken as the basis for further understanding the mechanism of air-sea coupling and parameterization models.     

Statistics of breaking waves and its applications to estimation of air-sea fluxes (Ⅰ)——Theoretical models

Wave breaking statistics, such as the whitecap coverage and average volume of broken seawater, are evaluated in terms of wave parameters by use of wave breaking model (Yuan et al., 1988) taking the fifth order Stokes's wave as the analog of the original wave field. Based on the observed fact that breaking waves play an important role in the exchange of mass, momentum and energy between the atmosphere and the ocean, the influence of wave breaking on air-sea fluxes of heat and moisture is investigated. Theoretical expressions of bubble-volume flux and sea spray spectrum at the sea surface and models for bubble-induced and spray droplet-induced heat and moisture fluxes are established. This work can be taken as the basis for further understanding the mechanism of air-sea coupling and parameterization models.     

Numerical experiments of HAB inducement in Qingdao adjacent coastal area

A three-dimension ecological dynamic model was established to numerically study the relationship of HAB and environmental conditions.The numerical experiments showed that the growth of diatom,the dominant HAB specie,was mainly restricted by phosphate and silicate.If the concentrations of phosphate and silicate reach 17-25 μg/L and 300-375 μg/L respectively,the water is in a state of eutrophication.When phosphate and silicate up to 26-32 μg/L and 350-500 μg/L respectively,HAB could be induced.The major regions of HAB occurrence are Jiaozhou Bay mouth,coastal bays,and coastal area from Maidao to Shilaoren.To avoid HAB occurrence,concentration of phosphate and silicate should not exceed 17-20 μg/L and 300 μg/L as a whole.Reasonable control of pollutant discharge is a key point to prevent water eutrophication and HAB occurrence.     

Eigen solutions of internal waves over subcritical topography

Diapycnal mixing plays an important role in the ocean circulation.Internal waves are a kind of bridge relating the diapycnal mixing to external sources of mechanical energy.Difficulty in obtaining eigen solutions of internal waves over curved topography is a limitation for further theoretical study on the generation problem and scattering process.In this study,a kind of transform method is put forward to derive the eigen solutions of internal waves over subcritical topography in twodimensional and linear framework.The transform converts the curved topography in physical space to flat bottom in transform space while the governing equation of internal waves is still hyperbolic if proper transform function is selected.Thus,one can obtain eigen solutions of internal waves in the transform space.Several examples of transform functions,which convert the linear slope,the convex slope,and the concave slope to flat bottom,and the corresponding eigen solutions are illustrated.A method,using a polynomial to approximate the transform function and least squares method to estimate the undetermined coefficients in the polynomial,is introduced to calculate the approximate expression of the transform function for the given subcritical topography.     

Dynamical analysis of mesoscale eddy-induced ocean internal waves using linear theories

This study aims to explore generation mechanisms of the ocean internal wave using the dynamical analysis methods based on linear theories. Historical cruise measurements and recent synthetic aperture radar （SAR） observations of mesoscale eddies with diameter of several tens of kilometers to hundreds of kilometers show that the internal wave packets with wavelength of hundreds of meters to kilometer exist inside the mesoscale eddies. This coexistence phenomenon and inherent links between the two different scale processes are revealed in the solutions of governing equations and boundary conditions for the internal wave disturbance with a horizontally slowly variable amplitude in a cylindrical coordinate system. The theoretical solutions indicate that the instability of eddy current field provides the dynamical mechanism to internal wave generation. The derived dispersion relation indicates that the internal wave propagation is modified by the eddy current field structure. The energy equation of the internal waves clearly shows the internal wave energy increment comes from the eddy. The theoretical models are used to explain the observation of the mesoscale eddy-induced internal waves off the Norwegian coast. The two-dimensional waveform solution of the anticyclonic eddy-induced internal wave packet appears as ring-shaped curves, which contains the typical features of eddy stream lines. The comparison of theoretical solutions to the structure of the internal wave packets on SAR image shows a good agreement on the major features.     

Determination of geostrophic flow by applying the principle of minimum energy and the inverse method

This article gives a computing method to calculate the geostrophic current. The fact that kinetic energy of geostrophic motion and geostrophic potential energy reach minimum simultaneously. Fomins “principle of minimum kinetic energy” is equivalent to the principle of minimum geostrophic potential energy. We concluded that horizontal geostrophic velocities at different depths are along the same direction. Combining our method with C. Wunsch’s inverse method we can obtain the velocity components along and normal to the hydrographic sections. We used and analysed CTD and current meter data of “Experiment No. 3” exploration, December 1985–January 1986, in the west Pacific Ocean—Philippine area. Contribution No. 1513 from Institute of Oceanology, Academia Sinica.