A new form of generalized Boussinesq equations for varying water depth

A new set of equations of motion for wave propagation in water with varying depth is derived in this study. The equations expressed by the velocity potentials and the wave surface elevations include first-order non-linearity of waves and have the same dispersion characteristic to the extended Boussinesq equations. Compared to the extended Boussinesq equations, the equations have only two unknown scalars and do not contain spatial derivatives with an order higher than 2. The wave equations are solved by a finite element method. Fourth-order predictor–corrector method is applied in the time integration and a damping layer is applied at the open boundary for absorbing the outgoing waves. The model is applied to several examples of wave propagation in variable water depth. The computational results are compared with experimental data and other numerical results available in literature. The comparison demonstrates that the new form of the equations is capable of calculating wave transformation from relative deep water to shallow water.     

远区台风“三巴”对长江口波浪动力场的作用机制

针对远区台风对河口波浪动力场的影响问题,利用第三代波浪模式SWAN计算了远区台风"三巴"期间长江口波浪动力场分布,分析了陆架至河口区的波浪能量耗散和波致泥沙侵蚀的时空分布,发现波浪由外海向近岸传播过程中,波-波相互作用导致能量由高频向低频转换,周期和波长逐渐增大,近底层轨道流速增大,能量密度增高;阐明白帽破碎是维持深水区波浪能量平衡和限制波高成长的主要机制,底摩擦耗能和水深诱导的破碎耗能是长江口横沙东滩和崇明东滩邻近海域波高衰减的主要原因;提出波浪产生的底部切应力与相对水深有关,当波浪传播到浅水区时,波长和周期越大,波浪切应力越大。研究揭示了与河口相距数百公里的远区台风能够对长江口波浪动力场产生明显影响,河口水下三角洲前缘是最容易受到波浪侵蚀的区域,研究成果弥补了目前关于陆架远区台风对河口波浪动力场影响研究的不足,对深化认识远区台风对长江口动力环境、地貌演变、航运安全和滩涂保护等有重要科学意义。     

Full-range nonlinear analysis of fatigue behaviors of reinforced concrete structures by finite element method

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渤海、黄海、东海海面热量平衡的平均状况——Ⅰ.资料处理和计算方法

渤、黄、东海海面热量平衡状况对该海域海洋水文和中国气候有着重要的影响。我们对该海域热量平衡各分量的年平均和年变化进行了计算,并分别就资料处理和计算方法、年平均状况、年变化特征等几个方面进行了分析。本文作为该项研究的第一部分,讨论了所用的资料和计算公式,提出了在稳定温度层结条件下的交换系数的校正方法。     

266nm短脉冲激光对泥鳅鱼的胚胎效应

首次使用266nm激光脉冲对泥鳅受精卵进行辐照,引起畸变。辐照分别对全卵、只对胚盘、只对卵黄三种方式进行。对实验结果的分析说明266nm激光对泥鳅受精卵的作用是光化学作用,而不是光致热效应,可能引起DNA分子结构—碱基的变化。核质关系实验证明了细胞质对细脆发育过程有控制作用。     

海水中磷酸盐在固体粒子上阴离子交换作用 海水中磷酸盐-固体粒子相互作用的台阶型等温线

通过研究氯化钠溶液中磷酸盐在4种固体粒子（针铁矿、δ－氧化锰、伊利石和高岭石）上的交换等温线及钙对上述交换等温线的影响，发现磷酸盐液－固界面作用的台阶型等温线（2个台阶），可用分级离子／配位子交换等温式定量描述。钙能够促进磷酸盐在针铁矿和δ－氧化锰上的交换作用，其机理是交换在固体粒子上的钙再结合溶液中的磷酸盐，形成表面无机三元络合物。     

冬季中纬度海气相互作用与长江中下游汛期旱涝预测

中纬度海洋的热力状况对大气环流的维持和变化起着重要的作用,尤其在冬季。汛期的研究表明,冬季黑潮海域海表面水温(SST)与长江中下游和华北平原汛期降水有密切的关系(中国科学院大气物理研究所长期预报组,1978),夏季阿留申海域的SST异常与北太平洋上空大气环流场和后期秋季美国的气温和降水亦存在有意义的关系(Namias,1976)。赵永平(1986a;赵永平, McBean,1996)和Zhao and McBean(1989)曾用北太平洋海洋对大气加热场资料详细地分析了其时空分布特征,揭露了黑潮及邻近海域海洋异常加热对同期和后期半年至一年北半球大气环流的影响事实,并提出用海洋异常加热对同期和后期大气环流作用的反相性假说来进行解释。以上研究表明,冬季中纬度海洋异常加热与大气环流的异常和我国汛期旱涝之间存在一定的联系。 冬季黑潮和湾流海域是中纬度海洋的两个巨大热源,它们对同期和后期大气环流有重要影响。本文研究了冬季中纬度黑潮和湾流海域海洋异常加热对夏季副热带高压和中高纬度西风环流的影响,讨论了长江中下游汛期旱涝前期冬季和同期大气环流型。结果表明,冬季东亚和北美冷空气都强时,黑潮和湾流海域对大气异常多加热,夏季西太副热带高压、乌山和鄂海阻塞高压多趋减弱,中纬环流平直,形成长江中下游偏旱的环流形势；反之,西太副热带高压、乌山和鄂海阻塞高压多趋加强,中纬槽脊系统明显,形成长江中下游偏涝的环流场。本文还对可能的物理过程进行了讨论。     

黄海的风、潮混合特征及其对冷水团边界的影响

本文第一作者早在1985年就提出,潮混合效应控制着夏季黄海冷水团的边界及海面冷水分布(赵保仁,1985)。1987年又进一步通过水文调査资料和卫星图片给出了黄海周围的浅水陆架锋(或称潮汐锋)的分布及强锋区的跨锋断面中的温度、盐度和坏流结构特征,并指出夏季的黄海沿岸流在性质上属沿锋面运动的强流(赵保仁,1987a,b),而后又对黄海西部的陆架锋进行了一次专门调査(赵保仁等,1991)。此外,他还指出黄海的强温跃层的形成和转移现象也与潮混合现象密切相关(赵保仁,1989)。因此,研究潮混合现象对阐明发生在黄海的多水文物理现象都是至关重要的。 为深入了解黄海的潮混合特征,作者把渤海、黄海和东海作为一个整体完成了一次精度较高的潮汐、溯流数值计算,在潮汐、潮流的分布方面,揭示了前人尚未阐明的一些特征。本文根据这些数值结果,计算了近最大潮流流速和层化参数,阐明了渤海、黄海和东海的潮混合特征及其对降温期黄海冷水团分布变化的影响。此外,还用 Sim pson等人(1981)的能量模式计算了南黄海西部的风、潮混合效率。     

Study on short-range numerical forecasting of ocean current in the East China Sea——Ⅰ Basic problems of ocean current forecasting and structure of the models

Ocean current forecasting is still in explorative stage of study. In the study, we face some problems that have not been met before. The solving of these problems has become fundamental premise for realizing the ocean current forecasting. In the present paper are discussed in depth the physical essence for such basic problems as the predictability of ocean current, the predictable currents, the dynamical basis for studying respectively the tidal current and circulation, the necessity of boundary model, the models on regions with different scales and their link. The foundations and plans to solve the problems are demonstrated. Finally a set of operational numerical forecasting system for ocean current is proposed.     

Simulations of Annual Cycle of Phytoplankton Production and the Utilization of Nitrogen in the Yellow Sea

A nutrient dynamic model coupled with a 3D physical model has been developed to study the annual cycle of phytoplankton production in the Yellow Sea. The biological model involves interactions between inorganic nitrogen (nitrate and ammonium), phosphate and phytoplankton biomass. The model successfully reproduces the main features of phytoplankton-nutrient variation and dynamics of production. 1. The well-mixed coastal water is characterized by high primary production, as well as high new production. 2. In summer, the convergence of tidal front is an important hydrodynamic process, which contributes to high biomass at frontal areas. 3. The evolution of phytoplankton blooms and thermocline in the central region demonstrate that mixing is a dominant factor to the production in the Yellow Sea. In this simulation, nitrate- and ammonium-based productions are estimated regionally and temporally. The northern Yellow Sea is one of the highly ranked regions in the Yellow Sea for the capability of fixing carbon and nitrogen. The annual averaged f-ratio of 0.37 indicates that regenerated production prevails over the Yellow Sea. The result also shows that phosphate is the major nutrient, limiting phytoplankton growth throughout the year and it can be an indicator to predict the bloom magnitude. Finally, the relative roles of external nutrient sources have been evaluated, and benthic fluxes might play a significant role in compensating 54.6% of new nitrogen for new production consumption.