共查询到20条相似文献，搜索用时 937 毫秒
1.
海—气相互作用与海流、风暴潮 总被引：3，自引：4，他引：3
从方法论上说,除潮汐以外,通常在处理海洋动力学问题时,大多撇开海洋对大气的影响,强调大气对海洋的主导作用,把大气运动当作诱发海水运动的唯一原动力,视海面风场为给定条件,而后用经验或半经验公式算出海面风应力场,作为施加于海水的强迫力。因此,一个成功的海浪、海流或风暴潮的预报,除了具备反映海水运动的主要物理性能的数学模型外,还必须以客观的、准确的海面风场的数值计算和预报为前提。由于问题的复杂性,迄今为止似乎还不能说在实用上已经提供了海面风的一种足够精确的估算或预报方法。海上气象观测资料,尤其是测风资料的稀少,给海面风应力的实际计算带来不少困难。 相似文献
2.
一个简单的二维线性模式用于考查近海海洋对过境热带风暴的动力响应过程中的底坡度和底摩擦效应。选择了自东向西和向西后转向的两个模式风暴路径。数值试验结果表明，海底坡度与风暴引起的水位波动、风暴中心后部的尾流以及路径右侧后方面的涡旋密切相关。而底摩察是阻尼风暴潮和风暴流持续增长的重要因子。结果还表明，近海对风暴的强响应偏向于风暴轨迹的右侧，这与Ｃｈａｎｇ和Ａｎｔｈｅｓ（１９７８）对深海响应的研究结论是一 相似文献
3.
《Coastal Engineering》2006,53(2-3):289-301
Normal mode decomposition is shown to be a useful analysis methodology in the evaluation of storm tide and tsunami hazard at a coastal site. The prediction of the normal modes, the basin eigenmodes, is formulated as a Sturm–Liouville problem. Numerical solution follows transformation to a matrix eigenvalue problem. Numerical implementation issues are identified and resolved, and typical eigenmode solutions for spatially varied basins in one and two spatial dimensions are given. A spectral line plot is demonstrated as a suitable analysis summary for an historical storm tide or tsunami event. Prediction of the response amplitudes at the discrete eigenmodes is formulated and solved as a problem in multi-dimensional optimization. 相似文献
4.
Robert S. Pickart Michael A. Spall G.W.K. Moore Thomas J. Weingartner Rebecca A. Woodgate Knut Aagaard Koji Shimada 《Progress in Oceanography》2011,88(1-4):78-100
The spin up and relaxation of an autumn upwelling event on the Beaufort slope is investigated using a combination of oceanic and atmospheric data and numerical models. The event occurred in November 2002 and was driven by an Aleutian low storm. The wind field was strongly influenced by the pack-ice distribution, resulting in enhanced winds over the open water of the Chukchi Sea. Flow distortion due to the Brooks mountain range was also evident. Mooring observations east of Barrow Canyon show that the Beaufort shelfbreak jet reversed to the west under strong easterly winds, followed by upwelling of Atlantic Water onto the shelf. After the winds subsided a deep eastward jet of Atlantic Water developed, centered at 250 m depth. An idealized numerical model reproduces these results and suggests that the oceanic response to the local winds is modulated by a propagating signal from the western edge of the storm. The disparity in wave speeds between the sea surface height signal—traveling at the fast barotropic shelf wave speed—versus the interior density signal—traveling at the slow baroclinic wave speed—leads to the deep eastward jet. The broad-scale response to the storm over the Chukchi Sea is investigated using a regional numerical model. The strong gradient in windspeed at the ice edge results in convergence of the offshore Ekman transport, leading to the establishment of an anti-cyclonic gyre in the northern Chukchi Sea. Accordingly, the Chukchi shelfbreak jet accelerates to the east into the wind during the storm, and no upwelling occurs west of Barrow Canyon. Hence the storm response is fundamentally different on the Beaufort slope (upwelling) versus the Chukchi slope (no upwelling). The regional numerical model results are supported by additional mooring data in the Chukchi Sea. 相似文献
5.
ＮｕｍｅｒｉｃａｌｍｏｄｅｌｌｉｎｇｏｆｓｔｏｒｍｓｕｒｇｅｓｉｎｔｈｅＢｅｉｂｕＧｕｌｆｗｉｔｈＳＣＭ￥ＳｕｎＷｅｎｘｉｎ；ＬｕｏＹｉｙｏｎｇａｎｄＷａｎｇＪｉｎｇｙｏｎｇ（ＲｅｃｅｉｖｅｄＤｅｃｅｍｂｅｒ１５，１９９３；ａｃｃｅｐｔｅｄＭａｒｃｈ... 相似文献
6.
A. S. Vasilyev 《Physical Oceanography》1996,7(6):445-454
The paper considers the statement of the problem on quasi-stationary diagnosis of currents, temperature, salinity, and density
fields for multiply connected areas with fluid boundaries. The principles of self-similar parameterization over the vertical
axis are applied by introducing models for the vertical substance distribution, which have two regularly varying functions.
The problem is reduced to handling a set of Poisson equations, enabling the boundary conditions to be automatically determined
at the island shores. A scheme is presented for calculating current velocity components at an arbitrarily oriented transect.
Several examples of current velocity computation for the topographically complex oceanic areas are given which support the
data collectedin situ.
Translated by Vladimir A. Puchkin. 相似文献
7.
Regime shifts: Can ecological theory illuminate the mechanisms? 总被引：2，自引：0，他引：2
“Regime shifts” are considered here to be low-frequency, high-amplitude changes in oceanic conditions that may be especially pronounced in biological variables and propagate through several trophic levels. Three different types of regime shift (smooth, abrupt and discontinuous) are identified on the basis of different patterns in the relationship between the response of an ecosystem variable (usually biotic) and some external forcing or condition (control variable). The smooth regime shift is represented by a quasi-linear relationship between the response and control variables. The abrupt regime shift exhibits a nonlinear relationship between the response and control variables, and the discontinuous regime shift is characterized by the trajectory of the response variable differing when the forcing variable increases compared to when it decreases (i.e., the occurrence of alternative “stable” states). Most often, oceanic regime shifts are identified from time series of biotic variables (often commercial fish), but this approach does not allow the identification of discontinuous regime shifts. Recognizing discontinuous regime shifts is, however, particularly important as evidence from terrestrial and freshwater ecosystems suggests that such regime shifts may not be immediately reversible. Based on a review of various generic classes of mathematical models, we conclude that regime shifts arise from the interaction between population processes and external forcing variables. The shift between ecosystem states can be caused by gradual, cumulative changes in the forcing variable(s) or it can be triggered by acute disturbances, either anthropogenic or natural. A protocol for diagnosing the type of regime shift encountered is described and applied to a data set on Georges Bank haddock, from which it is concluded that a discontinuous regime shift in the abundance of haddock may have occurred. It is acknowledged that few, if any, marine data are available to confirm the occurrence of discontinuous regime shifts in the ocean. Nevertheless, we argue that there is good theoretical evidence for their occurrence as well as some anecdotal evidence from data collection campaigns and that the possibility of their occurrence should be recognized in the development of natural resource management strategies. 相似文献
8.
从三维浅海非线性流体动力学模型方程出发，使用进一步发展了的流速分解法，以７１０９号和８００７号台风为例，对北部湾的潮汐与风暴潮的耦合水位及流速进行了数值模拟．计算结果与实测资料基本相符．此外，还对北部湾风暴潮及天文潮的非线性效应进行了数值探讨．提出了有益的结论。 相似文献
9.
10.
东海风暴潮与天文潮的非线性相互作用 总被引：1，自引：0，他引：1
中国东海的风暴潮具有明显的周期性波动。凤暴潮除了决定于风应力和长波效应外,还受到天文潮与风暴潮相互作用的影响。本文利用一个二维数值模式对天文潮与风暴潮相互作用的水位进行了模拟。我们选取了8114号台风加以计算。计算结果与实测资料基本相符,由此说明水位曲线中的潮周期波动主要是由于天文潮与风暴潮之间的非线性相互作用所致。数值实验还表明,如果考虑到天文潮与风暴潮的相互作用可以显著改善水位的预报精度。 相似文献
11.
卫星遥感为大尺度海洋观测提供了一种可行方法。卫星资料应用于海洋初级生产力研究中最重要的是建立由海洋水色遥感资料得出的色素浓度计算初级生产力的合适算法。由于植物生理学方面的问题，建立一个合适的初级生产力算法有一定的困难。了解和确立水体中浮游植物的生理速率参数与分布结构动态是必要的。本文在分析水下光场和藻类光合作用光谱响应基础上，阐述了海洋初级生产力遥感中的生物－地理动力学问题。 相似文献
12.
全球热带风暴时空分布特点 总被引：2，自引：0，他引：2
对全球三大洋热带风暴的统计分析表明,全球热带风暴在时空分布上具有明显的统计特性.各海域热带风暴都具有季节集中性.在太平洋和印度洋,风暴发生频繁的时间在地理位置上有沿逆时针移动的分布.全球风暴总数在8月、9月份明显偏多,在4月、5月份明显偏少.北半球风暴扩展范围和分布密度大于南半球,并以东北太平洋和西北太平洋风暴分布密度为最大.各海域热带风暴发生频数在统计长度(33a)内都表现年际和10年际“振荡”,不同程度地存在2～3a,6～7a,11～12a及21～23a的重复性变化.较强的风暴,往往寿命也较长.在月份之间比较,风暴在多发月份,一般平均寿命较长,强度也较大;而在年度之间比较,风暴在多发年度,平均寿命却往往较短,强度也较小.风暴在大尺度环境中较好地沿反气旋路径向高纬度运动. 相似文献
13.
《中国海洋工程》2020,(1)
The numerical method of lines(MOLs) in coordination with the classical fourth-order Runge-Kutta(RK(4, 4))method is used to solve shallow water equations(SWEs) for foreseeing water levels owing to the nonlinear interaction of tide and surge accompanying with a storm along the coast of Bangladesh. The SWEs are developed by extending the body forces with tide generating forces(TGFs). Spatial variables of the SWEs along with the boundary conditions are approximated by means of finite difference technique on an Arakawa C-grid to attain a system of ordinary differential equations(ODEs) of initial valued in time, which are being solved with the aid of the RK(4, 4)method. Nested grid technique is adopted to solve coastal complexities closely with least computational cost. A stable tidal solution in the region of our choice is produced by applying the tidal forcing with the major tidal constituent M2(lunar semi-diurnal) along the southern open-sea boundary of the outer scheme. Numerical experimentations are carried out to simulate water levels generated by the cyclonic storm AILA along the coast of Bangladesh. The model simulated results are found to be in a reasonable agreement with the limited available reported data and observations. 相似文献
14.
Cao Guoao Shen Yilei
Dr.Professor Tongji University Shanghai
Shanghai College of Architectural Municipal Engineering Shanghai 《中国海洋工程》1991,(1)
In this paper, the responses of the interaction system of R.C. gravity single-leg platform to seismic excitation are mainly analysed. A set of nonlinear equations for the interaction system are established by using the wave, one is the soil-structure interaction and the other is the fluid-structure interaction. The seismic response of the interaction system is analysed for the influence of the asymmetric structure, fluid action, etc. with the input of seismic SH waves in any direction. The numerical results are given for a simple example. 相似文献
15.
一个高分辨率的长江口台风风暴潮数值预报模式及其应用 总被引：13，自引：1，他引：13
利用河口海岸海洋模式(ECOM-Si)建立了一个适用于长江口区风暴潮的数值预报模式.该模式采用对岸线有较好拟合能力的自然正交水平坐标系统和能分辨较复杂海底地形的垂直σ坐标系统.模式考虑了长江口径流量对风暴潮的影响,部分地考虑了天文潮和风暴潮非线性相互作用对风暴增水的影响.风暴潮预报的大气强迫场用模型气压场和模型风场.利用所建立的模式对长江口区台风风暴潮进行了8个个例模拟,模拟增水与实测增水的峰值相比较,平均绝对误差不足10cm.利用本研究建立的模式,就气象因子对风暴潮位的敏感性进行了数值试验.试验结果表明,台风中心气压降低(升高)20hPa可导致约100cm的风暴潮位升高(或降低).台风最大风速半径误差对台风增水的变化影响也较显著.试验还表明,长江径流量增加1倍(减半),可以造成风暴潮的平均增加25cm(减小13cm).天文潮位相变化对风暴增水的影响数值试验表明,当台风暴潮与天文潮在不同位相相互作用,可使风暴潮位最大增加达70cm或减小90cm. 相似文献
16.
采用潮流控制方程和湍封闭方程构建完整的三维浅海潮波定解方程组,建立涠洲岛附近海域的三维潮流数值模型来计算涠洲岛附近海域的潮流和潮位变化情况,采用大海域计算得出的调和常数值作为开边界的输入值,从潮位验证、潮流验证和流场的变化规律等多方面情况看,计算结果与实际监测符合良好,具有较高的精确度,模拟计算结果较真实地反映了涠洲岛附近海域的潮位变化和潮流运动状况.在潮流模拟验证正确的情况下,建立溢油预测模型,采用欧拉-拉格朗日追踪方法,进行油膜中心轨迹的预测,并预测了油膜漂移的扩展面积、扫海面积和残留量随时间的变化值. 相似文献
17.
上海沿岸天文潮与风暴潮非线性相互作用的数值研究 总被引：10，自引：0，他引：10
运用二维非线性风暴潮，天文潮和联合水位模型８次不同路径的热带气旋引起的上海地区天文潮与风暴潮的非线性相互作用进行了数值研究，讨论了天文潮气与风暴潮非线性相互作用引起的增水特征，分析了控制方程中各非线性项对天文潮与风暴晨线性相互作用引起水位变化的贡献，研究表明，考虑天文潮与风暴的非线性相互作用后，使风暴潮和水位的数值模拟结果得到了改善，非线性底摩擦在控制天文潮和风暴潮非线性相互作用中起重要的作用。而 相似文献
18.
强天气过程下海洋的响应是海洋环境预报的重要内容,它的研究对于防灾减灾、远洋运输、水产养殖等有积极的意义。本文中作者运用一个改进后具有模拟和预报能力的河口海洋模式ECOM-si,引入全强迫条件,对一个真实的强台风下的海洋响应进行了研究。模拟结果表明,海洋对台风过程有强烈的响应,强台风引起SST出现大幅降低,最大达5℃,其中大风抽吸和大风夹卷影响最大;大风引起的平流输送在实际情况中对海水温度、盐度的水平分布有重要影响:台风诱导海水上翻,会使得海洋的混合层明显加深,最大达20—30m;海洋在台风作用下,在上层海洋产生明显的气旋式流场,海面产生的明显下陷可达30cm,台风中心、气旋式流场中心和海面下陷中心三个位并不重合。同时在台风登陆位置附近产生风暴潮,最大增水可达0.8—1.0m,但沿海各地最大增水时间不相同。 相似文献
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20.
In the dynamic stability analysis of a caisson breakwater, most of current studies pay attention to the motion characteristics of caisson breakwaters under a single periodical breaking wave excitation. And in the lifetime stability analysis of caisson breakwater, it is assumed that the caisson breakwater suffers storm wave excitation once annually in the design lifetime. However, the number of annual severe storm occurrence is a random variable. In this paper, a series of random waves are generated by the Wen Sheng-chang wave spectrum, and the histories of successive and long-term random wave forces are built up by using the improved Goda wave force model. It is assumed that the number of annual severe storm occurrence is in the Poisson distribution over the 50-year design lifetime, and the history of random wave excitation is generated for each storm by the wave spectrum. The response histories of the caisson breakwater to the random waves over 50-year design lifetime are calculated and taken as a set of samples. On the basis of the Monte Carlo simulation technique, a large number of samples can be obtained, and the probability assessment of the safety of the breakwater during the complete design lifetime is obtained by statistical analysis of a large number of samples. Finally, the procedure of probability assessment of the breakwater safety is illustrated by an example. 相似文献