共查询到19条相似文献，搜索用时 187 毫秒
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微尺度滑动平均方法计算海浪谱奇阶矩的公式 总被引：2，自引：0，他引：2
Glazman提出了一种计算海浪谱高阶谱矩的微尺度平均方法,但是,他利用随机过程理论导出的计算偶阶矩的公式和参照偶阶矩结论定义的奇阶矩计算公式之间存在着内在的不一致性.本文在Glazman工作的基础上根据随机过程理论推导了“微尺度平均方法”计算奇阶谱矩的公式,纠正了他的错误.上述结论随即应用于讨论破碎对波面水质点水平速度分布的影响.通过破碎的加速度判据考虑了破碎对速度分布的限制,给出了未破碎波面上水质点水平速度的的统计分布的初步结果.该分布取决于谱宽度参数及白浪覆盖率的大小,当白浪覆盖率较大时明显偏离正态分布. 相似文献
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《中国海洋大学学报(自然科学版)》2016,(3)
白浪覆盖率法(白浪法)是被广泛应用的计算气溶胶粒子通量的方法,但是公式本身还存在一些问题,且其在低纬度海域的应用情况还未见报道。本文利用2012年8月25日—10月12日在中国南海走航实验观测的气溶胶粒子浓度数据,对Monahan等的白浪覆盖率-风速的公式进行了修正,并利用最小二乘法推导出单位白浪面积上次微米气溶胶产生通量与风速的关系。对半径小于0.3μm的粒子,通量的分布符合对数正态分布,通量的对数与风速呈幂函数关系。与高纬度海域的研究相比,中国南海飞沫气溶胶粒子的排放通量特征表现为较小粒子(r800.2μm)较其他海域偏高,而较大粒子略偏低。当风速在7~13m·s-1时,用新的源函数计算的通量与观测值保持较高的一致性。 相似文献
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不同海洋动力过程之间的相互作用决定了海洋系统内部的结构,外观表征上则反映了海洋动力要素的空间及剖面精细化分布与演变特征,海洋动力系统相互作用理论愈来愈成为支撑海洋耦合数值模式与数值预报发展的重要基础.不同于Reynolds尺度平均概念,基于局域平稳均匀统计意义下的集合平均可易于实现集合层级和系统划分.在此基础上提出了一... 相似文献
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Xu Delun Yu Dingyong Lu Hongmin Professor Physical Oceanography Laboratory Ocean University of Qindao Qingdao Associate Professor Engineering School Ocean University of Qindao Qingdao Senior Engineer Physical Oceanography Laboratory Ocean University of Qingdao Qingdao 《中国海洋工程》1998,(1)
Using the limit surface slope as a criterion of wave breaking,a simple model for estimatingthe spatial fraction of breaking surface of sea at an instant,which is regarded as the whitecap coverge inthis paper,is analytically derived from the probability density of surface slope based on Gaussianstatistics.The resulting fraction is found depending on the fourth moment of wave spectum,m_4,as well asthe critical threshold of surface slope.By expressing the fourth moment in terms of the Neumannspectrum,a formula linking the fraction and wind speed for fully developed sea states is obtianed.Anotherformula relating the fraction to both wind speed and fetch(or duration)is achieved by expressing m_4 interms of the Krylov spectrum and applying the empirical relationships used in the SMB ocean wave pre-dicting technique.A comparison between these results and the field data of whitecap coverage collected byMonahan and O＇Muircheartuigh shows an encouraging agreement. 相似文献
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波浪破碎是一个强非线性过程,破碎时产生的大量气泡在海面上表现为白冠,白冠覆盖率是刻画波浪破碎一个重要参数。研究表明,白冠覆盖率与海上风速、海浪状态和大气稳定度等多种海洋环境因素有关。综合前人的观测数据,本文给出了更为可靠的依赖风速的白冠覆盖率公式,发现海水温度越高,白冠覆盖率越大。提出了以波浪破碎耗散函数为参数的白冠覆盖率公式,同时发现波龄小于某个临界值时,白冠覆盖率随波龄增大,波龄大于临界值时,白冠覆盖率保持不变,该临界值随风速增大而减小。 相似文献
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Based on the nonlinear model of two-dimensional random sea waves, a statistical distribution of wave surface slope exact to the third order is derived by using the expansion of the characteristic function and direct calculations of each order moment. Based on the distribution of wave surface slope derived in this paper, a whitecap coverage is proposed by using the limit surface slope as a criterion of wave breaking. The whitecap coverage expressed by the model depends on three parameters which can be determined in principle by the linear wave spectrum and three kinds of wave-wave interaction. 相似文献
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More and more researches show that neither the critical downward acceleration nor the critical slope of water waves is a universal constant. On the contrary, they vary with particular wave conditions. This fact moders the models either for the probability of wave breaking B or for the whitecap coverage W based on these criteria difficult to apply. In this paper and the one which follows we seek to develop models for the prediction of both B and W based on the kinematical criterion. First, several joint probabihstic distribution functions (PDFs) of wave characteristics are derived, based on which the breaking properties B and W are estimated. The estimation is made on the assumption that a wave breaks ff the horizontal velocity of water particles at its crest exceeds the local wave celerity, and whitecapping occurs in regions of fluid where water particles travel faster than the waves. The consequent B and W depend on wave spectral moments of orders 0 to 4.Then the JONSWAP spectrum is used to represent the fetch-limited sea waves in deep water, so as to relate the probahility of wave breaking and the whitecap coverage with wind parameters. To this end, the time-averaging technique proposed by Glazman (1986) is applied to the estimation of the spectral moments involved, and furthermore, the theoretical models are compared with available observations collected from published literature. From the comparison, the averaging time scale is determined. The final models show that the probability of wave breaking as well as the whitecap coverage depends on the dimensionless fetch. The agreement between these models and the database is reasonable. 相似文献
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基于卫星数据改进计算白冠覆盖率的模型 总被引：2，自引：1，他引：1
本文基于白冠覆盖率的历史研究,总结了计算白冠覆盖率的参数化方案和海浪破碎统计模型,并分析比较其优缺点。通过结合基于卫星数据的参数化公式,利用最优拟合的方法,得到不同限制条件下模型中的系数Cen和n。通过分析考虑海浪破碎条件,确定了适用于一般海浪状况的系数值。通过比较白冠覆盖率的卫星数据和原始模型的模拟结果,可知改进后模型的结果更合理,同时与历史研究结论相符。文中还分析了从1998年到2008年十年平均的全球白冠覆盖率的季节性分布特征。在中高纬度海域,全年白冠覆盖率的值最大,而在低纬度和赤道海域,白冠覆盖率小于0.5%,全球白冠覆盖率的平均值大约为1% ~3%。北半球中高纬度海域的白冠覆盖率的季节性变化显著大于南半球。 相似文献
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The paper considers the effects of wave age and air stability on the whitecap coverage at sea. This is made by using the logarithmic mean wind velocity profile including a stability function as well as adopting a recent wave age dependent sea surface roughness formula. The results are valid for wind waves in local equilibrium with the steady wind. Examples of results demonstrate clear effects of wave age and air stability on the whitecap coverage. Comparisons are also made with field measurements by Sugihara et al. [Sugihara, Y., et al., 2007. Variation of whitecap coverage with wave-field conditions. J. Mar. Syst. 66, 47–60], representing unstable air stability conditions. Although the data basis is limited, the wave age independent Charnock sea roughness based predictions capture the main features of the observed whitecap coverage, suggesting a stronger dependence on air stability than on wave age in the data. 相似文献
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海浪破碎使得海面产生飞沫水滴,由于飞沫水滴的存在改变着大气和海洋之间的能量传输。飞沫生产函数一般认为是水滴初始半径和风速的函数,但海浪时刻存在于海-气界面,仅仅考虑海面风的作用,而忽略海浪的影响是不够完善的。白冠覆盖率是海浪破碎的重要特征参数,有研究者发现白冠覆盖率与海面风速和海浪均存在相关性。本文尝试从白冠覆盖率出发,构建飞沫水滴的生成函数参数化方案,将描述不同飞沫水滴半径的飞沫生成函数基于白冠覆盖率参数有机整合,然后结合白冠覆盖率和海浪状态的关系,利用实验室观测数据,分析不同海浪状态条件下海浪对飞沫生成函数的影响。研究结果表明,新的考虑波浪效应的飞沫生成函数可以合理地描述不同海浪状态条件下飞沫水滴的生成过程。 相似文献
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An analytically derived whitecap coverage model 总被引：3，自引：0，他引：3
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Dependence of Whitecap Coverage on Wind and Wind-Wave Properties 总被引：13，自引：0，他引：13