| 摘要: |
| 在波面位移为均匀正态分布的假定下，导出了以海浪谱矩为参量的波面斜率分布函数。依此函数，利用极限波面斜率为波浪破碎判据导出依赖于海浪港四阶矩的白浪覆盖率的表示式。又通过Krylov谱和SMB海浪预报方法的经验公式，将海浪谱四阶矩代之以风要素，从而首次建立了一个依赖于风速和风区两者的半理论、半经验的海洋白浪覆盖率模式。此模式给出的结果与Monahan汇集的海洋白浪覆盖率测量数据符合颇佳。 |
| 关键词: 白浪覆盖率 波浪破碎判据 风速 风区 |
| DOI： |
| 分类号: |
| 基金项目:国家自然科学基金资助项目，49676277，49336070号 |
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| A STUDY ON OCEANIC WPHTECAP COVERAGE MODEL |
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YU Ding-yong,XU De-lun,LU Hong-min
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Engineering College, Ocean University of Qingdao, Qingdao, 266003
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| Abstract: |
| A simple model is analytically derived for estimating the spatial fraction of breaking sea surface at an instant of time, which is viewed as the whitecap coverage W. The derivation is based on a spatial homogeneous Gaussian wave field and using the limiting surface slope tan 30.37° = 0.586 (Longuet-Higgins et al, 1977) as a criterion of wave breaking. The resulting whitecap coverage is found depending on the fourth moment of spectrum, m4, and the critical threshold of surface slope. Expressing m4 in terms of the Neumann spectrum one arrives at a formula relating whitecap coverage W with wind speed U10 for fully developed sea state: W (U10) = 0.5Φ (-10.38U10-0.5), where Φ(z) is defined by Φ(z) = (See PDF file for detail). Expressing m4 in terms of the Krylov spectrum and employing the empirical relationships used in the SMB ocean wave prediction technique, one arrives at another formula relating W with both wind speed and fetch for fetch-limited sea state: W(F) = 0.5Φ(See PDF file for detail) where F represents the non-dimensional fetch: F = gx / U102. Comparison between these results and the field data of whitecap coverage collected by Monahan et al (1980) shows a rather good agreement. |
| Key words: Whitecap coverage, Criterion of wave breaking, Wind speed, Fetch |
