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Role of wave breaking on the growth and decay of wind-waves and the sea surface flux of momentum, heat and gasses such as CO2.

波浪破碎对风浪的增长和衰减以及海面动量、热量和二氧化碳等气体通量的作用。

基本信息

批准号：
12304025
负责人：
MASUDA Akira
金额：
$ 26.87万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2003
项目状态：
已结题

项目摘要

1.[swell and wind-waves](1)Swell propagating with wind is known to suppress the growth of wind-waves. The suppression rate calculated based on the recently proposed hypothesis of Chen and Belcher was found to agree well with the result of the laboratory experiment, though careful verification is necessary. (2)A new term of swell dissipation was introduced to the operating MRI wave model. This term proved to much improve the accuracy of wave prediction off Hawaii in the Pacific, where most wave models have failed to predict the swell well so far.2.[wave breaking and water turbulence](1)The surface flow was observed in a thin layer that is about twice as thick as the significant wave height under strong wind and intense wave breaking. A new model of the vertical distribution of surface flow was proposed based on that measurement. (2)As regards the dissipation of wave energy, a simple model of wave breaking was incorporated into a numerical model for the direct numerical simulation of irr … More otational waves. That model yielded an estimate of energy dissipation that is compared favorably with laboratory experiments and wave prediction models.3.[whitecap]Wave breaking is detected by a visible phenomenon of "whitecap". Based on the observation under various wind-sea conditions, whitecap coverage was confirmed to increase rapidly with the third power of wind velocity. Also whitecap coverage was found relatively high for (1)unstable density stratification, (2)decaying waves, and (3)wind-waves unaffected by swell.4.[CO2 concentration and flux ](1)Daily variation and regional characteristics of atmospheric CO2 concentration was observed at Tsushima and Shikanoshima in the Eastern Tsushima Strait. (2)It was pointed out that correction due to the effect of vapor and temperature is necessary when eddy-correlation method is used to measure the CO2 flux in summer. (3)In a wind flume, CO2 flux across the water surface was measured accurately. Gas exchange velocity was found to depend not only on the wind velocity, but also on the fetch and a new empirical formula was proposed to express the fetch-dependence of the gas exchange velocity.5.[momentum flux : wave effect on the drag coefficient and roughness length of sea surface](1) A non-dimensional formula of the roughness of water surface waves that takes into account surface tension and viscosity was proposed based on laboratory experiments of high accuracy. (2)Momentum flux above the sea surface was measured at a sea station by simultaneous application of eddy-correlation, inertial dissipation and, profile methods in order to guarantee the reliability. Then a new comprehensive formula was proposed to explain the various previous formulas of roughness length that have seemed even contradictory with one another, in particular as regards the dependence on wind-waves. Less

1.[涌浪与风浪]〔1〕众所周知，随风传播的涌浪可以抑制风浪的增长。根据Chen和Belcher最近提出的假设计算出的抑制率与实验室实验的结果非常吻合，但还需要仔细验证。(2)在MRI手术波模型中引入了一个新的膨胀耗散项。事实证明，这一术语大大提高了太平洋夏威夷附近海浪预测的准确性，因为到目前为止，大多数海浪模型都不能很好地预测那里的涌浪。[破波与水湍流](1)在强风和强烈破波条件下，地表水流形成的薄层厚度约为有效波高的两倍。在此基础上，提出了一种新的地表水流垂直分布模型。(2)在波浪能量耗散方面，将一个简单的破波模型合并到一个数值模型中，直接数值模拟了irr和更多的动波。该模型得出的能量耗散估计与实验室实验和波浪预测模型相比是有利的。破波是由可见的“白浪”现象探测到的。根据不同风海条件下的观测，证实了白浪覆盖随着风速的三次幂迅速增大。此外，对于(1)不稳定的密度分层，(2)衰减波和(3)不受膨胀影响的风浪，发现白浪覆盖率相对较高。[CO2浓度与通量](1)观测了对马海峡东部对马岛和鹿之岛地区大气CO2浓度的日变化特征和区域特征。(2)指出利用涡相关法测量夏季CO2通量时，由于水汽和温度的影响，需要进行校正。(3)在风水槽中，准确测量了CO2在水面上的通量。结果表明，气体交换速度不仅与风速有关，而且与进气量有关，并提出了气体交换速度与进气量有关的经验公式。[动量通量：波浪对海面阻力系数和粗糙度长度的影响](1)在高精度室内实验的基础上，提出了考虑表面张力和黏度的水面波浪粗糙度的无量纲公式。(2)为保证测量的可靠性，在某海站采用涡流相关法、惯性耗散法和剖面法同时测量海面上的动量通量。然后，提出了一个新的综合公式来解释以前各种看似相互矛盾的粗糙度长度公式，特别是关于对风浪的依赖。少