| ZHANG Ting,SONG Jinbao,LI Shuang,YANG Liangui. 2016. The effects of wind-driven waves and ocean spray on the drag coefficient and near-surface wind profiles over the ocean. Acta Oceanologica Sinica, 35(11):79－85 |
| The effects of wind-driven waves and ocean spray on the drag coefficient and near-surface wind profiles over the ocean |
| 风浪和海洋飞沫对海表面拖曳系数和风廓线的影响 |
| Received:November 15, 2015 Revised:February 05, 2016 |
| DOI：10.1007/s13131-016-0950-6 |
| Key words:wind-driven waves Ekman theory marine atmosphere boundary layer spray droplets |
| 中文关键词: 风浪 艾克曼理论 海气边界层 海洋飞沫 |
| 基金项目: |
| Author Name | Affiliation | E-mail | | ZHANG Ting | Ocean College, Zhejiang University, Hangzhou 310000, China
School of Mathematical Science, Inner Mongolia University, Hohhot 010000, China | | | SONG Jinbao | Ocean College, Zhejiang University, Hangzhou 310000, China | songjb@zju.edu.cn | | LI Shuang | Ocean College, Zhejiang University, Hangzhou 310000, China | | | YANG Liangui | School of Mathematical Science, Inner Mongolia University, Hohhot 010000, China | |
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| Abstract: |
| By introducing a wave-induced component and a spray-induced component to the total stress, a mathematical model based on the Ekman theory is proposed to detail the influence of wind-driven waves and ocean spray on the momentum transport in a marine atmosphere boundary layer (MABL). An analytic solution of the modified Ekman model can be obtained. The effect of the wave-induced stress is evaluated by a wind wave spectrum and a wave growth rate. It is found that the wave-induced stress and spray stress have a small impact compared with the turbulent stress on the drag coefficient and the wind profiles for low-to-medium wind speed. The spray contribution to the surface stress should be much more taken into account than the winddriven waves when the wind speed reaches above 25 m/s through the action of a "spray stress". As a result, the drag coefficient starts to decrease with increasing wind speed for high wind speed. The effects of the winddriven waves and spray droplets on the near-surface wind profiles are illustrated for different wave ages, which indicates that the production of the spray droplets leads the wind velocity to increase in the MABL. The solutions are also compared with the existed field observational data. Illustrative examples and the comparisons between field observations and the theoretical solutions demonstrate that the spray stress has more significant effect on the marine atmosphere boundary layer in the condition of the high wind speed compared with wave-induced stress. |
| 中文摘要: |
| 基于埃克曼理论，本文将波致应力和飞沫应力引入到海-气边界层的界面应力中，来研究海表面风浪和海洋飞沫对海-气边界层动量交换的影响，并得到修改后的埃克曼模型的理论解。波致应力是由风浪谱和波增长函数估计，并得到在中低风速下，波致应力、飞沫应力与湍流应力相比，对海表面拖曳系数和风廓线的影响非常小。当风速高于25米/秒时，海洋飞沫通过飞沫应力对海-气界面应力的作用远高于波致应力，以至于波致应力可以忽略。海表面拖曳系数在高风速下，随着风速的增大而减小。通过采用风浪谱的不同波龄，得到海洋飞沫的产生会导致海-气边界层风速的增加。最后，理论解与现场的观察数据进行了对比。对比后的数据表明，在中高风速下，飞沫对海-气边界层的影响远大于表面风浪。 |
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