doi:  10.3878/j.issn.1006-9895.1803.17288
浪花和飞沫水滴在海面大风边界层中的垂直传输

Vertical Transport of Sea Spray and Spume Droplets in High-Wind Marine Atmospheric Boundary Layer
摘要点击 356  全文点击 314  投稿时间:2017-11-24  
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基金:  国家自然科学基金项目41630530,中国科学院前沿科学重点研究项目QYZDY-SSW-DQC002
中文关键词:  海盐气溶胶  重粒子  海上大气边界层  相干阵风扰动  上扬率  数值模式
英文关键词:  Sea salt aerosol  Heavy particle  Marine atmospheric boundary layer  Coherent gusty wind disturbance  Upwelling fraction  Numerical simulation
        
作者中文名作者英文名单位
曾庆存ZENG Qingcun中国科学院大气物理研究所, 北京 100029
程雪玲CHENG Xueling中国科学院大气物理研究所, 北京 100029
吴琳WU Lin中国科学院大气物理研究所, 北京 100029
引用:曾庆存,程雪玲,吴琳.2018.浪花和飞沫水滴在海面大风边界层中的垂直传输[J].大气科学,42(3):448-462,doi:10.3878/j.issn.1006-9895.1803.17288.
Citation:ZENG Qingcun,CHENG Xueling,WU Lin.2018.Vertical Transport of Sea Spray and Spume Droplets in High-Wind Marine Atmospheric Boundary Layer[J].Chinese Journal of Atmospheric Sciences (in Chinese),42(3):448-462,doi:10.3878/j.issn.1006-9895.1803.17288.
中文摘要:
      对我们在南海海域建立的大气边界层观测站的资料进行分析表明,在冷涌和热带气旋(包括强台风)过境的大风期间,在边界层底层10 min平均的水平风速u基本不随高度而变,甚至大都伴随有明显的上升气流w。而且风场脉动中含有强相干性的阵风扰动(vg,频率位于1/60~1/600 Hz频段),以及近于随机性的高频湍流脉动(vt,频率大于1/60 Hz),它们的特性以及w都可以很好地用水平风速u来参数化表示。取实测的(uw)和脉动v'=vg+vt,或取实测的u与参数化的vgvtw,应用拉格朗日随机模式作数值模拟,结果表明:由破头浪发射出来的浪花和飞沫水滴(半径rp为10~500 μm)有相当大的一部分可以飞离大气底层而进入100 m高以上的大气中,继而对进入大气中的海盐气溶胶通量有重要贡献,不可以被忽略。在水滴的垂直传输过程中,阵风扰动起了极重要的作用,而在w>0且较显著时w更起重要作用。我们对上扬率(可上升至100 m以上高度的水滴数与由海面发射出的水滴数之比)作出了初步的参数化公式,有很高的精度,主要的参量是无量纲量u2/(rqg),其中rpg分别是水滴半径和重力加速度。
Abstract:
      Through analyzing the observational data obtained during high-wind conditions over the South China Sea, our results have shown that:(a) The 10-min average horizontal wind speed u is almost independent of height; (b) the 10-min average vertical velocity w is almost always positive; (c) there exists strong coherent gusty wind with low-frequency (vg, between 1/600 Hz and 1/60 Hz), and nearly random and isotropic turbulent fluctuations with high-frequency (vt, larger than 1/60 Hz). The vertical velocity w and the characteristics of the gusty wind and turbulence can be well parameterized through the horizontal wind speed u. Using the observations of (u,w) and the parameterized gusty wind and turbulence, the Lagrangian stochastic model is implemented to study and simulate vertical transport of spume droplets. The results show that a quite high proportion of spray and spume droplets (the radius is between 10 and 500 μm) teared from the breaking waves can reach the 100 m height in ABL (Atmospheric Boundary Layer) and contribute to the sea salt aerosol flux. The coherent gusty wind during high winds plays an important role in the vertical transport of droplets. Besides, we also parameterize the uplifting fraction of spume droplets that can reach the 100 m height in the ABL by using a nondimensional factor u2/(rqg), where rp is the radius of droplet and g is the gravitational acceleration.
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