海洋飞沫对海—气相互作用参数化影响的研究

发布时间：2018-05-13 22:43

本文选题：海洋飞沫 + 拖曳系数　；参考：《浙江大学》2016年硕士论文

【摘要】：随着人类对台风研究的不断深入,高风速下海洋飞沫的生成及其对海-气相互作用的影响越来越被广大学者所关注。飞沫的存在改变了海-气界面的组成状态,在海面形成水滴蒸发层,进而影响海-气之间的动量通量和热通量。研究并准确地参数化海洋飞沫对海-气相互作用的影响,对提高台风预报的准确性和海上平台的设计建造水平起着重要作用。本文基于已有的观测资料和研究成果,对海洋飞沫的生成机制进行探讨,并运用大涡模拟方法对海洋飞沫的生成进行数值模拟。通过数据分析发现：海洋飞沫生成以后以有效波高为中心向四周扩散,并沿垂向大致呈正态分布；随着风速的增大,生成的飞沫数量逐渐增多,但在垂向的变化趋势并没有改变。为了更好地分析影响飞沫生成的因素,本文在对Fairall实测数据分析的基础上,结合现有方案,对飞沫生成函数进行进一步考量和改进。综合考虑了风速和波浪状态的影响,并根据飞沫生成机制,扩大飞沫参数化范围,得到了新的飞沫生成函数,其半径覆盖范围更大,变化趋势和数量级都与观测数据更加吻合。本文还就飞沫对于台风的影响展开了讨论。飞沫的存在改变了海-气界面的接触状态,尤其在高风速下,生成的飞沫的数量以及飞沫层的厚度都达到了一定的程度,改变了海-气之间的摩擦状态,使得在高风速下,拖曳系数不仅不会持续增加,反而有逐渐减小的趋势。飞沫的存在增大了海-气之间热通量的交换面积,在一定程度上带来了感热和潜热通量的改变及其在总热通量中所占比例的变化,从而使得焓交换系数持续增加。焓交换系数和拖曳系数的比值随着风速的增大,增长率逐渐上升,这也是台风形成的必要条件。
[Abstract]:With the development of typhoon research, more and more scholars pay attention to the formation of ocean droplets under high wind speed and its influence on air-sea interaction. The presence of droplets changes the composition of the air-sea interface and forms a droplet evaporation layer on the sea surface, which in turn affects the momentum flux and heat flux between the sea and air. To study and accurately parameterize the influence of ocean droplets on the air-sea interaction plays an important role in improving the accuracy of typhoon prediction and the level of design and construction of offshore platforms. Based on the existing observation data and research results, the mechanism of droplet formation is discussed in this paper, and the large eddy simulation method is used to simulate the formation of ocean droplets. Through the analysis of data, it is found that after the formation of ocean droplets, the effective wave height is taken as the center of diffusion, and the vertical distribution is approximately normal, and with the increase of wind speed, the amount of droplets generated increases gradually. But the trend of vertical change has not changed. In order to better analyze the factors that affect the droplet formation, this paper further considers and improves the droplet generation function based on the analysis of the measured data of Fairall and the existing schemes. The influence of wind speed and wave state is considered synthetically. According to the mechanism of droplet formation, the parameterized range of droplet is enlarged, and a new droplet generating function is obtained, whose radius coverage is larger, and the variation trend and order of magnitude are more consistent with the observed data. The effect of droplets on typhoon is also discussed. The presence of droplets changes the contact state of the air-sea interface, especially at high wind speed, the amount of droplets generated and the thickness of the droplet layer reach a certain degree, which changes the frictional state between the sea and the air, resulting in high wind speed. The drag coefficient does not increase continuously, but decreases gradually. The existence of droplets increases the exchange area of heat flux between sea and air, and to some extent brings about the change of sensible heat flux and latent heat flux and the change of the proportion of total heat flux, which makes the enthalpy exchange coefficient increase continuously. The ratio of enthalpy exchange coefficient and drag coefficient increases gradually with the increase of wind speed, which is also a necessary condition for the formation of typhoon.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P732

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