【作者】 甄灿明；

【导师】 胡非；

【作者基本信息】 中国科学院研究生院（大气物理研究所） ， 大气物理与大气环境， 2007， 硕士

【摘要】 非均匀下垫面通常主要指地表非均匀,包括热力非均匀和动力非均匀,由于实际地表总是呈现出一定程度的非均匀性和复杂性,所以对于非均匀边界层的研究已经成为当今大气边界层研究领域的热点问题。本文利用由LAPC承担的国家自然科学基金重点项目“地表通量参数化与大气边界层过程的基础研究”(编号40233030)的野外实验所获得的小球探空资料,对白洋淀地区水、陆非均匀下垫面的边界层结构进行分析,得到的主要结论如下:1、观测期间两地的边界层具有大气边界层的基本特点,即两地的风、温、湿廓线都具有白天对流混合层和夜间稳定边界层的典型廓线的分布特点。白天岛上的边界层高度比陆地上的高,岛上白天可达2000 m,陆地可达1800 m,而且两地的边界层顶经常可以看到覆盖逆温。夜间由于辐射冷却,两地都有逆温、逆湿出现,而且许多情况下伴随逆温有低空急流的出现,急流的发展与逆温的生、消演变关系密切。2、两地都是夜间风速比白天大,但是无论昼、夜,岛上的风速比陆地上的要大,而且夜间两地风速差别更大,越靠近地面这种差别也越明显。观测期间,陆上盛行风为偏西南风,1600 m以上转为偏北风,岛上盛行风向为西北偏北风,1400 m以上转为偏南风。两地存在弱的局地环流,而且以南北方向的环流为主。3、岛上地面及其上空的温度都比对应陆地上的温度要高,其地面温度平均比陆地要约高2.5℃,1000 m以下日平均温度比陆地约高3.14℃,而且夜间比白天两地的温度差别大,观测高度内随高度增加这种差别也变大。4、陆上的比湿比岛上的要大的多,其1000 m以下日平均比岛上大约2.35 g?kg-1,而且白天比夜间两地的比湿差别大,越靠近地面差别也越大,到高空超过2000 m就差别很小了。岛上比湿日变化比陆地上的要大,而且其夜间比湿比白天的大,而陆地上则是白天的比夜间的要大。5、由于下垫面的不同,两地的逆温表现出不同的特征。总的说来,陆地上接地逆温出现多,300 m以下的逆温平均强度大,逆温发展中的爆发性特征比较明显;而岛上则悬浮逆温出现多,300 m以下的逆温平均厚度大。不过两地的多层逆温都出现频繁,而且300 m以下的逆温强度和逆温顶高都有一定的负相关性,伴随着逆温也经常都有逆湿出现等。更多还原

【Abstract】 Heterogeneous underlying surface, which generally means the inhomogeneities over the surfaces, includes mainly thermal and dynamic heterogeneities. Since real underlying surface is always heterogeneous and complex to some extent, the research about it has become the hot topic in the field of current Atmospheric Boundary Layer (ABL) research. The data, which obtained from the radiosondes carried by free balloon in the Baiyangdian Experiment, is used to analyse the structures of ABL over the land and the water surfaces. And some conclusions are drawn as follows:1. During the experiment, the ABL over the two surfaces both show the general characteristics of ABL. That is to say, profiles of wind, temperature and specific humidity all present the typical distribution formation as theirs both in Convective Boundary Layer (CBL) and in Nocturnal Boundary Layer (NBL). In daytime, the ABL over the water surface is deeper than that over the land. For the former, its height is about 2000 m, while for the latter, it is about 1800 m. At the same time, there are both capped inversions at the top of ABL over the two places. In nighttime, because of radiative cooling, inversions together with humidity inversions always appear. Besides, Low-Level Jet (LLJ), whose development is related close with the evolution process of inversion, also emerges sometimes in two places.2. Wind always gets stronger from day to night, while it blows faster over the water than over the land whenever, and the wind velocity difference between the two places is greater when it comes near to the surface or in night. During the experiment, the prevailing wind over the land is southwesterly, and it changes into northerly wind over 1600 m. While, over the water surface, it is northwest by north and changes into southerly wind over 1400 m. In addition, there exists a local circulation, but it is much weak and is mostly in north-south direction.3. Surface water temperature and the air temperature over the water surface are both higher than theirs of the land. The average surface water temperature is about 2.5℃ higher than that of the land surface, and the daily average temperature below 1000 m over the water surface is about 3.14℃higher than over the land. Furthermore, the temperature difference between the two places is greater in night than in day, and it also gets greater with the height within the observed height.4. Specific humidity over the land is larger than over the water, which daily average specific humidity below 1000 m of the former is about 2.35 g?kg-1 larger than the latter. Also the specific humidity difference between the two places is greater in day than in night or when it comes near to the surface, and it is very small when it gets the height about 2000 m. In addition, the diurnal variation of specific humidity over the water is greater than that over the land, and the specific humidity over the water is larger in night than in day, while for the land, on the contrary, it is larger in day than in night.5. Owing to different underlying surface, the inversions over the two places present different characteristics. In a word, over the land surface, surface inversions appear more frequently, and average intensity of inversions below 300 m is greater, and the characteristic of burst of inversions is more obvious. On the other hand, over the water surface, elevated inversions emerge more times, and average thickness of inversions below 300 m is larger. Meanwhile, for the two places, many-layer inversions both appear frequently, and there is both some a negative correlation between inversion intensity and its top height below 300 m, and humidity inversions also often happen together with the inversions.更多还原