南京仙林地区大气边界层结构及其对空气污染的影响

发布时间：2017-12-27 10:08

本文关键词：南京仙林地区大气边界层结构及其对空气污染的影响　出处：《南京大学》2017年硕士论文　论文类型：学位论文

【摘要】：大气边界层是指对流层下部,直接受地面影响的大气层。湍流运动是边界层的主要特征,大气边界层内复杂的气象条件变化影响了整个大气的演变过程,对污染物的扩散和清除,对全球气候的稳定与变迁都有着极为重要的影响。探索南京仙林地区大气边界层结构及其对空气污染的影响,有助于深入认识该地区空气污染特征及演变规律,对于有效制定污染防治对策具有重要的意义。本文采用系留探空仪(ADAS)对该地区进行了两期探空观测实验,分别为:2013年12月26日～2014年01月10日(共15天)、2014年6月6日～2014年6月24日(共19天)。在此基础上,开展以下三个方面的研究工作:(1)通过分析观测到的风、温、湿、压等气象要素随高度的分布数据,研究得到该地区、不同时间气象要素垂直廓线特征以及逆温、大气混合层等边界层结构特征;(2)结合大尺度气象资料(地面天气图与高空环流形势),研究宏观气象条件对边界层结构的影响;(3)结合同期的大气污染物浓度数据,分析边界层结构对主要大气污染物(PM2.5、S02、NOx以及O3)浓度的影响。主要结论如下:(1)仙林地区夏季平均混合层高度为1200m,冬季平均混合层高度700m,夏季明显高于冬季;逆温层主要发生在夜间,多数为接地逆温,冬季接地逆温平均厚度为107.5m,逆温强度平均为1.14℃/100m,而夏季接地逆温平均厚度为190.48m,逆温强度平均为0.7℃/100m,说明南京仙林地区冬季多为强而低的接地逆温,夏季多为弱而高的接地逆温。(2)仙林地区冬季多数由均压场与高压控制,均压场控制下平均混合层高度400m,高压控制下平均混合层高度为825m,而冬季在冷性高压系统缓慢移动中,边界层结构稳定,混合层高度较低;夏季主要为副热带高压控制与均压场控制,副高控制下平均混合层高度为950m,均压场控制下平均混合层高度为1000m。在台风外围下沉气流控制下边界层结构变化迅速,但是在低压槽类型控制下边界层混合层高度偏低,且相对湿度较大,风速变化较大。(3)空气污染物地面浓度与混合层高度在冬季表现出较好的反相关关系,即污染物浓度变化与边界层结构变化趋于同步;但在夏季,这种反相关性较弱。这可能是因为夏季气象条件变化较快,边界层内水平扩散作用明显,从而削弱了这种相关性。边界层的日变化对不同污染物的地面浓度表现出不同的影响特征。对SO2来说,由于多为高架点源,夜间容易在高空形成高浓度区,当早晨混合层高度发展至高空烟流高度时,高浓度的SO2被迅速带至地面,在10:00左右形成一个峰值。对NO2来说,主要为移动排放源,受边界层结构变化影响,垂直扩散效果较好,因此NO2浓度与混合层高度有较好的反相关关系,14:00左右达到浓度低值。对于O3来说,受太阳辐射影响明显,午后14:00左右出现浓度峰值。
[Abstract]:The atmospheric boundary layer is the atmosphere of the lower troposphere, which is directly affected by the ground. Turbulent motion is the main feature of the boundary layer. The complex meteorological conditions in the atmospheric boundary layer affect the whole atmospheric evolution process. It has a very important impact on the diffusion and removal of pollutants and the stability and change of global climate. To explore the structure of atmospheric boundary layer of Nanjing Xianlin area and its influence on air pollution, it is helpful to know the characteristics of air pollution in the region and the evolution of the law, to develop effective pollution control measures has important significance. In this paper, two phase sounding observation experiments were carried out in the area by means of mooring sonde (ADAS). They were: December 26, 2013 to 2014 01, 10 (15 days), and June 6, 2014 to June 24, 2014 (19 days). On this basis, to carry out research work in the following three aspects: (1) through the analysis of the observed wind, temperature, humidity, pressure and other meteorological factors with the distribution of height data, study characteristics of the region and different time characteristics of meteorological elements and temperature inversion, vertical profiles of atmospheric mixed layer and boundary layer structure; (2) with large scale meteorological data (surface weather chart and the upper air circulation situation), macro research on the meteorological conditions on the influence of boundary layer structure; (3) combined with the atmospheric pollutant concentration data for the same period, analysis of the structure of the boundary layer on the main atmospheric pollutants (PM2.5, S02, NOx and O3) concentration. The main conclusions are as follows: (1) Xianlin area summer average mixed layer height is 1200m, the average winter mixed layer height 700m, significantly higher in summer than in winter; the inversion layer mainly occurs at night, most of the ground temperature inversion, ground temperature inversion the average thickness is 107.5m in winter, the average intensity of inversion /100m 1.14 degrees, while in summer the ground inversion of the average thickness is 190.48m, the average intensity of inversion is 0.7 DEG /100m, Nanjing Xianlin area in winter is strong and low ground temperature inversion, and summer for the weak and the high ground temperature inversion. (2) the winter Xianlin area mostly by the lower pressure and pressure control, uniform pressure field under the control of the average mixed layer height 400m, the average pressure under the control of the mixed layer height is 825m, and the winter in the cold high pressure system moved slowly, the stability of the boundary layer structure, the mixed layer height is low; the main summer subtropical high control with the lower pressure, under the control of subtropical high average mixed layer height is 950m, uniform pressure field under the control of the average mixed layer height is 1000m. The structure of the boundary layer changes rapidly under the control of the external subsidence of the typhoon, but under the control of the low pressure trough type, the mixing layer height of the boundary layer is low, and the relative humidity is relatively large, and the wind speed varies greatly. (3) there is a good inverse correlation between the surface concentration of air pollutants and the height of mixed layer in winter. That is, the change of pollutant concentration is synchronous with the change of boundary layer structure, but this correlation is weaker in summer. This may be due to the rapid changes in the weather conditions in summer and the obvious horizontal diffusion in the boundary layer, which weaken the correlation. The diurnal variation of the boundary layer has a different influence on the ground concentration of different pollutants. For SO2, because most of them are elevated point sources, it is easy to form high concentration area at high altitude at night. When the height of mixed layer develops to the height of high altitude in the morning, the high concentration of SO2 is brought to the ground quickly, forming a peak at about 10:00. For NO2, the main source of mobile emissions is affected by the change of the boundary layer structure, and the vertical diffusion effect is better. Therefore, the NO2 concentration has a good inverse correlation with the height of the mixing layer, reaching the low concentration around 14:00. For O3, the influence of solar radiation is obvious, and the peak of concentration at around 14:00 in the afternoon.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X51

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