武汉市空气污染日的环流特征及大气边界层特征研究

发布时间：2018-06-02 16:15

本文选题：环流型 + 边界层　；参考：《南京信息工程大学》2015年硕士论文

【摘要】：城市的快速发展使得随之而来的大气环境问题备受关注。本文利用2004-2013年武汉市逐日污染物浓度资料、NCEP/NCAR再分析资料、L波段雷达资料和地面观测资料,采用Lambert-Jenkinson环流分型法对影响武汉地区的地面环流形势进行分类,统计分析武汉地区空气污染日的时空特征和边界层结构特点,通过WRF模式模拟空气污染生消过程中的局地气象条件变化,探讨边界层的变化特征和局地环流在其中所起的作用,综合分析大尺度环流背景和中小尺度局地气象条件对武汉地区空气污染形成的影响。利用Lamb-Jenkinson客观环流分型法,结合主观分析,对武汉地区大尺度环流背景场进行分析,探讨影响武汉地区的主要环流型及环流型与污染物浓度之间的关系。结果表明,影响武汉地区空气污染出现的主要环流型有反气旋型(A)、高压系统控制的偏东风型(AE)、偏东风型(E)、东南风型(SE)、弱低压型(C)及偏东北风型(NE),各季节较易出现污染的主要环流型不同。而中度及以上污染日的环流型主要为A、SE、E及AE型,受高压系统或偏东风影响时,高浓度污染较易出现。环流型对各种污染物浓度的影响程度存在差异。在对中小尺度局地气象条件的研究中,通过WRF模式模拟发现,由于武汉及周边地区三面环山,地形对流场影响明显。夜间山风与偏西北气流和偏东气流在武汉及周边地区耦合,形成气流汇聚带,使得污染物不断堆积,造成污染。局地环流和气流汇聚带随时间变化而变化,白天基本消失,各山谷风、偏北、偏东气流因强度的不同,形成的局地环流、气流汇聚带位置也有所差异。在较稳定大气边界层中,局地环流和气流汇聚带存在周期变化,有一定规律性。结合模式模拟结果与观测结果分析发现,武汉地区发生空气污染时,具有地域性特点。当发生污染时,大气层结较稳定,以贴地逆温为主,逆温强度较强,逆温层厚度较厚,混合层厚度较薄,湿度垂直层结呈上干下湿状态,中度以上污染时,到达一定高度后湿度随高度增加而增加,而轻度污染时,到达一定高度后,湿度随高度的增加而降低,地面有较小风速,甚至静风,有利于污染物不断堆积。
[Abstract]:With the rapid development of cities, the following problems of atmospheric environment have attracted much attention. Based on the daily pollutant concentration data of Wuhan from 2004 to 2013 and the L band radar data and ground observation data from NCEP / NCAR reanalysis data, the surface circulation situation affecting Wuhan area is classified by Lambert-Jenkinson circulation classification method. The temporal and spatial characteristics of air pollution days and the structural characteristics of the boundary layer in Wuhan are statistically analyzed. The variation of local meteorological conditions in the process of air pollution generation and elimination is simulated by the WRF model, and the variation characteristics of the boundary layer and the role of the local circulation in it are discussed. The influence of large scale circulation background and local meteorological conditions on the formation of air pollution in Wuhan is comprehensively analyzed. By using Lamb-Jenkinson objective circulation classification method and subjective analysis, the background field of large scale circulation in Wuhan area is analyzed, and the relationship between the main circulation pattern and the concentration of pollutants in Wuhan area is discussed. The results show that The main circulation patterns affecting air pollution in Wuhan area are anticyclonic type (Ae), high pressure system controlled easterly wind type (AEN), easterly wind type (E), easterly wind type (SEN), weak low pressure type (C) and northeasterly wind type (NE). The main circulation patterns which are liable to pollution in different seasons are different. However, the circulation patterns of moderate and above pollution days are mainly ACEE and AE, and the high concentration pollution is easy to occur under the influence of high pressure system or partial easterly wind. The effect of the circulation pattern on the concentration of various pollutants is different. In the study of local meteorological conditions in small and medium scale, WRF model simulation shows that the influence of topographic convection field is obvious due to the three sides surrounding the mountains in Wuhan and its surrounding areas. At night, the mountain wind coupled with the northwest and easterly airflow in Wuhan and its surrounding areas, forming a convergence zone of air flow, resulting in the accumulation of pollutants and resulting in pollution. The local circulation and air flow convergent zone changed with time and disappeared basically during the day. The local circulation and the position of the convergence zone were also different from each valley wind, northward and eastward air flow due to the different intensity of the local circulation and the airflow convergence zone. In the stable atmospheric boundary layer, the local circulation and the air flow converging zone have periodic variation and have certain regularity. The results of model simulation and observation show that the air pollution in Wuhan has regional characteristics. When the pollution occurs, the atmospheric stratification is more stable, mainly the ground temperature inversion, the inversion intensity is stronger, the thickness of the inversion layer is thicker, the thickness of the mixed layer is thinner, the vertical layer of humidity is dry and wet, and when the pollution is more than moderate, After reaching a certain height, the humidity increases with the increase of the height, but when the pollution reaches a certain height, the humidity decreases with the increase of the height, and there is small wind speed or even static wind on the ground, which is conducive to the accumulation of pollutants.
【学位授予单位】：南京信息工程大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X51;P434

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