北京灰霾重污染过程典型案例剖析

发布时间：2018-05-14 01:19

本文选题：北京地区 + 灰霾　；参考：《山东师范大学》2017年硕士论文

【摘要】：近年来,随着北京城市规模的不断扩大,污染排放量不断增加,主要的大气污染排放总量远远超过了环境容量,但北京市地形结构较为特殊,不利于污染物的稀释扩散,因此近些年来灰霾天气出现的次数越来越多,影响程度也在逐步加大,给日常生活、交通运输和人体健康都带来了很大的不利影响。本文对2015~2016年度北京灰霾污染特征进行分析,并作出一年的后向气流轨迹进行聚类分析,由此挑选出典型的灰霾重污染过程,利用观测实验所得数据对典型案例进行剖析,分析其污染特征及污染成因,具体结果如下:(1)2015年9月至2016年8月北京灰霾发生小时数为3891小时,灰霾日数为190天。其中,11月灰霾日出现最多为27天,7月、12月次之均为23天,灰霾日出现最少的是2月,仅为6天。另外,各月干霾时发生频率均高于湿霾。研究期间月均AQI均超过50,AQI与PM2.5变化趋势基本一致,均呈现出2015年9月至2015年12月上升的趋势,到2016年1月、2月有所下降,然后再上升、下降、上升、下降的波浪式变化趋势。综上所述,研究期间北京的空气质量状况与气象学中霾的观测统计情况基本一致。(2)对北京市进行后向轨迹聚类分析,得到5类,并计算每类轨迹对应的PM 2.5平均浓度,其中来自内蒙古西部地区及河北、山东、河南交界地区的两类轨迹对北京的空气质量有较大的影响;来自北西北方向轨迹的气团最为清洁,为北京带来良好的天气;利用潜在污染源贡献法(PSCF)、轨迹浓度权重分析法(CWT)对北京的PM 2.5浓度进行分析,高值区主要集中在河北、山西及其周围地区,表明短距离传输是导致北京PM 2.5高浓度的主要原因。(3)本文别用气象学中的灰霾日和AQI作为两大参考指标挑选污染过程,对连续3天及以上空气质量指数大于100的灰霾日挑选为为灰霾重污染过程,共得到18个灰霾重污染过程,并结合后向轨迹模式挑选最具有代表性的污染过程7(2015年11月26日~12月2日,冬季采暖期)以及污染过程17(2016年7月2日~12日,夏季非采暖期)。(4)2015年11月26日~12月2日的典型污染过程7涉及整个中东部地区,大部分地区PM2.5日均浓度高于250ug?m-3,北京地区更是处于严重“爆表”状态,是一次大范围、长时间的污染天气过程。2016年7月2日~12日的典型污染过程17轻度污染涉及的地区范围较广,中度污染及上水平的污染主要涉及京津冀地区、济南以及河南等地区,出现中到重度污染,是一次小范围、长时间的污染天气过程。(5)冬季采暖期的污染过程期间70%的时段能见度低于2km,达重度霾污染级别。相对湿度最高达88.9%,促进了细颗粒物污染物的生成。污染期间风速较低,静风频率达18%,风向以西南风为主。夏季非采暖期的污染过程期间平均相对湿度为51.6%,能见度基本上维持在5Km左右,以轻微霾和轻度霾为主;风级主要为1级和2级水平,对应了0.3~3.3m/s的风速,风速相对较低,近地污染物稀释扩散能力较弱,并且风向以南风为主。(6)两次典型污染过程在垂向的光学特征分析中,均在污染严重期间出现消光物质,不同的是,冬季的污染过程是伴随着气象条件的转变以及边界层高度的升高,污染驱散,而夏季的污染过程是由于一场降雨将污染驱散。另外,在冬季的污染过程中,大气边界层高度与PM2.5有着明显的反比关系,且污染期间以稳定层结为主;而夏季的污染过程中,在严重污染期间大气边界层高度很低,大气层结属于稳定层结,在轻度污染期间,PM2.5浓度却与大气边界层高度的波动无明显相关关系,大气层结属于不稳定层结。
[Abstract]:In recent years, with the continuous expansion of urban scale in Beijing, the emission of pollution is increasing, the total emission of major air pollution is far more than the environmental capacity. However, the topography of Beijing is more special and is not conducive to the dilution and diffusion of pollutants. Therefore, the haze weather has become more and more frequent in recent years, and the degree of influence is gradually increasing. The characteristics of daily life, transportation and human health have been greatly adversely affected. In this paper, the characteristics of Beijing haze pollution in the year 2015~2016 are analyzed, and a year of cluster analysis of the back flow trajectory is made, and the typical haze heavy pollution process is selected, and the typical cases are analyzed by the data obtained from the observation experiment. The results are as follows: (1) the number of haze in Beijing from September 2015 to August 2016 is 3891 hours, and the number of haze days is 190 days. Among them, the haze days in November are up to 27 days, July and December are 23 days, and the least in the haze day is February and only 6 days. In addition, the frequency of haze in each month is all frequency Higher than the wet haze. During the study, the monthly average AQI was over 50, and the trend of AQI and PM2.5 was basically the same, showing a trend of rising from September 2015 to December 2015, in January 2016, in February, and then rising, decreasing, rising, and decreasing in wave style. The air quality of Beijing and the haze in meteorology during the study. The observational statistics are basically the same. (2) 5 types are obtained and the average concentration of PM 2.5 corresponding to each kind of trajectory is calculated, and the two kinds of trajectories from the west of Inner Mongolia and Hebei, Shandong and Henan have a great influence on the air quality of Beijing, and the gas from the northwestern northwest direction. The group is most clean and brings good weather for Beijing. Using the potential pollution source contribution method (PSCF), the locus concentration weight analysis (CWT) is used to analyze the PM 2.5 concentration in Beijing. The high value area is mainly concentrated in Hebei, Shanxi and its surrounding areas, which indicates that the short distance transmission is the main cause of the high concentration of the Beijing PM 2.5. (3) this article does not use the weather. The haze day and AQI were selected as the two major reference indexes to select the pollution process. The haze days of 3 days or more of the air mass index more than 100 were selected as the haze heavy pollution process, and 18 haze heavy pollution processes were obtained, and the most representative pollution process 7 (November 26, 2015, ~12 month, 2, winter, November 26, 2015) was selected in combination with the backward trajectory model. The season heating period) and the pollution process 17 (July 2, 2016 ~12 day, summer non heating period). (4) the typical pollution process of ~12 month 2 of November 26, 2015 is involved in the whole Middle East region. The average daily concentration of PM2.5 in most areas is higher than 250ug? M-3, and the Beijing region is in a serious "burst form" state, it is a large scale, long time pollution weather. The typical pollution process of ~12 day July 2nd,.2016, 17 mild pollution involving a wide range, moderate pollution and upper level of pollution mainly involved in the Beijing Tianjin Hebei region, Ji'nan and Henan and other areas, the emergence of moderate to severe pollution, is a small, long time pollution weather process. (5) during the winter heating period 70% of the pollution process. The visibility is lower than 2km, reaching the level of heavy haze pollution. The highest relative humidity reaches 88.9%, which promotes the formation of fine particulate matter. The wind speed is low, the wind velocity is 18%, the wind direction is west to the south wind. The average relative humidity is 51.6% during the non heating period in summer, and the visibility is basically around 5Km. Haze and light haze are the main factors; the wind level is mainly 1 and 2 levels, corresponding to the wind speed of 0.3~3.3m/s, the wind speed is relatively low, the dilution and diffusion capacity of the near ground pollutants is weak, and the wind direction is mainly south wind. (6) the two typical pollution processes in the vertical optical characteristics are all in the period of serious pollution, the different is winter. The pollution process is accompanied by the change of meteorological conditions and the elevation of the boundary layer, and the pollution is dispersed. In summer, the process of pollution is caused by the dispersal of the pollution. In the process of winter pollution, the height of the atmospheric boundary layer has an obvious inverse relation to the PM2.5, and the stable layer is the dominant layer during the pollution period, and the pollution in the summer is the same. During the process of serious pollution, the atmospheric boundary layer is very low, and the atmosphere is a stable layer. During the mild pollution, the concentration of PM2.5 has no significant correlation with the fluctuation of the atmospheric boundary layer, and the atmosphere is an unstable layer.

【学位授予单位】：山东师范大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X513

【参考文献】