兰州大学机构库 >大气科学学院
西部典型城市臭氧污染特征及其成因研究
Alternative TitleCharacteristics and Causes of Ozone Pollution in City in Western China
王劲博
Thesis Advisor王金艳
2019-05-30
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name学士
Degree Discipline大气科学
Keyword兰州 臭氧 时空变化规律 区域输送 光化学 STE过程
Abstract本文探讨了兰州地区臭氧污染特征、成因和影响因素。利用兰州地区2013-2018年五个站点臭氧及其前体物监测资料、2017年地面气象站观测资料、再分析资料和卫星遥感资料,利用统计分析、与其他城市横向对比、分类讨论、气流后向轨迹聚类、个例分析等方法,了解了兰州近几年臭氧污染不同时间和区域尺度的时空变化特征,了解了兰州地区臭氧的传输特征,综合分析了臭氧污染最严重的夏季气象条件、化学过程、垂直输送、大气动力与热力过程对该地区臭氧时空分布的影响。本文得到的最重要的结论如下:兰州地区臭氧污染较为严重且有加重趋势,臭氧污染夏季最严重,冬季最轻;受太阳辐射的影响,城区测站在各季节臭氧日变化呈现单峰模式;西固工业区内对应着工业生产行为实际发生地的工厂区是兰州地区臭氧污染最严重的地区,该区域通过传输等作用对兰州地区的臭氧污染有重要影响。受工厂区影响,工业区站点和过渡区站点臭氧和总氧化物浓度上升速度快,受风的影响更大;而距离工厂区较远的市区站点,受传输的影响则较小;郊区NO浓度低对臭氧污染有不利影响,受其影响,郊区臭氧浓度夜间明显高于城区;夏季兰州地区不同类后向气流轨迹下臭氧污染受光化学生成和垂直方向传输的影响较大,但垂直方向传输及STE的影响存在不确定性;若存在强太阳辐射,而大气中又含有丰富的臭氧前体物时,便会发生强烈的光化学反应,生成大量臭氧,导致臭氧污染发生;对流层顶折叠和强烈热力作用引起的对流层顶抬升都可能引起STE过程,导致平流层高浓度臭氧向下输送到对流层,对流层上部的位涡增大,且呈现出“高臭氧低湿”的特点。对流层顶折叠发生时,在高空中有与锋生和气旋相联系的高空急流区和低压槽。
Other AbstractIn this paper, the characteristics, causes and influencing factors of ozone pollution in Lanzhou are researched. Based on the measurements of ozone and its precursors on several sites of geographical difference in Lanzhou from 2013 to 2018, the annual variation of ozone pollution in Lanzhou in recent years were analyzed, and then a more detailed study was carried out. I compare the ozone concentration and diurnal variation of downtown city with industrial areas in different seasons, as well as the transitional zone between them.I study the different characteristic of ozone pollution in suburb and in city. I also study the transport of ozone and its precursors by compare the ozone concentration and diurnal variation in days prevailing easterly with days not prevailing easterly. By means of arithmetic statistic mean method, calculating backward trajectory of airflow and clustering into four groups, using surface atmospheric chemical observation data, satellite remote sensing data and reanalysis data, the effects of meteorological conditions, chemical processes and vertical transportation on the spatial and temporal distribution of ozone in summer which ozone pollution is the most serious were comprehensively analyzed,and two fundamental influencing factors of ozone pollution in Lanzhou were found. On this basis, typical cases were selected to study how the fundamental factors affect ozone pollution in Lanzhou,explain how the precursor concentration or weather dynamics and conditions affect ozone pollution.The following conclusions are drawn :1)The ozone pollution in Lanzhou is aggravating. The ozone pollution is the most serious in summer and the lightest in winter. 2)The number of cars in Lanzhou is lower than Hangzhou, Changsha, Shanghai and other cities, but the annual average hourly concentration of O3 or NO2 is higher than these cities. 3)Due to the influence of solar radiation, the diurnal variation of ozone in urban stations presents a single peak pattern in each season. 4)The zone where lots of factories located in the industrial area is the most serious ozone pollution areas in Lanzhou,has an important impact on the other areas in Lanzhou through transmit and discharge pollutant. Influenced by regional precursor concentration, precursor and ozone transport, the concentration of ozone and total oxide in industrial and transitional zone near the factories rises faster than that in the downtown city in daytime, the peak concentration is larger than that in the downtown area and appears earlier, which is more affected by wind than that in the downtown area, while the downtown area are less affected by factories because distance is far,the O3 and OX peak concentration are low and appear late. 5)Ozone concentration in suburban area is significantly higher at night than that in urban area due to the low NO concentration in suburban area.Meanwhile, the diurnal variation of ozone concentration is smaller in suburban area.The total oxide concentration in suburban area is not much different from that in urban area at night, and is lower than that in urban area during daytime. 6)In summer, the backward trajectory in Lanzhou can be divided into four representative paths, one of which is from the northwest of Gansu Province,which the median peak ozone concentration is the highest.What the path is short indicates that the weather condition is relatively stable and the phenomenon of high temperature and low humidity is easy to occur. Under the influence of this kind of air mass, the average concentration of CO and NO2 in Lanzhou is higher, the 2 m temperature away from the ground is higher, and the boundary layer is also higher, so this kind of mass is greatly influenced by photochemistry formation and STE. 7)If there is strong solar radiation and the atmosphere is rich in ozone precursors , strong photochemical reactions will occur, leading to ozone pollution. 8)Tropopause folding can cause STE process, which leads to the downward transport of stratospheric high concentration ozone to the troposphere. The potential vorticity in the upper troposphere and the lower stratosphere increases significantly, the humidity is low and the ozone concentration is high in troposphere. When tropopause folding occurs, the upper-level jet and pressure trough associated with Frontogenesis and cyclone can be observed at high altitude. 9)Thermal effects, which is caused indirectly by strong solar radiation, will cause the rise of the top of the boundary layer and tropopause, leading to STE which makes the potential vorticity increasing in the upper and middle troposphere. In the process of STE, stratospheric high concentration ozone is transported downward to the troposphere.
Pages56
URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/338337
Collection大气科学学院
Affiliation大气科学学院
First Author AffilicationCollege of Atmospheric Sciences
Recommended Citation
GB/T 7714
王劲博. 西部典型城市臭氧污染特征及其成因研究[D]. 兰州. 兰州大学,2019.
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