香港地区臭氧时空变化特征及成因分析

发布时间：2019-02-23 21:38

【摘要】：本文基于香港地区2011—2014年不同站点臭氧及其前体物监测资料,运用多种统计分析方法、气流后向轨迹聚类分析以及个例分析,对香港城市上风向、城中、城市下风向以及高山站点观测结果进行对比,研究香港地区近年来臭氧在三维空间上的分布和时空变化特征,综合分析气象条件和化学过程对于该地区臭氧时空分布的影响。在水平空间结构上,本文对比了香港地区不同地理位置观测站的臭氧及总氧化物Ox的季节分布、日变化,并运用Hysplit模式计算香港多年后向气流轨迹进而进行聚类分析,对影响香港地区空气污染物分布的气团来源进行归类,同时解析每一类气团对香港臭氧以及臭氧前体物的时空分布的影响。香港地区全年臭氧呈现出秋季十月份最高、夏季七月份最低的季节分布,臭氧的日变化呈现出双峰模式,小高峰出现在凌晨四点左右,日高峰在下午三点至四点之间,而且城区站点的双峰时间间距小于市镇站点和郊区站点。影响香港的气团来源呈现显著性季节变化,夏季受南面海洋性气团影响较大而秋冬季节则多受北面中国内陆沿海过来的气团的影响。为进一步分析香港地区下风向站点即香港国际机场及其周边地区臭氧和总氧化物的变化特征和规律,揭示相关成因,本文选取了香港机场附近多个站点高浓度臭氧事件进行分析,同时利用位于海上的站点作为中国内地的珠三角地区进入香港气团的背景站,分析香港机场局地排放造成的影响以及排放特点,发现机场附近由飞机等交通工具排放的NOx中N02的比例很高,这与通常报道的城市中汽车引擎排放的NOx中以NO为主不同,因此本文推断机场站点不能作为香港主导风向下风向的代表性站点。同时本文通过个例分析研究了珠三角气团对于香港污染物中NO, NO2以及CO的贡献,并由此认为东涌站点受珠三角地区跨区域传输影响较大,作为香港下风向代表性站点也不合适,如需要研究香港城区对于下风向站点的影响,应该考虑选取别的站点作为代表。在垂直空间结构上,本文通过对比香港最高山大帽山山顶站与地面大气背景站塔门站的臭氧及Ox季节分布、日变化、年际差异,结合相关气象要素解析香港地区在空间垂直结构上的臭氧分布特征,通过高山站春、夏这两个季节的高浓度臭氧事件起因的分析,探讨大气边界层高度的变化、中尺度环流与西太平洋海面台风对于香港高山站臭氧分布的影响,研究发现香港臭氧的浓度年际差异与季风强弱年际差异紧密相关,气候系统的年际变化可通过影响长距离传输影响香港地区大气氧化性和臭氧的分布；夏季西太平洋台风可通过影响水平传输将中国内地臭氧前体物浓度较高的气团通过长距离传输到香港高空,给香港山区造成光化学污染事件。
[Abstract]:Based on the monitoring data of ozone and its precursors at different stations in Hong Kong from 2011 to 2014, this paper applies a variety of statistical analysis methods, gas flow backward trajectory cluster analysis and case study to analyze the wind direction in the city of Hong Kong. In this paper, the spatial and temporal distribution of ozone in Hong Kong is studied, and the influence of meteorological conditions and chemical processes on the spatial and temporal distribution of ozone in Hong Kong is analyzed. In terms of horizontal spatial structure, the seasonal distribution and diurnal variation of ozone and total oxide Ox at different geographical stations in Hong Kong are compared, and the Hysplit model is used to calculate the track of backward air flow in Hong Kong for many years, and then cluster analysis is carried out. The air mass sources affecting the distribution of air pollutants in Hong Kong are classified and the effects of each type of air mass on the spatial and temporal distribution of ozone and its precursors in Hong Kong are analyzed. Throughout the year, the ozone level in Hong Kong was the highest in October in autumn and the lowest in July. The diurnal variation of ozone showed a double-peak pattern, with a small peak around 4 am and a daily peak between 3: 00 p.m. and 4: 00 p.m. And the bimodal time interval of the urban site is smaller than that of the town site and the suburban site. The sources of air mass in Hong Kong show significant seasonal changes. The sea air mass in summer is more affected by oceanic air mass in the south, while the autumn and winter seasons are mostly affected by the air masses from the inland coastal areas in the north of China. In order to further analyze the variation characteristics and laws of ozone and total oxides at the downwind direction station in Hong Kong, that is, the Hong Kong International Airport and its surrounding areas, and to reveal the relevant causes, This paper selects several stations near the Hong Kong Airport to analyze the high concentration ozone events, and uses the offshore stations as the background stations for the Pearl River Delta region in the mainland of China to enter Hong Kong air mass. Based on an analysis of the impact of local emissions from the Hong Kong Airport and the emission characteristics, it is found that the proportion of N02 in NOx emitted by aircraft and other vehicles near the airport is very high, which is different from the fact that NO is the main source of NOx emitted by automobile engines in cities. Therefore, this paper inferred that the airport station is not representative of the leading wind direction in Hong Kong. At the same time, the contribution of air mass in the Pearl River Delta to NO, NO2 and CO in Hong Kong is analyzed through an example, and it is concluded that the Tung Chung Station is greatly affected by the transregional transmission in the Pearl River Delta region. As a representative site of downwind direction in Hong Kong, if it is necessary to study the impact of Hong Kong urban area on the downwind site, other sites should be considered as the representative. In terms of vertical spatial structure, this paper compares the seasonal distribution of ozone and Ox between Tai Mo Shan Peak Station, the highest mountain in Hong Kong, and Tap Mun Station, the ground atmosphere background station, diurnal variation and interannual difference. Combined with the related meteorological elements to analyze the spatial vertical structure of ozone distribution in Hong Kong, and through the analysis of the causes of high concentration ozone events in spring and summer, the variation of atmospheric boundary layer height is discussed. The influence of mesoscale circulation and typhoon in the western Pacific on the ozone distribution in Hong Kong alpine station is studied. It is found that the interannual variation of ozone concentration in Hong Kong is closely related to the interannual variation of monsoon intensity. The interannual variability of the climate system can affect the atmospheric oxidation and ozone distribution in Hong Kong by influencing long-range transport; In summer, a typhoon in the western Pacific Ocean can transport the air mass with high ozone precursor concentration in the mainland of China to the high altitude of Hong Kong over a long distance through the influence horizontal transport, resulting in photochemical pollution events in the hilly areas of Hong Kong.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X515

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