气象因素和前体物对中国东部O3浓度分布的影响

Impact of meteorological factors and precursors on spatial distribution of ozone concentration in Eastern China

采用重心模型、空间自相关分析和地理探测器,研究了2016年中国东部O3浓度的时空变化规律,揭示了气象因素和前体物对中国东部O3浓度空间分布格局及其演变的影响.结果表明:(1)O3浓度变化可分为3个阶段:1~3月为低值上升阶段、4~9月为高值波动阶段、10~12月为低值下降阶段,O3污染主要发生在高值波动阶段,超标天数占全年的96.0%.(2)气象因素是影响O3年均浓度空间分布格局的主导因素,受降水、相对湿度南高北低和日照时数北高南低的影响,O3年均浓度总体呈北高南低的态势;前体物对O3年均浓度分布也有显著影响,是城市群核心城市形成局部O3污染中心的原因.(3)O3月均浓度分布格局经历了由北高南低到南高北低的演变过程,1~6月O3浓度总体重心和高值重心向北迁移,6月达到最北,北高南低的特征最强,环渤海地区成为O3污染最严重的区域;7~12月,O3浓度总体重心和高值重心向南迁移,12月达到最南,O3浓度分布格局演变为南高北低.3~9月雨季期间,O3浓度分布主要受降水和相对湿度的影响,其余时间主要受气温的影响.(4)前体物对O3浓度分布的影响主要通过气象条件实现,气温越高,光化学反应越强,前体物的正向影响力越大;气温越低,光化学反应越弱,NOx、CO、SO2等化学性质活跃的前体物对O3可能起消耗作用.

Based on the methods of gravity center model, spatial autocorrelation analysis and geographical detector, this paper studied the spatial and temporal distribution of ozone concentration in Eastern China in 2016, revealed the impact of meteorological factors and precursors on the spatial distribution and evolution of ozone concentration. The results showed that: 1) Average monthly concentration of ozone went through three phases in Eastern China in 2016, rising gradually from January to March before reaching a fluctuating stage from April to September, it came to a decreasing phrase later from October to December. Ozone pollution was mainly witnessed at the second phase, which contributed 96 percent of the yearly ozone pollution. 2) Mainly affected by meteorological factors, namely lower precipitation, lower relative humidity and longer sunshine duration in the northern part of Eastern China, the annual ozone concentration of northern part was higher than that of southern part in Eastern China in general. Beside, pollution centers in core cities of urban agglomerations generated because of precursors, which was a significant factor of the yearly average ozone concentration distribution. 3) Spatial distribution of ozone concentration went through a higher-in-the-north pattern to the higher-in-the-south pattern in 2016. The monthly gravity center of ozone concentration was moving to the north from January to June, reaching its northernmost point in June. The higher-in-the-north pattern was at its most significant phase at that time, the highest point of pollution level was reached in Bohai Rim region. Then it moved backward to south until December when the southernmost point was reached, during which the distribution pattern was transforming into the higher-in-the-south pattern. During rainy season(from March to September), the spatial distribution of ozone concentration was mainly impacted by precipitation and relative humidity compared with a major impact by temperature in the rest of months. 4) Precursors worked with meteorological factors. A stronger photoreaction, as a result of rising temperature, positively magnified the impact of precursors while the decreasing temperature weakened photoreaction, which, as a result, may promote ozone consumption.