粤港澳大湾区NO2污染的时空特征及影响因素分析

利用Aura卫星搭载的臭氧观测仪（OMI）反演的对流层NO₂柱密度数据，分析了自2005年以来粤港澳大湾区（GBA）对流层NO₂柱密度的空间分布特征、时间变化趋势及其影响因素.研究结果表明GBA对流层NO₂柱密度从2005~2018年呈减少的趋势，每年递减约为2.8%.小波系数显示时间演化过程中存在9个月的主振荡周期，冬季浓度较高，夏季较低.人为排放和各种自然因素，导致了GBA对流层NO₂柱浓度月变化在时间和空间上存在明显差异，最小值和最大值分别出现在6和12月，多年平均值分别为3.9665×10¹⁵和12.3423×10¹⁵molec/cm².NO₂在空间分布上呈现明显的空间分异特征，冬季12月最明显.NO₂污染严重的高值区主要出现在中部地区，如广州市、佛山市和中山市，最大的对流层NO₂柱密度可达18.8306×10¹⁵molec/cm²，大约是周边地区的3 倍，且高污染区域向四周逐渐扩散，连成一片.低值区主要在北部的肇庆市和东部的惠州市，多年平均的对流层NO₂柱密度约为7.1400×10¹⁵molec/cm².对流层NO₂柱密度的增长率在不同区域的变化趋势呈现明显的差异，变化范围为-15×10¹⁵~6×10¹⁵molec/cm²，增长率百分比范围为-65%~65%.出现增长的地区主要是肇庆市北部和惠州市东部的低值区；对流层NO₂出现明显减少的区域集中在中部的高值区，减少量最大的地区为广州市、佛山市和中山市交界处.

Temporal and spatial characteristics and influencing factors of NO2 pollution over Guangdong-Hong Kong-Macao Greater Bay Area,China

We analyzed the spatial distribution and temporal variation trend of tropospheric NO₂ over Guangdong-Hong Kong-Macao Greater Bay Area (GBA) using the satellite retrieved data from the Ozone Monitoring Instrument (OMI) sensor, and the influencing factors for these temporal-spatial characteristics. The results showed that the tropospheric NO₂ decreased by about 2.8% per year from 2005 to 2018 over GBA. The wavelet coefficients showed that there was a 9 months of main oscillation period and the higher and lower concentration appeared in winter and summer, respectively. Due to the effects of anthropogenic emissions and various natural factors, the monthly variation of the tropospheric NO₂ was significantly different in time and space over GBA. The minimum and maximum values appeared in June and December, respectively, and the multi-years mean values were 3.9665×10¹⁵ and 12.3423×10¹⁵ molec/cm². The tropospheric NO₂ showed obvious spatial heterogeneity characteristics, the most obvious heterogeneity was in December. The high-value areas with serious NO₂ pollution over GBA were mainly found in the central region, such as Guangzhou, Foshan and Zhongshan cities. The maximum tropospheric NO₂ column density was up to 18.8306×10¹⁵molec/cm². It was about three times that of the surrounding areas, and the high-pollution gradually extended around areas. The low-value areas were mainly in northern Zhaoqing City and eastern Huizhou City, and the average tropospheric NO₂ concentration was about 7.1400×10¹⁵molec/cm². The growth rates showed a significant difference over GBA. The tropospheric NO₂ column density varies from -15×10¹⁵ to 6×10¹⁵molec/cm², and the growth rates from -65% to 65%. The increased areas occurred in northern Zhaoqing City and the eastern Huizhou city. The larger reduced were concentrated in the high value areas in the middle, and the largest reduced were the junction of Guangzhou City, Foshan City and Zhongshan City.