基于变分订正TROPOMI卫星数据的京津冀地区NO_(2)时空变化与气象影响分析

Spatiotemporal variations of NO_(2)in Beijing-Tianjin-Hebei region and meteorological impacts based on TROPOMI satellite variational correction

为研究京津冀地区NO_(2)时空变化与气象条件影响,本文利用变分方法订正TROPOMI卫星NO_(2)遥感数据,结合环境气象评估指数(EMI)分析气象条件对NO_(2)浓度变化的影响.结果表明,经过变分方法订正过的NO_(2)浓度具有更可靠和高分辨率的时空分布特征.京津冀西北部地区的NO_(2)浓度低,东部和南部浓度较高.北部燕山、西部太行山形成的半包围地形阻挡了大气污染物在京津冀平原地区的扩散,产生了不利的气象条件.其中,燕山南部的北京、天津和唐山以及太行山东部的保定、石家庄、邢台、邯郸等地气象条件较差,而高海拔地区的张家口、承德、秦皇岛大气扩散条件较好.NO_(2)浓度在春、夏季受到气象条件变化的显著影响,而在秋、冬季受到气象条件变化的影响较小.气象条件对NO_(2)不同浓度区间的作用不同,NO_(2)浓度较低和较高时气象条件对其作用更为显著,而浓度处于转折区间时,气象条件对其影响较小.本研究开展的TROPOMI卫星变分订正、NO_(2)浓度时空分布特征及气象条件影响分析为提升区域大气环境变化中气象作用的认识提供了参考.

In order to study the impact of meteorological conditions on the spatiotemporal variations of NO_(2)in Beijing-Tianjin-Hebei(BTH)region,this study employed the variational processing method to correct the TROPOMI satellite data,and analyzed the influence of meteorological conditions on the NO_(2)variations combined with the environmental meteorological index(EMI).The results showed that the NO_(2)concentrations corrected by the variational processing method are more reliable in the temporal and spatial distribution.The NO_(2)concentrations were low in the northwestern BTH region,and high in the eastern and southern BTH region.The semi-enclosed high topography formed by the Yanshan Mountains in the north and the Taihang Mountains in the west blocked the diffusions of atmospheric pollutants over the BTH Plain,resulting in the unfavorable meteorological conditions.The poor meteorological conditions existed in Beijing,Tianjin and Tangshan in the south of Yanshan Mountains and Baoding,Shijiazhuang,Xingtai and Handan in the east of Taihang Mountains,while the good meteorological conditions for atmospheric diffusions were in the high-altitude regions over Zhangjiakou,Chengde and Qinhuangdao.The NO_(2)concentrations were significantly affected by the change of meteorological conditions in spring and summer,and less affected by the meteorological changes in autumn and winter.The effects of meteorological conditions varied in different NO_(2)concentration ranges,the meteorological conditions exerted more significant impact on low and high levels of NO_(2),and less impacts on the moderate levels of NO_(2).Based on the variation correction of TROPOMI satellite,this study on the spatiotemporal variations of NO_(2)and the meteorological impact could improve the understanding of the meteorological role in regional atmospheric environment changes.