基于国产卫星遥感的北京冬奥会空气质量监测和追因

Observations and tracing of air quality during the Beijing Winter Olympic Games using Chinese satellite hyperspectral measurements

2021年9月,高光谱观测卫星高分五号02星成功发射,有效提升了我国大气环境遥感监测的综合应用水平,为空气质量保障提供了自主可控的遥感数据支撑.在2022年1~3月北京-张家口冬奥会期间,我们近实时反演获取了高分五号02星污染气体监测产品,并通过生态环境部卫星环境应用中心为冬奥会提供监测分析日报.本文分析了冬奥会期间北京及周边重点城市的对流层二氧化氮(NO_(2))时空分布特征,探讨了气象条件和人为排放控制措施对冬奥会期间NO_(2)浓度的影响.国产卫星反演结果表明,冬奥会期间华北地区平均对流层NO_(2)柱浓度稳定在3.75×10^(15)molecules/cm^(2)以下,低于会前和会后.不同城市在冬奥会期间NO_(2)柱浓度下降幅度在53.1%~70.1%之间,说明临时管控政策对空气质量改善效果显著,但不同城市的减排实施有差异.这与国控站点近地面NO_(2)监测结果具有较好的一致性.冬奥会期间出现两天NO_(2)浓度高值,主要受不利风场条件影响.本文还通过建立广义相加模型来区分和量化人为减排等非气象因素与气象因素对于对流层NO_(2)浓度变化的贡献,保定、北京、天津和太原在冬奥会期间的NO_(2)浓度分别下降了48.2%、67.5%、48.8%和72.8%,其中人为排放和气象因素分别贡献了41.8%、32.0%、30.0%、42.8%和6.4%、35.6%、18.8%、30.1%.总体上,气象因素影响要弱于排放临时管控措施.该研究首次利用国产卫星为冬奥会提供污染气体监测和溯源分析,有力支撑了我国大气环境遥感监测的应用.

In September 2021,China’s Gaofen-5B satellite carrying the environmental trace gas monitoring instrument(EMI)was successfully launched,which promoted the self-directed development of remote sensing monitoring in China.During the Beijing-Zhangjiakou Winter Olympics,we used the satellite product to provide remote sensing data support for air quality assurance at the Winter Olympics.This paper introduced the domestic hyperspectral satellite product of tropospheric NO_(2)retrievals,analysed the spatial and temporal distribution of NO_(2)pollution in Beijing and its surrounding key cities during the 2022 Winter Olympic Games from January to March,and further discussed the influence of meteorological conditions and anthropogenic emission control measures on the atmospheric NO_(2)concentration during the Winter Olympic Games.The results showed that the average tropospheric NO_(2)column concentration in North China during the Winter Olympics was approximately 3.75×10^(15)molecules/cm^(2),which was significantly lower than that before and after the Winter Olympics.NO_(2)concentrations in major cities decreased between 53.14%and 70.07%,indicating that the temporary control policy during the Winter Olympics had a significant effect.However,the implementation of the policy varies in different cities,which is consistent with the in situ measurements of NO_(2)concentration by the national air quality sites.High concentrations of tropospheric NO_(2)occurred on two days during the event,mainly due to unfavourable wind fields.Moreover,a generalized additive model was established to distinguish and quantify the contribution of meteorological and anthropogenic factors to the change in tropospheric NO_(2)concentrations.For example,the decreases in NO_(2)concentrations in Baoding,Beijing,Tianjin and Taiyuan during the event were 48.2%,67.5%,48.8%and 72.8%,respectively,and emission controls and meteorology contributed 41.8%,32.0%,30.0%,42.8%and 6.4%,35.6%,18.8%,30.1%,respectively.In general,the influence of meteorological factors on the sharp decrease in NO_(2)concentration was significantly weaker than the temporary measures of NOX emission control.Satellite air quality monitoring revealed the spatial and temporal variations in air pollutants during the event.Further analysis based on the GAM model can evaluate the effectiveness of air quality control measures and benefit environmental policy-makers.