Satellite UV-Vis spectroscopy: implications for air quality trends and their driving forces in China during 2005–2017

Abstract

<p>Abundances of a range of air pollutants can be inferred from satellite UV-Vis spectroscopy measurements by using the unique absorption signatures of gas species. Here, we implemented several spectral fitting methods to retrieve tropospheric NO<sub>2</sub>, SO<sub>2</sub>, and HCHO from the ozone monitoring instrument (OMI), with radiative simulations providing necessary information on the interactions of scattered solar light within the atmosphere. We analyzed the spatial distribution and temporal trends of satellite-observed air pollutants over eastern China during 2005–2017, especially in heavily polluted regions. We found significant decreasing trends in NO<sub>2</sub> and SO<sub>2</sub> since 2011 over most regions, despite varying temporal features and turning points. In contrast, an overall increasing trend was identified for tropospheric HCHO over these regions in recent years. Furthermore, generalized additive models were implemented to understand the driving forces of air quality trends in China and assess the effectiveness of emission controls. Our results indicated that although meteorological parameters, such as wind, water vapor, solar radiation and temperature, mainly dominated the day-to-day and seasonal fluctuations in air pollutants, anthropogenic emissions played a unique role in the long-term variation in the ambient concentrations of NO<sub>2</sub>, SO<sub>2</sub>, and HCHO in the past 13 years. Generally, recent declines in NO<sub>2</sub> and SO<sub>2</sub> could be attributed to emission reductions due to effective air quality policies, and the opposite trends in HCHO may urge the need to control anthropogenic volatile organic compound (VOC) emissions.</p>

The reduction in C<sub>2</sub>H<sub>6</sub> from 2015 to 2020 over Hefei, eastern China, points to air quality improvement in China

“…GAMs regression is better than the traditional statistical models in dealing with nonlinear fittings (Veaux and Richard, 2012). For climate change applications, where there are many nonlinear relationships between variables, GAMs regression is particularly attractive (Zhang et al, 2019).…”

“…The Hefei site is not yet affiliated with the NDACC network, but its observation routine has followed the NDACC standard convention since 2015 (Sun et al, 2018a). As the consequence of a series of actions for emission control, air pollution over China in recent years has been significantly decreased (Zhang et al, 2019;Zheng et al, 2018). However, the atmospheric pollution over densely populated and highly industrialized eastern China is still severe (Zhang et al, 2019;Zheng et al, 2018).…”

“…As the consequence of a series of actions for emission control, air pollution over China in recent years has been significantly decreased (Zhang et al, 2019;Zheng et al, 2018). However, the atmospheric pollution over densely populated and highly industrialized eastern China is still severe (Zhang et al, 2019;Zheng et al, 2018). The complexity, extension, and severity of the atmospheric pollution in eastern China are still unrivaled compared with the rest of world (Lu et al, 2018;Zheng et al, 2018).…”

Evaluation of the accuracy of the Sentinel-5 Precursor operational SO<sub>2</sub> products over China

“…但是欧洲业务SO 2 数据标志了更大范围的 污染, 与其他卫星数据和我国SO 2 大幅减 排的事实相悖 [11] . Fioletov等人 [23] 在计算 TROPOMI仪器响应函数v3.0.0 [19] 地表反射率 OMI月平均气候统计数据 [20] 云 哨兵5号二级云产品数据 [10] 反演波段 312~326 nm 310.5~326 nm SO 2 先验廓线 TM5模拟每日廓线 [15] GEOS-Chem模拟月平均廓线 [20] SO 2 吸收截面 203 K [21] 203, 223, 243, 273, 293 K [21] O 3 吸收截面 228, 243 K [22] 218, 228, 243, 295 K [22] 低阶多项式 5 无…”

First observation of tropospheric nitrogen dioxide from the Environmental Trace Gases Monitoring Instrument onboard the GaoFen-5 satellite

“…As a result, China is experiencing a series of severe air pollution problems 7,8 . In addition to measuring NO 2 distribution directly from space, applications of satellite remote sensing may include estimations of pollutant emissions 9 , air quality trend detection 10 , model validation, and assimilation of satellite data 11 . Figure 1a illustrates the optical design of the EMI satellite instrument.…”