Spatiotemporal distributions of ambient SO2 across China based on satellite retrievals and ground observations: Substantial decrease in human exposure during 2013–2016

Zhang, Hanyue; Di, Baofeng; Liu, Dongren; Li, Jierui; Zhan, Yu

doi:10.1016/j.envres.2019.108795

Cited by 34 publications

(12 citation statements)

References 47 publications

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“…Satellite retrievals of PBL SO 2 reveal possible point sources (Fig. 1d), perhaps from volcanoes, shipping, burning, and industry (Fioletov et al, 2016;Guttikunda et al, 2001;Zhang et al, 2019); however, we caution that cloud contamination may influence the SO 2 retrievals, and it is used here to demonstrate the variety of sources in Asia.…”

Section: Other Datamentioning

confidence: 98%

Measurement report: Long-range transport patterns into the tropical northwest Pacific during the CAMP2Ex aircraft campaign: chemical composition, size distributions, and the impact of convection

et al. 2021

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Abstract. The tropical Northwest Pacific (TNWP) is a receptor for pollution sources throughout Asia and is highly susceptible to climate change, making it imperative to understand long-range transport in this complex aerosol-meteorological environment. Measurements from the NASA Cloud, Aerosol, and Monsoon Processes Philippines Experiment (CAMP2Ex; 24 August to 5 October 2019) and back trajectories from the National Oceanic and Atmospheric Administration Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) were used to examine transport into the TNWP from the Maritime Continent (MC), peninsular Southeast Asia (PSEA), East Asia (EA), and the West Pacific (WP). A mid-campaign monsoon shift on 20 September 2019 led to distinct transport patterns between the southwest monsoon (SWM; before 20 September) and monsoon transition (MT; after 20 September). During the SWM, long-range transport was a function of southwesterly winds and cyclones over the South China Sea. Low- (high-) altitude air generally came from MC (PSEA), implying distinct aerosol processing related to convection and perhaps wind shear. The MT saw transport from EA and WP, driven by Pacific northeasterly winds, continental anticyclones, and cyclones over the East China Sea. Composition of transported air differed by emission source and accumulated precipitation along trajectories (APT). MC air was characterized by biomass burning tracers while major components of EA air pointed to Asian outflow and secondary formation. Convective scavenging of PSEA air was evidenced by considerable vertical differences between aerosol species but not trace gases, as well as notably higher APT and smaller particles than other regions. Finally, we observed a possible wet scavenging mechanism acting on MC air aloft that was not strictly linked to precipitation. These results are important for understanding the transport and processing of air masses with further implications for modeling aerosol lifecycles and guiding international policymaking to public health and climate, particularly during the SWM and MT.

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Section: Other Datamentioning

confidence: 98%

Measurement report: Long-range transport patterns into the tropical northwest Pacific during the CAMP2Ex aircraft campaign: chemical composition, size distributions, and the impact of convection

et al. 2021

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“…Satellite retrievals of PBL SO2 reveal possible point sources ( Fig. 1d), perhaps from volcanoes, shipping, burning, and industry (Fioletov et al, 2016;Guttikunda et al, 2001;Zhang et al, 2019); however, we caution that cloud contamination may influence the SO2 retrievals and are used here 260 to demonstrate the variety of sources in Asia.…”

mentioning

confidence: 86%

Long-range transport patterns into the tropical northwest Pacific during the CAMP2Ex aircraft campaign: chemical composition, size distributions, and the impact of convection

Hilario¹,

Crosbie²,

Shook³

et al. 2020

Preprint

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Abstract. The tropical Western North Pacific (TWNP) is a receptor for pollution sources throughout Asia and is highly susceptible to climate change, making it imperative to understand long-range transport in this complex aerosol-meteorological environment. Measurements from the NASA Cloud, Aerosol, and Monsoon Processes Philippines Experiment (CAMP2Ex; 24 Aug to 5 Oct 2019) and back trajectories from the National Oceanic and Atmospheric Administration Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) were used to examine transport into the TWNP from the Maritime Continent (MC), Peninsular Southeast Asia (PSEA), East Asia (EA), and West Pacific (WP). A mid-campaign monsoon shift on 20 Sep 2019 led to distinct transport patterns between the southwest monsoon (before 20 Sep) and monsoon transition (after 20 Sep). During the southwest monsoon, long-range transport was a function of southwesterly winds and cyclones over the South China Sea. Low (high) altitude air generally came from MC (PSEA), implying distinct aerosol processing related to convection and perhaps wind shear. The monsoon transition saw transport from EA and WP, driven by Pacific northeasterly winds, continental anticyclones, and cyclones over the East China Sea. Composition of transported air differed by emission source and accumulated precipitation along trajectories (APT) as an indicator of convection. MC air was characterized by biomass burning tracers while major components of EA air pointed to Asian outflow and secondary formation. Convective scavenging of PSEA air was evidenced by considerable vertical differences between aerosol species but not trace gases, as well as notably higher APT and smaller particles than other regions. Finally, we observed a possible wet scavenging mechanism acting on MC air aloft that was not strictly linked to precipitation. These results are important for understanding the transport and processing of air masses with further implications for modeling aerosol lifecycles and guiding international policymaking on public health and climate.

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“…CC BY 4.0 License. gradually returned to normal during a period of 1 month ending on 27 March (Zhang et al, 2020a) whereas in Wuhan the lockdown ended on 8 April. The effects of the gradual increase of activities depends on the kind of activity and resulting emissions.…”

Section: Pm2mentioning

confidence: 99%

“…In Shijiazhuang they were highest followed by Wuhan where the SO2 concentrations were similar to those in Chongqing. The common seasonal variation with high concentrations in the winter and low in the summer (Koukouli et al, 2016;Wang et al, 2018b;Zhang et al, 2019) is reflected by the relatively fast decrease in the first 8-10 weeks after which they 435 remained low at 20-30 µg•m -3 in Shijiazhuang and around 10 µg•m -3 in the other two cities. In all three cities there was much interannual variation with substantially lower concentrations in 2018 and 2019 than in the years before.…”

Section: Time Series Of Aerosols and Trace Gases Affecting Air Qualitymentioning

confidence: 99%

“…One side effect of the virus containment measures was the reduction of anthropogenic emissions resulting in smaller concentrations of pollutants as observed from space. In particular, reports on the strong reduction of tropospheric NO2 vertical column densities (TVCDs) appeared for China (e.g., Fan et al, 2020a;Liu et al, 2020;Pei et al, 2020;Zhang et al, 2020a), Italy and other countries in Europe (e.g., Bauwens et al, 2020;Tobí as et al, 85 2020;Mesas-Carrascosa et al, 2020;Sicard et al, 2020;Filippini et al, 2020;Menut et al, 2020) and later over other continents (e.g., Bauwens et al, 2020;Chen et al, 2020;Dantas et al, 2020;Kanniah et al, 2020;Patel et al, 2020;Sharma et al, 2020;Mahato et al, 2020). Reductions in NO2 TVCDs on the order of 50% were reported in the scientific literature (Fan et al, 2020a;Liu et al, 2020;Sicard et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

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Does reduction of emissions imply improved air quality?

Fan

Liu

et al. 2020

Preprint

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Abstract. The air pollution in China is among the highest in the world. However, legislation to reduce pollutant emissions have been successful and concentrations of SO2 (since 2007), aerosols (since 2011) and NO2 (since 2012) have decreased substantially as deduced from satellite and ground-based observations. The strong reduction of the emissions by the end of January 2020, first caused by the Spring Festival holidays and enhanced and extended by the COVID-19 lockdown, offered an opportunity to study the effects on air quality across the country. In particular the reduction of NO2 concentrations observed using the TROPOspheric Monitoring Instrument (TROPOMI) on board the Copernicus Sentinel-5 Precursor satellite was used to quantitatively estimate the lockdown effect. To determine a baseline for the expected concentrations in 2020, we used Ozone Monitoring Instrument (OMI) NO2 TVCD time series from 2011 to 2019 and determined trends for different regions, noticing a possible halt of the decrease in recent years, but for different periods in the south than in the north of east China. Neglecting this leveling leads to overestimation of the lockdown effect on the concentrations in the south, neglecting the trends may lead to underestimation in the north. We also looked at the temporal resolution used in studies on the reduction of the concentrations and noticed the gradual decrease ahead of the Spring Festival, which actually continued during 3 weeks into the lockdown. Using satellite observations of other species and ground-based monitoring data, it was noticed that the expected improvement of air quality due to the reduction of NO2 concentrations was offset by the increase of the concentrations of aerosols and O3 ascribed to meteorological influences and complex chemistry. In the current study we use TROPOMI tropospheric NO2 vertical column densities (TVCDs) together with ground-based monitoring data for NO2, SO2, CO, O3, PM2.5 and PM10 in 11 regions around large cities to evaluate the evolution of their concentrations during 19 weeks after the Spring Festival and their effect on air quality. For comparison, and in an attempt to average out short term (e.g., meteorological) influences, ground based monitoring data were used for the same period in 2015–2019. The results confirm that the strong reduction of NO2 does not always imply good air quality because concentrations of other pollutants may increase. The study shows the different behavior in city clusters in the north and south of China, and inland in the Sichuan and Guanzhong basins. Effect of other holidays and events are small, except in Beijing where the air quality in 2020 was notably better than in previous years. This study was undertaken for east China, but the methodology can also be used for other areas and part of the conclusions are generally applicable.

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Spatiotemporal distributions of ambient SO2 across China based on satellite retrievals and ground observations: Substantial decrease in human exposure during 2013–2016

Cited by 34 publications

References 47 publications

Measurement report: Long-range transport patterns into the tropical northwest Pacific during the CAMP<sup>2</sup>Ex aircraft campaign: chemical composition, size distributions, and the impact of convection

Measurement report: Long-range transport patterns into the tropical northwest Pacific during the CAMP<sup>2</sup>Ex aircraft campaign: chemical composition, size distributions, and the impact of convection

Long-range transport patterns into the tropical northwest Pacific during the CAMP<sup>2</sup>Ex aircraft campaign: chemical composition, size distributions, and the impact of convection

Does reduction of emissions imply improved air quality?

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Spatiotemporal distributions of ambient SO2 across China based on satellite retrievals and ground observations: Substantial decrease in human exposure during 2013–2016

Cited by 34 publications

References 47 publications

Measurement report: Long-range transport patterns into the tropical northwest Pacific during the CAMP&lt;sup&gt;2&lt;/sup&gt;Ex aircraft campaign: chemical composition, size distributions, and the impact of convection

Measurement report: Long-range transport patterns into the tropical northwest Pacific during the CAMP&lt;sup&gt;2&lt;/sup&gt;Ex aircraft campaign: chemical composition, size distributions, and the impact of convection

Long-range transport patterns into the tropical northwest Pacific during the CAMP&lt;sup&gt;2&lt;/sup&gt;Ex aircraft campaign: chemical composition, size distributions, and the impact of convection

Does reduction of emissions imply improved air quality?

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Measurement report: Long-range transport patterns into the tropical northwest Pacific during the CAMP<sup>2</sup>Ex aircraft campaign: chemical composition, size distributions, and the impact of convection

Measurement report: Long-range transport patterns into the tropical northwest Pacific during the CAMP<sup>2</sup>Ex aircraft campaign: chemical composition, size distributions, and the impact of convection

Long-range transport patterns into the tropical northwest Pacific during the CAMP<sup>2</sup>Ex aircraft campaign: chemical composition, size distributions, and the impact of convection