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Ground-Based Remote Sensing of the Atmosphere during the COVID-19 Lockdown

A special issue of Remote Sensing (ISSN 2072-4292). This special issue belongs to the section "Atmospheric Remote Sensing".

Deadline for manuscript submissions: closed (31 August 2022) | Viewed by 8519

Special Issue Editors

1. Department of Physics, University of Extremadura, 06006 Badajoz, Spain
2. Institute of Earth Sciences (ICT), Institute of Research and Advanced Training, University of Évora, 7000-671 Évora, Portugal
Interests: atmospheric remote sensing; cloud and aerosol properties; radiative transfer modeling; radiative forcing; cloud–aerosol interactions; cloud–aerosol radiative effects; air and water quality remote sensing
Department of Physics, University of Jaén, 23071 Jaén, Spain
Interests: solar radiation; aerosol-cloud-radiation interaction, atmospheric modeling

Special Issue Information

Dear Colleagues,

The COVID-19 pandemic has disrupted our way of life for more than a year. To combat the pandemic, several unprecedented and stringent measures have been taken worldwide, such as social distancing, partial and total lockdowns, extensive travel bans, massive quarantines, etc. In addition to reducing contagion and saving many lives, these restrictive measures have greatly limited human activities such as traffic and industry. This situation has resulted in a direct impact on the emission of aerosols and gases, creating unique conditions for assessing the anthropogenic effect on the composition of the atmosphere. These variations in the aerosol could have also subsequently influenced/affected the cloud characteristics. The quantification of these effects provides important information to discern between natural and anthropogenic effects, which remain one of the main uncertainties in climate change assessment. In this particular situation, ground-based remote sensing, alone or combined with other instrumentation, provides fundamental information to improve our understanding of the anthropogenic impact. Additionally, the impact is expected to differ from region to region according to the measures adopted by the governments. Thus, both global and regional analyses are needed in order to assess the overall impact of this unprecedented situation. Resolving such uncertainties is crucial in constraining the future global and regional climate responses to the combination of greenhouse gases and aerosol emissions. This extraordinary situation makes it highly pertinent and timely to bring together contributions on this topic in the context of a Special Issue. This Special Issue will welcome contributions dealing with the study of the effects of these closures on atmospheric aerosols and gases, and other derived effects on clouds, focusing on passive or active remote sensing from the ground. Combinations of ground-based remote sensing combined with in situ and satellite data are also encouraged.

Dr. Maria A. Obregón
Prof. Dr. Maria João Costa
Dr. Guadalupe Sánchez Hernández
Guest Editors

Manuscript Submission Information

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Keywords

  • Remote sensing
  • Ground-based measurements
  • COVID-19 lockdown
  • Atmospheric aerosols
  • Trace gases
  • Aerosol–cloud interaction
  • Air pollution

Published Papers (4 papers)

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Research

23 pages, 5344 KiB  
Article
Footprint of the 2020 COVID-19 Lockdown on Column-Integrated Aerosol Parameters in Spain
by María Ángeles Obregón, Blanca Martín and Antonio Serrano
Remote Sens. 2023, 15(12), 3167; https://doi.org/10.3390/rs15123167 - 18 Jun 2023
Viewed by 845
Abstract
The lockdown adopted in Spain to combat the global pandemic due to the coronavirus disease (COVID-19) led to a significant reduction in the emission of aerosols produced by road traffic and industry. This study aims to detect changes in column aerosols in Spain [...] Read more.
The lockdown adopted in Spain to combat the global pandemic due to the coronavirus disease (COVID-19) led to a significant reduction in the emission of aerosols produced by road traffic and industry. This study aims to detect changes in column aerosols in Spain due to the COVID-19 lockdown. High-quality AErosol RObotic NETwork (AERONET) measurements of AOD (aerosol optical depth), AE (Ångström exponent) and SSA (single scattering albedo) over the period 2012–2020 are used for this purpose. Ten AERONET stations with available measurements during the lockdown and post-lockdown periods with a long previous data record are selected. The stations are well distributed throughout Spain, covering different areas and population densities. A comprehensive set of three statistical tests are applied to assess general changes in the dataset, the central tendency and low and high values for each parameter. The analyses are conducted for the 2020 lockdown and post-lockdown periods by comparing daily aerosol data with the measurements recorded for the same calendar days during the period 2012–2019. The results indicate a general increase in AOD during the lockdown and a decrease during the post-lockdown. While AE shows no overall behaviour, SSA is the parameter most sensitive to changes in anthropogenic contribution, with an overall significant increase in almost all the stations during both lockdown and post-lockdown periods. The study contributes to addressing the impact of the COVID-19 lockdown and provides methodologies to detect its footprint. Full article
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30 pages, 11512 KiB  
Article
COVID-19 Pandemic: Impacts on Air Quality during Partial Lockdown in the Metropolitan Area of São Paulo
by Débora Souza Alvim, Dirceu Luis Herdies, Sergio Machado Corrêa, Luana Santamaria Basso, Bushra Khalid, Gabriella Fernandes Prazeres Silva, Gabriel Oyerinde, Nicolli Albuquerque de Carvalho, Simone Marilene Sievert da Costa Coelho and Silvio Nilo Figueroa
Remote Sens. 2023, 15(5), 1262; https://doi.org/10.3390/rs15051262 - 24 Feb 2023
Cited by 1 | Viewed by 1299
Abstract
Air pollution has become one of the factors that most affect the quality of life, human health, and the environment. Gaseous pollutants from motor vehicles have a significantly harmful effect on air quality in the Metropolitan Area of São Paulo (MASP)—Brazil. Motor vehicles [...] Read more.
Air pollution has become one of the factors that most affect the quality of life, human health, and the environment. Gaseous pollutants from motor vehicles have a significantly harmful effect on air quality in the Metropolitan Area of São Paulo (MASP)—Brazil. Motor vehicles emit large amounts of particulate matter (PM), carbon monoxide (CO), nitrogen oxides (NOx), and volatile organic compounds (VOCs), the last three acting as the main tropospheric ozone (O3) precursors. In this study, we evaluated the effects of these pollutants on air quality in the MASP during the partial lockdown that was imposed to ensure the social distancing necessitated by the COVID-19 pandemic. We compared the monthly data for nitrogen dioxide (NO2) from the Ozone Monitoring Instrument (OMI) and CO, SO2, and BC from MERRA-2 for the period between April and May 2020 (during the pandemic) with the average for the same period for the (pre-pandemic) years 2017 to 2019 in the southeast region of Brazil. The meteorological and pollutant concentration data from the CETESB air quality monitoring stations for the MASP were compared with the diurnal cycle of three previous years, with regard to the monthly averages of April and May (2017, 2018, and 2019) and the same period in 2020, when the partial lockdown was first imposed in southeast Brazil. Our findings showed that there was a decrease in NO2 concentrations ranging from 10% to more than 60% in the MASP and the Metropolitan Area of Rio de Janeiro (MARJ), whereas in the Metropolitan Area of Belo Horizonte and Vitoria (MABH and MAV, respectively), there was a reduction of around 10%. In the case of the concentrations of CO and BC from MERRA-2, there was a considerable decrease (approx. 10%) during the period of partial lockdown caused by COVID-19 throughout almost the entire state of São Paulo, particularly in the region bordering the state of Rio de Janeiro. The concentration of SO2 from MERRA-2 was 5 to 10% lower in the MASP and MARJ and the west of the MABH, and there was a decrease of 30 to 50% on the border between the states of São Paulo and Rio de Janeiro, while in the MAV region, there was an increase in pollutant levels, as this region was not significantly affected by the COVID-19 pandemic. Sharp reductions in the average hourly concentrations of CO (38.8%), NO (44.9%), NO2 (38.7%), and PM2.5 (6%) were noted at the CETESB air quality monitoring stations in the MASP during the partial lockdown in 2020 compared with the hourly average rate in the pre-pandemic period. In contrast, there was an increase of approximately 16.0% in O3 concentrations in urban areas that are seriously affected by vehicular emissions, which is probably related to a decrease in NOx. Full article
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25 pages, 6510 KiB  
Article
Tropospheric and Surface Nitrogen Dioxide Changes in the Greater Toronto Area during the First Two Years of the COVID-19 Pandemic
by Xiaoyi Zhao, Vitali Fioletov, Ramina Alwarda, Yushan Su, Debora Griffin, Dan Weaver, Kimberly Strong, Alexander Cede, Thomas Hanisco, Martin Tiefengraber, Chris McLinden, Henk Eskes, Jonathan Davies, Akira Ogyu, Reno Sit, Ihab Abboud and Sum Chi Lee
Remote Sens. 2022, 14(7), 1625; https://doi.org/10.3390/rs14071625 - 28 Mar 2022
Cited by 8 | Viewed by 2738
Abstract
We present tropospheric nitrogen dioxide (NO2) changes observed by the Canadian Pandora measurement program in the Greater Toronto Area (GTA), Canada, and compare the results with surface NO2 concentrations measured via in situ instruments to assess the local emission changes [...] Read more.
We present tropospheric nitrogen dioxide (NO2) changes observed by the Canadian Pandora measurement program in the Greater Toronto Area (GTA), Canada, and compare the results with surface NO2 concentrations measured via in situ instruments to assess the local emission changes during the first two years of the COVID-19 pandemic. In the City of Toronto, the first lockdown period started on 15 March 2020, and continued until 24 June 2020. ECMWF Reanalysis v5 (ERA-5) wind information was used to facilitate the data analysis and reveal detailed local emission changes from different areas of the City of Toronto. Evaluating seven years of Pandora observations, a clear NO2 reduction was found, especially from the more polluted downtown Toronto and airport areas (e.g., declined by 35% to 40% in 2020 compared to the 5-year mean value from these areas) during the first two years of the pandemic. Compared to the sharp decline in NO2 emissions in 2020, the atmospheric NO2 levels in 2021 started to recover, but are still below the mean values in pre-pandemic time. For some sites, the pre-pandemic NO2 local morning rush hour peak has still not returned in 2021, indicating a change in local traffic and commuter patterns. The long-term (12 years) surface air quality record shows a statistically significant decline in NO2 with and without April to September 2020 observations (trend of −4.1%/yr and −3.9%/yr, respectively). Even considering this long-term negative trend in NO2, the observed NO2 reduction (from both Pandora and in situ) in the early stage of the pandemic is still statistically significant. By implementing the new wind-based validation method, the high-resolution satellite instrument (TROPOMI) can also capture the local NO2 emission pattern changes to a good level of agreement with the ground-based observations. The bias between ground-based and satellite observations during the pandemic was found to have a positive shift (5–12%) than the bias during the pre-pandemic period. Full article
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23 pages, 7517 KiB  
Article
Reduction of Air Pollution in Poland in Spring 2020 during the Lockdown Caused by the COVID-19 Pandemic
by Patryk Tadeusz Grzybowski, Krzysztof Mirosław Markowicz and Jan Paweł Musiał
Remote Sens. 2021, 13(18), 3784; https://doi.org/10.3390/rs13183784 - 21 Sep 2021
Cited by 8 | Viewed by 2363
Abstract
The COVID-19 pandemic has affected many aspects of human well-being including air quality. The present study aims at quantifying this effect by means of ground-level concentrations of NO2, PM2.5, as well as aerosol optical depth (AOD) measurements and tropospheric [...] Read more.
The COVID-19 pandemic has affected many aspects of human well-being including air quality. The present study aims at quantifying this effect by means of ground-level concentrations of NO2, PM2.5, as well as aerosol optical depth (AOD) measurements and tropospheric NO2 column number density (NO2 TVCD), during the imposed governmental restrictions in spring 2020. The analyses were performed for both urban and non-built-up areas across the whole of Poland accompanied by Warsaw (urban site) and Strzyzow (a background site). The results revealed that mean PM2.5 concentrations in spring 2020 for urban and non-built-up areas across Poland and for Warsaw were 20%, 23%, 15% lower than the 10-year average, respectively. Analogous mean NO2 concentrations were lower by 20%, 18%, 30% and NO2 TVCD revealed 9%, 4%, 9% reductions in 2020 as compared to 2019. Regarding mean AOD, retrieved from MERRA-2 reanalysis, it was found that for the whole of Poland during spring 2020 the reduction in AOD as compared to the 10-year average was 15%. The contribution of the lockdown within total air pollution reduction is not easily assessable due to anomalous weather conditions in 2020 which resulted in advection of clean air masses identified from MERRA-2 reanalysis and Strzyzow observatory. Full article
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