Recent advances in satellite mapping of global air quality: evidences during COVID-19 pandemic

Abstract

There was a significant decline in air pollution in different parts of the world due to enforcement of lockdown by many countries to check the spread of the coronavirus (COVID-19) pandemic. In particular, commercial and industrial activities had been limited globally with restricted air and surface traffic movements in response to social distancing and isolation. Both satellite remote sensing and ground-based monitoring were used to measure the change in the air quality. There was momentous decline in the averaged concentrations of nitrogen dioxide (NO 2 ), carbon dioxide (CO 2 ), sulphur dioxide (SO 2 ), methane (CH 4 ) and aerosols. Many cities across India, China and several major cities in Europe observed strong reductions in nitrogen dioxide levels dropping by around 40–50% owing to lockdowns. Similarly, concentrations of SO 2 in polluted areas in India, especially around large coal-fired power plants and industrial areas decreased by around 40% as evidenced by the comparative satellite mapping during April 2019 and April 2020. Recent advances in sensors on board various satellites played a significant role in real-time monitoring of emission regimes over various parts of the world. The satellite data is relying upon single scene profusion for real-time air quality measurements, and also using averaged dataset over certain time-period. The daily global-scale remote sensing data of NO 2 , as measured through the Copernicus Sentinel-5 Precursor Tropospheric Monitoring Instrument (S5p/TROPOMI) of European Space Agency (ESA), indicated exceptional decreases in tropospheric NO 2 pollution in urban areas. Similarly, Greenhouse gases Observing Satellite (GOSAT) of Japan Aerospace Exploration Agency, with a repeat cycle of three days helped in assessing the sources and sinks of CO 2 and CH 4 on a sub-continental scale. Supplementary Information The online version contains supplementary material available at 10.1007/s42398-021-00166-w.

The impact of COVID-19 on the sustainability of the environment, animal health and food security, and safety

“… 2020 ). Many cities witnessed a significant drop in air pollutants in a range of 30 to 60%, owing to countrywide lockdowns (Dutta et al 2021 ). In Saudi Arabia, the COVID-19 lockdown was an advantage to the environment.…”

“…NASA’s various satellite image observations indicate that Western Europe, Northern China, the USA, and the Indian subcontinent experienced a noticeable improvement in air pollution during the pandemic compared to the same era in past years (Dutta et al 2021 ).…”

Then and Now: COVID-19 Pandemic Lockdown Misfire Atmospheric Methane over India

“…Behera et al (2021) reported that the seasonal variability of CH4 was linked to crop-residual burning, and the study defined higher CH4 values in 2021. Similarly, Dutta et al (2021) argued that the increase in CH4 over India agreed with the global rise using Sentinel-5P. However, the data gaps in their visualized analysis do not fully support their conclusion.…”

“…Being the 237 season for Rabi crops (i.e., wheat, barley, etc. ), the soil remains aerobic during pre-monsoon, 238 unlike monsoonal season, which favors soil methanogenesis (Dutta et al, 2021). However, the lack of data coverage in the analyzing period demands a need for an improved measurement network and focus on CH4 emissions over India.…”

A spatiotemporal analysis of NO2 concentrations during the Italian 2020 COVID‐19 lockdown

“…Several environmental studies revealed that restrictions on mobility during the lockdown had a positive effect on NO levels, even if not homogeneously across the considered spatial domains. For example, the broadly publicized data from the Copernicus Sentinel‐5P satellite (Ali, Abbas, Qamer, & Irteza, 2021; Ali, Abbas, Qamer, Wong, et al, 2021; Bar et al, 2021; Dutta et al, 2021; Muhammad et al, 2020) recorded for NO a sharp drop, in the range 20%–55%, during January–April 2020 compared to 2019 in many cities in China, India, Pakistan, Western Europe, and United States. With regards to Italy, Bauwens et al (2020) found the average TROPOMI NO column during the lockdown period in 2020 to be between 38 ( 10%) lower than during the same period in 2019 in Milan.…”