Poster de conférence
Résumé : China was the first country to undergo large‐scale lockdowns in response to the pandemic in early 2020 and a progressive return to normalization after April 2020. Substantial decreases in pollutants levels and their subsequent recovery were revealed by spaceborne observations and in situ measurements of nitrogen dioxide (NO2), a predominantly anthropogenic compound and an important precursor for ozone and aerosol formation. This study adds to this picture with the analysis of satellite data of oxygenated volatile organic compounds (OVOCs), namely formaldehyde (HCHO), glyoxal (CHOCHO) and peroxyacetyl nitrate (PAN). The observations reveal important changes in pollutants levels in response to the pandemic‐induced shutdowns and subsequent drop in pollutant emissions. In February 2020, when the shutdowns were at their peak, the observed declines in the OVOC levels were generally weaker (less than 20%) than the substantial NO2 reductions (‐40%). In May 2020, the observations reveal moderate decreases for NO2 (‐15%) and PAN (‐21%), and small changes for CHOCHO (‐3%) and HCHO (6%). Simulations with a regional atmospheric model using anthropogenic emissions taking into account the reductions during the shutdowns based on activity data, explain to a large extent the observed decreases between 2020 and 2019 in regions affected by the lockdowns. In areas where biomass burning and biogenic sources are dominant, the observed changes reflect the interannual variability of these sources, and are well captured by the model simulation.

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