Impact of COVID-19 Lockdown Measures on Air Quality as Observed by the TROPOMI/S5p Instrument

Abstract:

The global health threat due to the coronavirus COVID-19 pandemic that humankind is facing since early 2020, led to unprecedented measures taken by different governments worldwide. Social distancing, banning of gatherings and travels, closing of schools, universities, non-essential product shops and borders..., all those measures resulted in a drastic reduction in traffic and industrial activities in non-essential sectors, thereby affecting our emissions to the atmosphere.

In this work, we investigate the presence of COVID-19-related signals in air quality measurements from space. This is done by exploiting the observations of the TROPOMI instrument onboard ESA’s Sentinel-5 Precursor satellite for a number of trace gases as indicators of anthropogenic activity. For this study, we use the TROPOMI operational product portfolio, which includes tropospheric NO₂, CO, SO_2, HCHO, complemented by additional scientific products such as glyoxal. We support the space-based assessment with ground-based in-situ and remote sensing observations of a number of pollutants. We focus on worldwide industrial/highly populated regions where strong lockdown measures have been taken (e.g. China, India, Europe, US). In those regions, we investigate the correlation between the expected reductions of atmospheric pollutants and the timing of the lockdown restrictions, thereby carefully disentangling possible COVID-related reductions from the natural variability such as seasonal variations or changes in meteorological conditions.