A005-0006
Tropospheric Ozone decreases during spring 2020, caused by the COVID-19 lockdown?
Monday, 7 December 2020
Poster
Klaus-Peter Heue1, Diego G Loyola2, Christophe Lerot3, Fabian Romahn4, Simon Henri Chabrillat3, Yves Christophe3 and Quentin Errera3, (1)German Aerospace Center DLR Oberpfaffenhofen & Technical University Munich, Oberpfaffenhofen, Germany, (2)German Aerospace Center (DLR), Remote Sensing Technology Institute (IMF), Oberpfaffenhofen, Germany, (3)Royal Belgian Institute for Space Aeronomy, Brussels, Belgium, (4)German Aerospace Center (DLR), The Remote Sensing Technology Institute (IMF), Oberpfaffenhofen, Germany
Abstract:
Ozone in the troposphere has mainly two sources: stratospheric intrusion and chemical reactions following the emissions of primary pollutants such as NOx and VOCS. The economic slowdown that followed the lockdown established to limit the CoV-SARS-2 propagation has resulted in a reduction of primary pollutants as NOx. The analysis of the impact of this economic slowdown on tropospheric ozone is not straightforward since no global tropospheric ozone measurement exists. We have thus combined total ozone column measurements with stratospheric ozone analyses to retrieve tropospheric ozone columns. Total ozone columns are those measured by the S5P-TROPOMI satellite instrument while stratospheric ozone columns result of the assimilation of MLS ozone profiles by the BASCOE system.
Based on a first analysis, we observe a decrease of tropospheric ozone during April and May 2020 over many regions in Europe and the USA. Within the cities centres the decrease in NOx caused an increase in tropospheric ozone columns relative to the previous years, due to some non linear effects in the ozone NOx chemistry. The respective increase in the city centres was not yet detected in the satellite based tropospheric ozone observations. Outside the cities however a decrease in the local ozone mixing ratios is expected. Thereby the tropospheric ozone reduction in April-May might be caused by the lockdown.
A reanalysis of the S5P-BASCOE tropospheric based on OFFL TROPOMI total ozone columns might help to quantify the observed effect. In addition the data will be weighted with the downwind distance of city to estimate the effect of atmospheric ozone precursors.
