SMuK 2021 – scientific programme

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UP: Fachverband Umweltphysik

UP 5: Atmospheric Trace Gases

UP 5.1: Invited Talk

Friday, September 3, 2021, 14:00–14:30, H7

Ozone in the troposphere responds to reduced precursor emissions during the COVID-19 pandemic — •Wolfgang Steinbrecht — Deutscher Wetterdienst, Hohenpeissenberg, Germany

The COVID-19 pandemic has provided an accidental global air-quality experiment, which tests observational capabilities, and also our understanding of atmospheric chemistry and transport. Measures to curb spreading of the COVID-19 pandemic have reduced world-wide fuel consumption and associated emissions. Air-traffic and surface transportation were the sectors with the largest emission reductions, up to 80%. Both sectors are important sources of nitrogen oxides and volatile organic compounds (VOC), the main precursors for photochemical production of ozone in the troposphere. In spring and summer 2020, observations of ozone in the free troposphere show an unprecedented reduction by about 7%, over much of the Northern Hemisphere. Model simulations reproduce this ozone reduction. In addition, they attribute about one third each of the observed reduction to reduced air-traffic, reduced surface transportation, and 2020 meteorological conditions (including the exceptional ozone hole of the Arctic stratosphere in spring 2020). Different from the ozone reduction observed in the free troposphere, data from polluted urban and industrial regions often show increased ozone during the pandemic - consistent with well-known non-linearities in tropospheric ozone chemistry (NOx saturation).