COVID‐19 Crisis Reduces Free Tropospheric Ozone Across the Northern Hemisphere

Media type: E-Article

Title: COVID‐19 Crisis Reduces Free Tropospheric Ozone Across the Northern Hemisphere

Contributor: Steinbrecht, Wolfgang [Author]; Kubistin, Dagmar [Author]; Plass‐Dülmer, Christian [Author]; Davies, Jonathan [Author]; Tarasick, David W. [Author]; Gathen, Peter von der [Author]; Deckelmann, Holger [Author]; Jepsen, Nis [Author]; Kivi, Rigel [Author]; Lyall, Norrie [Author]; Palm, Matthias [Author]; Notholt, Justus [Author]; Kois, Bogumil [Author]; Oelsner, Peter [Author]; Allaart, Marc [Author]; Piters, Ankie [Author]; Gill, Michael [Author]; Van Malderen, Roeland [Author]; Delcloo, Andy W. [Author]; Sussmann, Ralf [Author]; Mahieu, Emmanuel [Author]; Servais, Christian [Author]; Romanens, Gonzague [Author]; Stübi, Rene [Author]; [...]

imprint: GEO-LEOe-docs (FID GEO), 2021-02-26

Language: English

DOI: https://doi.org/10.23689/fidgeo-4331

Keywords: COVID‐19 ; emissions ; ozone ; troposphere

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Description: Throughout spring and summer 2020, ozone stations in the northern extratropics recorded unusually low ozone in the free troposphere. From April to August, and from 1 to 8 kilometers altitude, ozone was on average 7% (≈4 nmol/mol) below the 2000–2020 climatological mean. Such low ozone, over several months, and at so many stations, has not been observed in any previous year since at least 2000. Atmospheric composition analyses from the Copernicus Atmosphere Monitoring Service and simulations from the NASA GMI model indicate that the large 2020 springtime ozone depletion in the Arctic stratosphere contributed less than one‐quarter of the observed tropospheric anomaly. The observed anomaly is consistent with recent chemistry‐climate model simulations, which assume emissions reductions similar to those caused by the COVID‐19 crisis. COVID‐19 related emissions reductions appear to be the major cause for the observed reduced free tropospheric ozone in 2020. ; Plain Language Summary: Worldwide actions to contain the COVID‐19 virus have closed factories, grounded airplanes, and have generally reduced travel and transportation. Less fuel was burnt, and less exhaust was emitted into the atmosphere. Due to these measures, the concentration of nitrogen oxides and volatile organic compounds (VOCs) decreased in the atmosphere. These substances are important for photochemical production and destruction of ozone in the atmosphere. In clean or mildly polluted air, reducing nitrogen oxides and/or VOCs will reduce the photochemical production of ozone and result in less ozone. In heavily polluted air, in contrast, reducing nitrogen oxides can increase ozone concentrations, because less nitrogen oxide is available to destroy ozone. In this study, we use data from three types of ozone instruments, but mostly from ozonesondes on weather balloons. The sondes fly from the ground up to 30 kilometers altitude. In the first 8 km, we find significantly reduced ozone concentrations in the northern extratropics during spring and summer of ...

Access State: Open Access

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