COVID-19 Crisis Reduces Free Tropospheric Ozone Across the Northern Hemisphere.
Wolfgang SteinbrechtDagmar KubistinChristian Plass-DülmerJonathan DaviesDavid W TarasickPeter von der GathenHolger DeckelmannNis JepsenRigel KiviNorrie LyallMatthias PalmJustus NotholtBogumil KoisPeter OelsnerMarc AllaartAnkie PitersMichael GillRoeland Van MalderenAndy W DelclooRalf SussmannEmmanuel MahieuChristian ServaisGonzague RomanensRene StübiGerard AncelletSophie Godin-BeekmannShoma YamanouchiKimberly StrongBryan JohnsonPatrick CullisIrina PetropavlovskikhJames W HanniganJose-Luis HernandezAna Diaz RodriguezTatsumi NakanoFernando ChouzaThierry LeblancCarlos TorresOmaira GarciaAmelie N RöhlingMatthias SchneiderThomas BlumenstockMatt TullyClare Paton-WalshNicholas JonesRichard QuerelSusan E StrahanRyan M StaufferAnne M ThompsonAntje InnessRichard EngelenKai-Lan ChangOwen R CooperPublished in: Geophysical research letters (2021)
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.