University of Oulu

Reddmann, T., Sinnhuber, M., Wissing, J. M., Yakovchuk, O., and Usoskin, I.: The impact of an extreme solar event on the middle atmosphere: a case study, Atmos. Chem. Phys., 23, 6989–7000,, 2023

The impact of an extreme solar event on the middle atmosphere : a case study

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Author: Reddmann, Thomas1; Sinnhuber, Miriam1; Wissing, Jan Maik2;
Organizations: 1Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Karlsruhe, Germany
2Institute for Physics, University of Rostock, Rostock, Germany
3Space Physics and Astronomy Research Unit and Sodankyla Geophysical Observatory, University of Oulu, Oulu, Finland
Format: article
Version: published version
Access: open
Online Access: PDF Full Text (PDF, 1.3 MB)
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Language: English
Published: Copernicus Publications, 2023
Publish Date: 2023-10-03


A possible impact of an extreme solar particle event (ESPE) on the middle atmosphere is studied for present-day climate and geomagnetic conditions. We consider an ESPE with an occurrence probability of about 1 per millennium. In addition, we assume that the ESPE is followed by an extreme geomagnetic storm (GMS), and we compare the contribution of the two extreme events. The strongest known and best-documented ESPE of 774/5 CE is taken as a reference example and established estimates of the corresponding ionization rates are applied. The ionization rates due to the energetic particle precipitation (EPP) during an extreme GMS are upscaled from analyzed distributions of electron energy spectra of observed GMSs. The consecutive buildup of NOx and HOx by ionization is modeled in the high-top 3D chemistry circulation model KArlsruhe SImulation Model of the middle Atmosphere (KASIMA), using specified dynamics from ERA-Interim analyses up to the stratopause. A specific dynamical situation was chosen that includes an elevated stratosphere event during January and maximizes the vertical coupling between the northern polar mesosphere–lower thermosphere region and the stratosphere; it therefore allows us to estimate a maximum possible impact. The particle event initially produces about 65 Gmol of NOy, with 25 Gmol of excess NOy even after 1 year. The related ozone loss reaches up to 50 % in the upper stratosphere during the first weeks after the event and slowly descends to the mid-stratosphere. After about 1 year, 20 % ozone loss is still observed in the northern stratosphere. The GMS causes strong ozone reduction in the mesosphere but plays only a minor role in the reduction in total ozone. In the Southern Hemisphere (SH), the long-lived NOy in the polar stratosphere, which is produced almost solely by the ESPE, is transported into the Antarctic polar vortex, where it experiences strong denitrification into the troposphere. For this special case, we estimate a NO₃ washout that could produce a measurable signal in ice cores. The reduction in total ozone causes an increase of the UV erythema dose of less than 5 %, which maximizes in spring for northern latitudes of 30∘ and in summer for northern latitudes of about 60.

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Series: Atmospheric chemistry and physics
ISSN: 1680-7316
ISSN-E: 1680-7324
ISSN-L: 1680-7316
Volume: 23
Issue: 12
Pages: 6989 - 7000
DOI: 10.5194/acp-23-6989-2023
Type of Publication: A1 Journal article – refereed
Field of Science: 115 Astronomy and space science
Funding: This work was supported by the German Federal Ministry of Education and Research within the research program ROMIC-2 (project SOLCHECK, grant no. 01LG1906D) and by the Academy of Finland (project ESPERA, grant no. 321882). The AIMOS model is funded by the German Science Foundation (DFG project no. WI4417/2-1). Jan Maik Wissing also acknowledges support by the German Aerospace Center (DLR). The article processing charges for this open-access publication were covered by the Karlsruhe Institute of Technology (KIT).
Academy of Finland Grant Number: 321882
Detailed Information: 321882 (Academy of Finland Funding decision)
Copyright information: © Author(s) 2023. This work is distributed under the Creative Commons Attribution 4.0 License.