The Impact of a Solar Extreme Event on the Middle Atmosphere, a Case Study
Abstract. A possible impact of an extreme solar particle event (ESPE) on the middle atmosphere is studied for the present-day climate and geomagnetic conditions. We consider an ESPE with an occurrence probability of about 1 per millenium combined with an extreme geomagnetic storm (GMS) following the ESPE. 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 geomagnetic storm are up-scaled from analyzed distributions of electron energy spectra of observed geomagnetic storms. The consecutive buildup of NOx and HOx by the ionization is modeled in the high top 3D chemistry circulation model KASIMA, using specified dynamics from ERA-Interim analyses up to the stratopause. A specific dynamical situation was chosen which includes an elevated stratosphere event during January and maximizes the vertical coupling between the Northern polar mesosphere-lower thermosphere region and the stratosphere and therefore allows to estimate a maximum possible impact. The results show a strong enhancement of NOx which causes a substantial decrease of ozone in the mesosphere and stratosphere, and a significant decrease of total ozone in the Northern hemisphere in spring, enduring into the midlatitude summer after the event. The geomagnetic storm causes strong ozone reduction in the mesosphere but plays only a minor role for the reduction in total ozone. In the Southern hemisphere, 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 wash-out which 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°.
Thomas Reddmann et al.
Status: final response (author comments only)
- RC1: 'Comment on acp-2023-31', Anonymous Referee #1, 25 Feb 2023
- RC2: 'Comment on acp-2023-31', Anonymous Referee #2, 01 Mar 2023
Thomas Reddmann et al.
Thomas Reddmann et al.
Viewed (geographical distribution)
Review of Atmospheric Chemistry and Physics paper entitled “The Impact of a Solar Extreme Event on the Middle Atmosphere, a Case Study” by Thomas Reddmann, Miriam Sinnhuber, Jan Maik Wissing, Olesya Yakovchuk, and Ilya Usoskin
The authors study the possible impact of an extreme solar particle event (ESPE) on the middle atmosphere in the present-day climate and geomagnetic conditions. They focus on an ESPE which has an occurrence probability of about 1 every 1000 years. They use a high-top 3D chemistry and circulation model to compute the impact of the solar particle-produced NOx and HOx on atmospheric ozone. The primary computed impact is a substantial decrease of ozone in the mesosphere and stratosphere, which results mostly from the very large enhancement of NOx. The computed reduction in total ozone caused an increase of the ultraviolet (UV) erythema dose of less than 5%. The atmosphere is predicted to recover within one year from this ESPE.
The paper is generally well-written and concerns an analysis of an infrequent, but possibly important, atmospheric perturbation. The authors include several appealing figures, which help illustrate the points of the paper. I recommend publication after my suggested technical corrections dealing with the references are addressed.
Some of the authors of papers middle initial is not given. While this is not a major problem, it would be good if the authors’ middle initial is included. I know a few of them. For example:
Line 347: “Melott, A., Thomas, B., Laird, C.,” should be “Melott, A. L., Thomas, B. C., Laird, C. M.,”
Line 380: “Smart, D., Shea, M., Melott, A., and Laird, C.” should be “Smart, D. F., Shea, M. A., Melott, A. L., and Laird, C. M.,”
Line 382: “Solomon, S., Rusch, D., Gérard, J.-C., Reid, G., and Crutzen, P.,” should be “Solomon, S., Rusch, D. W., Gerard, J.-C., Reid, G. C., and Crutzen, P. J.,”
Line 399: “Vitt, F. and Jackman, C.,” should be “Vitt, F. M., and Jackman, C. H.,”
There are a number of places in the references where the journal name could be abbreviated. Here are some of them:
Line 291: Change “METEOROLOGICAL APPLICATIONS” to “Meteorol. Appl.”
Line 294: Change “The Astrophysical Journal” to “Astrophys. J.”
Lines 296-297, line 391: Change “Atmospheric Chemistry and Physics” to “Atmos. Chem. Phys.”
Line 298: Change “Monthly Notices of the Royal Astronomical Society” to “Mon. Notices Royal Astron. Soc.”
Line 309: Change “Quarterly Journal of the Royal Meteorological Society” to “Q. J. R. Meteorol. Soc.”
Lines 313-314, line 318, line 323, lines 331-332, line 334, lines 373-374, line 386: Change “ATMOSPHERIC CHEMISTRY AND PHYSICS” to “Atmos. Chem. Phys.”
Line 326, line 345, line 400: Change “JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES” to “J. Geophys. Res. Atmos.”
Lines 337-338: Change “Journal of Geophysical Research Atmospheres” to “J. Geophys. Res. Atmos.”
Line 348: Change “Journal of Geophysical” to “J. Geophys. Res.”
Line 351: Change “SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS” to “Space Weather”
Line 356, line 359, lines 362-363, lines 380-381: Change “Journal of Geophysical Research Space Physics” to “J. Geophys. Res. Space Phys.”
Line 369, line 378: Change “JOURNAL OF GEOPHYSICAL RESEARCH SPACE PHYSICS” to “J. Geophys. Res. Space Phys.”
Line 371: Change “SURVEYS IN GEOPHYSICS” to “Surv. Geophys.”
Line 383: Change “Planetary and Space Science” to “Planet. Space Sci.”
Line 389: Change “SCIENTIFIC REPORTS” to “Sci. Rep.”
Line 393: Change “ASTRONOMY & ASTROPHYSICS” to “Astron. Astrophys.”
Line 395: Change “LIVING REVIEWS IN SOLAR PHYSICS” to “Living Rev. Sol. Phys.”
Line 397: Change “JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS” to “J. Atmos. Sol. Terr. Phys.”