Observation of NO_x enhancement and ozone depletion in the Northern and Southern Hemispheres after the October–November 2003 solar proton events

Abstract

The large solar storms in October–November 2003 produced enormous solar proton events (SPEs) where high energetic particles reached the Earth and penetrated into the middle atmosphere in the polar regions. At this time, the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) was observing the atmosphere in the 6–68 km altitude range. MIPAS observations of NOx (NO + NO2) and O3 of the period from 25 October to 14 November 2003 are the first global measurements of NOx species, covering both the summer (daylight) and winter (dark) polar regions during an SPE. Very large values of NOx in the upper stratosphere of 180 ppbv (parts per billion by volume) have been measured, and a large asymmetry in northern and southern polar cap NOx enhancements was found. Arctic mean polar cap (>60°) NOx enhancements of 20 to 70 ppbv between 40 to 60 km lasted for at least 2 weeks, while the Antarctic mean NOx enhancement was between 10 and 35 ppbv and was halved after 2 weeks. Ozone shows depletion signatures associated with both HOx (H + OH + HO2) and NOx enhancements but at different timescales. Arctic lower mesospheric (upper stratospheric) ozone is reduced by 50–70% (30–40%) for about 2 weeks after the SPEs. A smaller ozone depletion signal was observed in the Antarctic atmosphere. After the locally produced Arctic middle and upper stratospheric as well as mesospheric NOx enhancement, large amounts of NOx were observed until the end of December. These are explained by downward transport processes. These enhancements drastically declined with the mid‐December stratospheric warming. Significant O3 depletion was observed inside the polar vortex in a wide altitude range during this period. From mid‐January until the end of March 2004, MIPAS observed extraordinary high values of NO2 in the upper stratosphere of the northern polar region (mean in‐vortex values up to 350 ppbv at ∼54 km), which seem to be caused by the unusually strong vortex and downward transport at that time together with an uncommonly large auroral activity starting with the solar storms in October–November and continuing over the winter. In‐vortex ozone was observed to significantly decline in the mid‐February to late March period above the 1750 K potential temperature level.

Middle atmospheric changes caused by the January and March 2012 solar proton events

“…Although the impacted altitudes are similar between the measurements and the model predictions, the models indicate a somewhat larger NO x change in both hemispheres, when compared with MI-PAS observations. Some of this larger model predicted SPEcaused NO y enhancement can be explained by the finer vertical grid of the model (1-2 km in the mesosphere) compared to the MIPAS vertical field-of-view of about 3 km (López-Puertas et al, 2005a). As for January (see Fig.…”

“…A number of constituents have been observed and modeled to be modified by SPEs (e.g., López-Puertas et al, 2005a, b;von Clarmann et al, 2005;Jackman et al, 2011;Damiani et al, 2012). We will focus on the SPE-caused impact on HO x , NO x , and ozone in this study.…”

“…ACE-FTS (hereinafter referred to as ACE) and MIPAS (Fischer et al, 2008) measured both NO and NO 2 (e.g., Rinsland et al, 2005;López-Puertas et al, 2005a). We defined NO x in Sect.…”

“…Although SPEs and their middle atmospheric constituent influences have been studied before (e.g., Swider and Keneshea, 1973;Heath et al, 1977;Solomon et al, 1981;McPeters and Jackman, 1985;Randall et al, 2001;López-Puertas et al, 2005a;von Clarmann et al, 2005;Verronen et al, , 2008Verronen et al, , 2011aKrivolutsky et al, 2006;Funke et al, 2011;Jackman et al, 1990Jackman et al, , 2001Jackman et al, , 2008Jackman et al, , 2009Sinnhuber et al, 2012), each new event offers a chance to investigate the SPE-caused atmospheric perturbation under somewhat different conditions. Also, such events have been shown to cause some longer lasting stratospheric changes (e.g., Randall et al, 2001;Jackman et al, 2008Jackman et al, , 2009) and need to be considered within the context of other ongoing stratospheric changes (WMO, 2011).…”

Analysis and parameterisation of ionic reactions affecting middle atmospheric HO<sub>x</sub> and NO<sub>y</sub> during solar proton events

“…SPEs and their influence on ozone have played a large role in the research due to the profound impact of SPEs and the availability of ozone observations from several satellite-based instruments McPeters and Jackman, 1985;Reid et al, 1991;Jackman et al, 2001;Seppälä et al, 2004;López-Puertas et al, 2005a;. In recent years, changes in other minor species have received substantial attention after a wealth of satellite observations of the winter polar regions became Published by Copernicus Publications on behalf of the European Geosciences Union.…”