Short- and medium-term atmospheric constituent effects of very large solar proton events

Abstract

Abstract. Solar eruptions sometimes produce protons, which impact the Earth's atmosphere. These solar proton events (SPEs) generally last a few days and produce high energy particles that precipitate into the Earth's atmosphere. The protons cause ionization and dissociation processes that ultimately lead to an enhancement of odd-hydrogen and oddnitrogen in the polar cap regions (>60 • geomagnetic latitude). We have used the Whole Atmosphere Community Climate Model (WACCM3) to study the atmospheric impact of SPEs over the period . The very largest SPEs were found to be the most important and caused atmospheric effects that lasted several months after the events. We present the short-and medium-term (days to a few months) atmospheric influence of the four largest SPEs in the past 45 years (August 1972;October 1989; as computed by WACCM3 and observed by satellite instruments. Polar mesospheric NO x (NO+NO 2 ) increased by over 50 ppbv and mesospheric ozone decreased by over 30% during these very large SPEs. Changes in HNO 3 , N 2 O 5 , ClONO 2 , HOCl, and ClO were indirectly caused by the very large SPEs in October-November 2003, were simulated by WACCM3, and previously measured by Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIPAS). WACCM3 output was also represented by sampling with the MIPAS averaging kernel for a more valid comparison. Although qualitatively similar, there are discrepancies between the model and measurement with WACCM3 predicted HNO 3 and ClONO 2 enhancements being smaller than measured and N 2 O 5 enhancements being larger than measured. The HOCl enhancements were fairly Correspondence to: C. H. Jackman (charles.h.jackman@nasa.gov) similar in amounts and temporal variation in WACCM3 and MIPAS. WACCM3 simulated ClO decreases below 50 km, whereas MIPAS mainly observed increases, a very perplexing difference. Upper stratospheric and lower mesospheric NO x increased by over 10 ppbv and was transported during polar night down to the middle stratosphere in several weeks past the SPE. The WACCM3 simulations confirmed the SH HALOE observations of enhanced NO x in September 2000 as a result of the July 2000 SPE and the NH SAGE II observations of enhanced NO 2 in March 1990 as a result of the October 1989 SPEs.

Solar forcing for CMIP6 (v3.2)

“…Direct measurements of SPE-caused OH and HO 2 enhancements have confirmed these early predictions (e.g., Damiani et al, 2008;Jackman et al, 2011Jackman et al, , 2014). Other observations of increased H 2 O 2 and of chlorine-containing constituents HOCl (an increase; see von Jackman et al, 2008;Damiani et al, 2008Damiani et al, , 2012Funke et al, 2011) and HCl (a decrease; see Winkler et al, 2009;Damiani et al, 2012) support the SPE-caused HO x enhancement theory. Since HO x constituents have relatively short lifetimes (hours), these SPE-enhanced species have only a short-term impact on ozone.…”

“…The ozone response due to very large SPEs is fairly rapid and substantial and has been observed during and after numerous events to date (e.g., Weeks et al, 1972;Heath et al, 1977;McPeters et al, 1981;Thomas et al, 1983;Solomon et al, 1982;McPeters and Jackman, 1985;Jackman et al, 1990Jackman et al, , 1995Jackman et al, , 2001Jackman et al, , 2005bJackman et al, , 2008Jackman et al, , 2011Jackman et al, , 2014 Decreases in mesospheric and upper stratospheric ozone are mostly caused by SPE-induced HO x increases, which were predicted to occur over 42 years ago (e.g., see Swider and Keneshea, 1973). Direct measurements of SPE-caused OH and HO 2 enhancements have confirmed these early predictions (e.g., Damiani et al, 2008;Jackman et al, 2011Jackman et al, , 2014).…”

Solar Influence on Global and Regional Climates

“…These nitrates are seen to migrate downwards over time (Siskind et al 2000;Funke et al 2005), resulting in catalytic destruction of stratospheric ozone (Callis et al 2000). Large SEP events generate considerable transient polar ozone depletions, which persist in winter until UV irradiance of the polar stratosphere resumes (Jackman et al 2006(Jackman et al , 2008Randall et al 2005Randall et al , 2007. Recently, Seppälä et al (2009) reported changes in polar surface temperatures which they associate with large SEP events.…”

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

“…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. (López-Puertas et al, 2005b;von Clarmann et al, 2005;Orsolini et al, 2009;Verronen et al, 2008;Funke et al, 2008;Jackman et al, 2008;Winkler et al, 2009;Verronen et al, 2011;Winkler et al, 2011;Funke et al, 2011;Damiani et al, 2012).…”

“…However, atmospheric models using the parameterisation based on Solomon et al (1981) significantly underestimate the amount of HNO 3 produced compared to observations (e.g. Jackman et al, 2008;Funke et al, 2011).…”