Composition changes after the "Halloween" solar proton event: the High-Energy Particle Precipitation in the Atmosphere (HEPPA) model versus MIPAS data intercomparison study

Abstract

We have compared composition changes of NO, NO<sub>2</sub>, H<sub>2</sub>O<sub>2</sub>, O<sub>3</sub>, N<sub>2</sub>O, HNO<sub>3</sub>, N<sub>2</sub>O<sub>5</sub>, HNO<sub>4</sub>, ClO, HOCl, and ClONO<sub>2</sub> as observed by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat in the aftermath of the "Halloween" solar proton event (SPE) in October/November 2003 at 25–0.01 hPa in the Northern Hemisphere (40–90° N) and simulations performed by the following atmospheric models: the Bremen 2d Model (B2dM) and Bremen 3d Chemical Transport Model (B3dCTM), the Central Aerological Observatory (CAO) model, FinROSE, the Hamburg Model of the Neutral and Ionized Atmosphere (HAMMONIA), the Karlsruhe Simulation Model of the Middle Atmosphere (KASIMA), the ECHAM5/MESSy Atmospheric Chemistry (EMAC) model, the modeling tool for SOlar Climate Ozone Links studies (SOCOL and SOCOLi), and the Whole Atmosphere Community Climate Model (WACCM4). The large number of participating models allowed for an evaluation of the overall ability of atmospheric models to reproduce observed atmospheric perturbations generated by SPEs, particularly with respect to NO<sub>y</sub> and ozone changes. We have further assessed the meteorological conditions and their implications on the chemical response to the SPE in both the models and observations by comparing temperature and tracer (CH<sub>4</sub> and CO) fields. <br><br> Simulated SPE-induced ozone losses agree on average within 5% with the observations. Simulated oy enhancements around 1 hPa, however, are typically 30% higher than indicated by the observations which can be partly attributed to an overestimation of simulated electron-induced ionization. The analysis of the observed and modeled NO<sub>y</sub> partitioning in the aftermath of the SPE has demonstrated the need to implement additional ion chemistry (HNO<sub>3</sub> formation via ion-ion recombination and water cluster ions) into the chemical schemes. An overestimation of observed H<sub>2</sub>O enhancements by all models hints at an underestimation of the OH/HO<sub>2</sub> ratio in the upper polar stratosphere during the SPE. The analysis of chlorine species perturbations has shown that the encountered differences between models and observations, particularly the underestimation of observed ClONO<sub>2</sub> enhancements, are related to a smaller availability of ClO in the polar night region already before the SPE. In general, the intercomparison has demonstrated that differences in the meteorology and/or initial state of the atmosphere in the simulations causes a relevant variability of the model results, even on a short timescale of only a few days

Chlorine in the stratosphere

“…After the SPE around Halloween 2003, ClO averaged over the polar cap, the major parts of which were still illuminated, was reported by these authors to increase after the proton forcing, except for regions poleward of 70° N, where the polar vortex was dark. In these regions a ClO decrease was observed (Funke et al, 2011). The sudden increase of HOCl during this SPE, which also was observed with MIPAS data, did not only confirm SPE-induced chlorine activation but also was the first experimental evidence of accelerated HO x chemistry during an SPE.…”

What is the solar influence on climate? Overview of activities during CAWSES-II

“…While the impact on stratospheric ozone levels (from SPEs only) was found to be long lasting and significant (>10% stratospheric ozone loss up to 5 months http://www.progearthplanetsci.com/content/1/1/24 past the event), the simulated long-term impacts on polar annual mean total ozone and temperature were not significant. Funke et al (2011) performed a comparison between satellite observations of atmospheric chemistry response to the 2003 October-November SPEs and the responses of nine different chemistry-climate models and chemistry-transport/general circulation models within the SOLARIS-HEPPA -Solar Influences for SPARC Model-Measurement Intercomparison (MMI) community effort. Overall, the models were found to reproduce the observed ozone loss reasonably well, but issues were identified regarding the used ionisation rates for the proton forcing in the models as well as the need to implement additional ion chemistry into the models' chemical schemes.…”

Influence of the Precipitating Energetic Particles on Atmospheric Chemistry and Climate

“…The enhancement of NO in the auroral zone has been observed by SNOE measurements . NO x and HO x enhancement in the mesosphere and stratosphere due to in situ ionization was detected by satellite measurements mostly during powerful precipitation events (e.g., López-Puertas et al 2005;Seppälä et al 2007b;Damiani et al 2008;Funke et al 2011;Verronen et al 2011). The enhancement of NO x in the stratosphere after substantial geomagnetic perturbation was detected by many groups (e.g., Callis et al 1998;Siskind et al 2000;Randall et al 2007;Clilverd et al 2009).…”

“…The production of NO x and HO x by GCR has not yet been confirmed observationally due to a rather small magnitude of the enhancement in the polar upper troposphere/lower stratosphere (UTLS) region, where the effects of GCR should be the most pronounced. The ozone depletion in the polar mesosphere and stratosphere after intensive SPE was observed by different satellite instruments Seppälä et al 2007b;Funke et al 2011). Significant correlation of the surface air temperature with the level of geomagnetic activity, which is represented by the Ap index, was discovered in the reanalysis data by Seppälä et al (2009).…”

“…A large number of simulations of the atmospheric changes caused by SPE have been performed using models of different complexity (see Jackman et al 2008and references therein, Reddmann et al 2010) and a successful reproduction of the main observed features have been recently reported by Funke et al (2011).…”