3:00 PM - 3:15 PM
[AAS10-06] Significance of ionic reactions in the temporal evolution of concentrations of chemical species in the stratosphere induced by “Halloween” solar proton event
Keywords:Solar proton event, box model, ionic reactions
Temporal evolution of concentrations of chemical species in the stratosphere induced by solar proton events has been observed (e.g., Funke et al., 2011). It has been shown that considering both neutral and ionic reactions is essential to understanding the observation particularly in the D-region, polar lower ionosphere (Verronen et al., 2016; Verronen et al.,2005). In order to investigate the significance of ionic reactions in the stratosphere caused by solar proton events, we developed a box model that incorporates a total of 752 reactions, including 147 neutral reactions and 605 ionic reactions. In this study, we simulated the temporal evolution of chemical species concentrations after the “Halloween event” occurred in 2003. We examined whether trends observed in the MIPAS observational data (analytical data from IMK - Karlsruhe Institute of Technology/IAA - Institute of Astrophysics of Andalusia) could be produced in the model results. We then examined the significance of ionic reactions by comparing simulations with and without ionic reactions.
In Fig. 1, we present the area-weighted averages (60–90°N) of simulated and observed relative ozone changes at an altitude of 50 km after the Halloween event. The simulation with 752 reactions, including ionic reactions, shows a rapid decrease and subsequent recovery. It is in qualitative agreement with the MIPAS observational data. However, with only 147 neutral reactions, the model was insufficient to explain the trends observed in the ozone changes. Our results also suggest the importance of the following three reactions: (1) NO+O3→NO2+O2, (2) O3+OH→O2+HO2, and (3) O3+O2-→O2+O3- after the ionization and dissociation of nitrogen and oxygen molecules due to high-energy protons and the successive reactions.
In this presentation, we will also discuss the temporal evolution of reactive nitrogen oxides and the results in other altitudes.
Reference
1) B. Funke , et al., “Composition changes after the“Halloween”solar proton event: the High Energy Particle Precipitation in the Atmosphere (HEPPA) model versus MIPAS data intercomparison study”, Atmos. Chem. Phys. 11, 9089–9139, 2011.
2) P. T. Verronen, et al., “WACCM-D - Whole Atmosphere Community Climate Model with D-region ion chemistry”, J. Adv. Model. Earth Syst. 8, 954–975, 2016.
3) P. T. Verronen, et al., “Diurnal variation of ozone depletion during the October-November 2003 solar proton events”, J. Geophys. Res., 110, A09S32, 2005.
In Fig. 1, we present the area-weighted averages (60–90°N) of simulated and observed relative ozone changes at an altitude of 50 km after the Halloween event. The simulation with 752 reactions, including ionic reactions, shows a rapid decrease and subsequent recovery. It is in qualitative agreement with the MIPAS observational data. However, with only 147 neutral reactions, the model was insufficient to explain the trends observed in the ozone changes. Our results also suggest the importance of the following three reactions: (1) NO+O3→NO2+O2, (2) O3+OH→O2+HO2, and (3) O3+O2-→O2+O3- after the ionization and dissociation of nitrogen and oxygen molecules due to high-energy protons and the successive reactions.
In this presentation, we will also discuss the temporal evolution of reactive nitrogen oxides and the results in other altitudes.
Reference
1) B. Funke , et al., “Composition changes after the“Halloween”solar proton event: the High Energy Particle Precipitation in the Atmosphere (HEPPA) model versus MIPAS data intercomparison study”, Atmos. Chem. Phys. 11, 9089–9139, 2011.
2) P. T. Verronen, et al., “WACCM-D - Whole Atmosphere Community Climate Model with D-region ion chemistry”, J. Adv. Model. Earth Syst. 8, 954–975, 2016.
3) P. T. Verronen, et al., “Diurnal variation of ozone depletion during the October-November 2003 solar proton events”, J. Geophys. Res., 110, A09S32, 2005.