Response of Mesospheric HO2 and O3 to Large Solar Proton Events

Abstract

AbstractA lot of solar proton events (SPEs) have happened during the ongoing solar cycle 24 including extremely large events. Seven large SPEs from 2012 to 2017 were chosen to find the response of polar atmosphere to them. Three SPEs happened in 2012, and the other four SPEs happened in 2013, 2014, 2015, and 2017, respectively. The National Oceanic and Atmospheric Administration Geostationary Operational Environmental Satellites 13 proton observations were used to illustrate the proton flux toward the Earth during each SPE. These energetic protons are deposited in the middle and upper atmosphere and ionize the neutral atmosphere constituents and create radicals HOx (H, OH, and HO2). Enhancements in the upper atmospheric hydroperoxyl radical (HO2) of both polar regions of over 1 ppbv are found in the Aura Microwave Limb Sounder measurements immediately after some SPEs happened. The Microwave Limb Sounder observations of ozone (O3) show decreases of >10% in both polar middle and upper atmosphere for a few days with a peak value of >20–60% over 1–3 days. The compositions of HO2 and ozone for all the selected SPEs indicate that the polar ozone depletions during the SPEs in a way are the result of the HO2 enhancements.