Effects of Energetic Particle Precipitations on Polar Middle Atmosphere Ozone: Direct and Indirect Mechanisms

The energetic particle precipitations (EPPs), which include solar proton events (SPEs) and energetic electron precipitations (EEPs), can significantly impact ozone levels in the polar middle atmosphere through two main mechanisms. One is the direct impact that the energetic protons can attend the mesosphere and catalyze ozone depletion through the ionized odd hydrogen. Another is the indirect impact that the downward branch of the residual circulation transports the ionized odd nitrogen to the stratosphere and causes a long‐term effect on ozone. In this study, we conduct case studies and statistical analyses of ozone observations from the Aura satellite to investigate these two mechanisms. For the direct impact, we find that the mesospheric ozone depletion during SPEs is more pronounced at higher geomagnetic latitudes and negatively correlates with the proton flux, while during EEPs the ozone depletion predominantly occurs in the geomagnetic latitude band of 60–70°. For the indirect impact, our results show no significant correlation between proton flux and stratospheric ozone depletion. However, when analyzing the vertical velocity of the residual circulation from the stratospheric ozone depletion trajectory, we find a notable SPE effect during winter. The SPEs modulate both horizontal and vertical circulation, which further influences ozone levels. This study further validates the physical link between the magnetosphere and atmosphere and promotes our understanding of the solar influence on Earth's climate.