Chemical and dynamical variability in the middle atmosphere related to energetic electron precipitation

Energetic electron precipitation (EEP) directly influences the high-latitude thermosphere and mesosphere. Precipitating electrons originate from the Earth’s magnetosphere and their precipitation to the atmosphere is driven by the solar wind. EEP produces odd nitrogen (NO_X) and odd hydrogen (HO_X) oxides which catalytically destroy ozone. During the winter, EEP-NO_X survives for months, which enables its descent to the polar stratosphere. Several studies, based on both observations and models, have shown that EEP-induced ozone destruction leads to changes in temperature and dynamics in the atmosphere which strengthen the stratospheric polar vortex, a westerly wind system surrounding the pole. However, most observational studies on EEP effects have relied on reanalysis datasets which are mainly limited to the stratospheric altitude. Thus, observations of EEP effects on the atmosphere are still partly incomplete. In this study we use the AURA/MLS satellite measurements of atmospheric variables and the POES/MEPED satellite measurements of precipitating electrons to study EEP-related interannual variability in chemical and dynamical properties of the northern winter mesosphere and stratosphere in 2004-2022. We confirm the earlier findings of EEP effects on ozone and temperature in the polar region and on the polar vortex in the stratosphere, and also examine the related variability in the northern winter mesosphere. Moreover, we confirm our recent results about the role of planetary waves in modulating the EEP effect on the polar vortex.