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Abstract:
Electrons from the Earth’s magnetosphere precipitate into the thermosphere and mesosphere at high latitudes as a response to geomagnetic disturbances driven by the solar wind. Energetic electron precipitation (EEP) produces odd nitrogen (NOx) and odd hydrogen (HOx) oxides which catalytically destroy ozone and, thus, locally modulate the radiative and thermal balance. While EEP-HOx is short-living regardless of circumstances, EEP-NOx survives for months in darkness and descends to the polar stratosphere during the winter. Several studies, based on observations and models, have shown that EEP-induced ozone destruction affects the temperature and dynamics in the atmosphere, strengthening the stratospheric polar vortex, a westerly wind system surrounding the pole, in the northern winter hemisphere. Most observational studies on EEP effects, especially those concerning the polar vortex, have relied on reanalysis datasets which are mainly limited to stratospheric altitudes. Thus, observations of EEP effects on the atmosphere are still partly incomplete. In this work 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 mesosphere and stratosphere in the northern winter hemisphere in 2004-2022. In addition to examining the EEP effects in the northern winter stratosphere, we also study the variability of ozone, temperature, and zonal wind in the mesosphere. Satellite observations confirm the earlier found EEP effect on ozone and temperature on the polar vortex, as well as the modulation of the EEP effect on the polar vortex by planetary waves.
