Speaker
Description
Energetic electron precipitations (EEP) from the solar wind introduce reactive species such as NOx and HOx into the middle atmosphere, leading to ozone depletion and subsequent modifications of the radiative balance during winter. In the Northern Hemisphere, however, the dominant source of variability in the polar stratosphere arises from sudden stratospheric warmings (SSWs), which can mask the atmospheric response to EEP. To better isolate the particle effect, we evaluate the stratospheric response with respect to SSW onset dates using ERA5 reanalysis data. Our analysis shows that EEP not only modulates the occurrence frequency of SSWs, as previously reported, but also influences their strength and subsequent evolution. In particular, January warmings are sensitive to geomagnetic activity: under high EEP conditions, the events are weaker, and the polar vortex exhibits a faster recovery. In contrast, February SSWs appear less affected by EEP variability. These results highlight the importance of accounting for the timing of SSWs when assessing effects of precipitating particles on the wintertime stratosphere.
