In a recent Journal of Geophysical Research paper, S.M. Päivärinta and colleagues investigated the effects of solar proton events (SPEs) and sudden stratospheric warmings (SSWs) on odd nitrogen and ozone in the polar middle atmosphere using observations from ACE-FTS, MLS/Aura and SABER/TIMED. Considering three different winters, 2005 (with an SPE), 2009 (with an SSW), and 2012 (with SPEs and SSW), they found that NOx increases after both SPEs and SSWs by up to a factor of 25 between 40-90km. As a result of the enhanced NOx concentrations, strong ozone depletion occurred. Find the full abstract here.