The Solar Proton Events in 2012 as Observed by MIPAS
von Clarmann, Thomas1; Funke, Bernd2; Lopez-Puertas, Manuel2; Kellmann, Sylvia1; Linden, Andrea1; Stiller, Gabriele1; Jackman, Charles H.3; Harvey, V. L.4

During the solar proton events on 23-30 January and 7-15 March 2012 the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) on Envisat provided measurements of atmospheric temperature and composition (O3, CO, CH4, NO2, NO, HNO3, N2O5, HNO4, ClONO2, N2O, and ClO are relevant in this context) with global coverage. In the Northern hemisphere, the January SPE started at the end of a polar stratospheric warming period. The SPE effect was superimposed by large-scale subsidence of mesospheric NOx-rich air. This partly masked direct chemical SPE effects. SPE-induced NOx increases by 5, 20, 50 and 100 ppbv at altitudes of 50, 57, 60 and 70 km, respectively, were observed during the January SPE, and by 2, 5, 10, 20, 30, and 35 ppbv at altitudes of 47, 50, 53, 60, 63 and 66 km, respectively, during the SPE in March. SPE-related ozone loss is clearly observed in the mesosphere, particularly in the tertiary ozone maximum. A sudden short-term HNO4 increase immediately after the January SPE hints at SPE-triggered HOx chemistry. In the Southern Hemisphere, a large NOx response is observed (increases by 2, 5, 10, 20, and 30 ppbv at 52, 56, 59, 63 and 70 km in January and 2, 5, 10, 30, 35 ppbv at 47, 50, 53, 60, 63 and 66 km in March), while the effect on other species seems much less pronounced than in the Northern Hemisphere. SPE-related destruction of mesospheric ozone in the Southern Hemisphere was much more pronounced after the March SPE than the January SPE but in both cases ozone recovered within about a day.