Energetic particle induced intra-seasonal variability of ozone inside the Antarctic polar vortex observed in satellite data

Journal article, 2015

Measurements from 2002 to 2011 by three inde- pendent satellite instruments, namely MIPAS, SABER, and SMR on board the ENVISAT, TIMED, and Odin satellites are used to investigate the intra-seasonal variability of strato- spheric and mesospheric O3 volume mixing ratio (vmr) in- side the Antarctic polar vortex due to solar and geomagnetic activity. In this study, we individually analysed the relative O3 vmr variations between maximum and minimum condi- tions of a number of solar and geomagnetic indices (F10.7 cm solar radio flux, Ap index, ≥2 MeV electron flux). The indices are 26-day averages centred at 1 April, 1 May, and 1 June while O3 is based on 26-day running means from 1 April to 1 November at altitudes from 20 to 70 km. Dur- ing solar quiet time from 2005 to 2010, the composite of all three instruments reveals an apparent negative O3 sig- nal associated to the geomagnetic activity (Ap index) around 1 April, on average reaching amplitudes between −5 and −10 % of the respective O3 background. The O3 response exceeds the significance level of 95 % and propagates down- wards throughout the polar winter from the stratopause down to ∼ 25 km. These observed results are in good qualitative agreement with the O3 vmr pattern simulated with a three- dimensional chemistry-transport model, which includes par- ticle impact ionisation.