JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 110, A09S32, DOI:10.1029/2004JA010932, 2005

Diurnal variation of ozone depletion during the October-November 2003 solar proton events

P. T. Verronen1, A. Seppälä1, M. A. Clilverd2, C. J. Rodger3, E. Kyrölä1, C.-F. Enell4, Th.Ulich4, E. Turunen4

1Finnish Meteorological Institute, Earth Observation, Helsinki, Finland,
2British Antarctic Survey (NERC), Cambridge, U.K.,
3Dept. of Physics, University of Otago, Dunedin, New Zealand,
4Sodankylä Geophysical Observatory, Sodankylä, Finland


We have studied the short-term effect of the October-November 2003 series of solar proton events on the middle atmosphere. Using the proton flux measurements from the GOES-11 satellite as input, we modeled the effect of the precipitating particles between Oct 26 and Nov 7 with a 1-D ion and neutral chemistry model. Then we compared the results with ground-based radio propagation measurements as well as with NO2 and ozone profiles made by the GOMOS satellite instrument. The model and radio propagation observations show very good agreement, suggesting that the model is capturing the impact of solar protons on the ionosphere. The modeled and measured NO2 profiles agree at altitudes 40-70 km, particularly during times of large concentrations observed after the solar proton event onset. A comparison of the time series of ozone change shows a good agreement between the model and observations. The results demonstrate how order-of-magnitude enhancements in odd hydrogen and odd nitrogen concentrations lead to a short-term ozone depletion in the middle mesosphere and a persistent 20% decrease around the stratopause, respectively. The amount and altitude distribution of ozone depletion is found to depend not only on the flux and energy of the protons, but also on the diurnal cycle of ozone-depleting constituents.

© 2005 by the American Geophysical Union. Further electronic publication not allowed.

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