Modeling the Effects of Solar Proton Events on Middle Atmosphere

Pekka Verronen1, Erkki Kyrölä1, Esa Turunen2, and Thomas Ulich2

1Finnish Meteorological Institute, Geophysical Research, P.O. Box 503, FIN-00101 Helsinki, Finland
2Sodankylä Geophysical Observatory, Tähteläntie 112, FIN-99600 Sodankylä, Finland


The ionization by solar UV-radiation and energetic particle precipitation causes variation in upper atmosphere constituent concentrations. Ionization and chemical reactions lead to a production of odd nitrogen in the mesosphere, which in turn affects the ozone balance. Under polar night conditions the nitric oxides are long lived and may be carried down into the lower atmosphere, where they can participate in destruction of stratospheric ozone.

Three European satellite missions, Envisat-1, Ørsted, and Odin, will be launched in next two years. Together with the EISCAT incoherent scatter radars and a network of other ground measurements they will provide a so far unique possibility to address this scientific problem in the auroral region.

The Sodankylä Geophysical Observatory (SGO) and the Finnish Meteorological Institute (FMI) are developing a detailed chemical model on the base of the Sodankylä Ion Chemistry Model (SIC) in order to utilize these new data sets and study the effects of solar radiation and energetic particles on mesospheric and stratospheric concentrations. The purpose is to model in detail the process chain starting from ionization in the mesosphere to the destruction of ozone in the stratosphere.

In order to establish the magnitude of the effects of proton events on middle atmosphere we have added relevant neutral chemistry into the SIC-model and modeled some proton events using a variety of available measurement data.

We will present our project, the latest development of our model, and the preliminary modeling studies.