Long-term Effects of the Variability of Solar UV Radiation on the Ion Chemistry of the Middle Atmosphere

Thomas Ulich1, Esa Turunen1, Pekka Verronen2, Erkki Kyrölä2

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


The solar UV radiation is the main ionising factor in the day-time upper mesosphere during quiet geophysical conditions. The UV radiation varies with the solar activity cycle. This variation is much stronger than the variability of the total solar irradiance or the variability of visible light. We use the detailed 55-ion Sodankylä Ion Chemistry (SIC) model in order to study the effects of changing UV input to the atmosphere. Using available UV data and models as input in the calculation of the ionisation balance, we compare the model results both with long-term data sets from ground based instruments, and with available satellite data.

To be presented in session: JSA45