Modeling Mesospheric Odd Nitrogen During the October 1989 SPE
with the detailed Sodankylä Ion-Neutral Chemistry Model
Pekka Verronen1, Esa Turunen2,
Thomas Ulich2, and Erkki Kyrölä1
1Finnish Meteorological Institute, Geophysical Research,
P.O. Box 503, FIN-00101 Helsinki, Finland
2Sodankylä Geophysical Observatory,
Tähteläntie 112, FIN-99600 Sodankylä, Finland
Abstract
Precipitation of energetic particles affects the chemical balance of the
middle atmosphere. It leads to enhanced production of some important
minor neutral constituents, such as NO and OH, which might affect the
ozone budget. Ion-neutral reactions play an important role in the
production of minor neutrals.
The Sodankylä Ion Chemistry (SIC) model was revised by combining
relevant neutral chemistry with ion chemistry and is now used to
investigate the effect of precipitation events on minor constituents,
including NO and ozone. The new model covers altitudes from 50 to 100 km
and can be used as steady-state or time-dependent model. At the moment SIC
includes over 400 chemical reactions and models the behavior of 55 ion and
9 neutral species. The time-dependent model allows short-term variations
of these species to be followed, so that their response to observed
precipitation events or to sunrise/sunset effects can be studied in
detail.
We have modeled the behavior of odd nitrogen above Tromsø
(69.59°N 19.23°E) during the October 1989 solar proton event. Our
results show how the intense particle ionization significantly increases
the amount of atomic nitrogen and affects the
N(