Ionization of the polar atmosphere by relyativistic electrons during October-November 2003 and changes in chemical composition: 3D model simulations

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Polar regions are the arears where we can see a strong manifestation of atmosphere-magnitosphere inter-
actions. Such interactions often occur via energetic particle influence: solar protons and relyativistic electrons
precipitating from radiation belts during geomagnetic storms. Energetic particles can penetrate below 100 km
into the polar atmosphere sometimes reaching the stratospheric levels wasting its energy and causing strong
ionization (each 35 eV gives one pair of ions). It was shown by the theory (and supported by observations)
that the ionization induced by the particles leads to additional production of NOx and HOx chemical com-
pounds destroying ozone in catalytic cycles. Then such produced by the paticles amounts of NOx can be
transported downlrroad in presence of the steady polar vortex. One of the strongest geomagnetic storms by a
stro oggoSolar Proton Eevent (SPE) occured in October-November 2003. The response of atmospheric chemical
composition in both polar regions was studied with CAO_3D photochemical-transport model /Krivolutsky et
al., 2002/.The wind components used in the advection scheme of the photochemical model have been taken from
GCM /CAO/COMMA; Krivolutsky et al., 2006/. GCM was also used to investigate changes in circulation and
temperature caused by particle-induced ozone variations. In order to calculate ionization rates induced by rely-
ativistic electrons and solar protons during late October-November, corresponding proton and electron fluxes
in different energetic canals from GOES-10/11 and POES-15/16 have been used. The Atmospheric Ionization
Module Osnabruck - AMOS /Wissig and Kallenrode, 2009/ was used to calculate 3D fields of ionization rates
separately from electrons and protons. Photochemical simulaions showed that Northern and Southern polar
regions have different response in chemical composition to energetic particles during the period of geomagnetic
storms in October-November 2003. Such difference is the result of the two factors: polar cap expansion during
the geomagnetic storm and the effect of transport. So the resuls illustrates how polar regions can influence
chemical composition and dynamics of the lower latitudes. This work was supported by Russian Science Fouda-
tion for Basic Research (grand № 09-05-009949) and by contract № 1-6-08 under Russian Sub-Program “Reseach
and Investigation of Antarctica”.