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Ann. Geophys., 23, 1575-1583, 2005
www.ann-geophys.net/23/1575/2005/
© European Geosciences Union 2005
Effects of D-region RF heating studied with the Sodankylä Ion Chemistry model
C.-F. Enell1, A. Kero1, E. Turunen1, Th. Ulich1, P. T. Verronen2, A. Seppälä2, S. Marple3, F. Honary3, and A. Senior3
1Sodankylä Geophysical Observatory, Finland
2Finnish Meteorological Institute, Helsinki, Finland
3Lancaster University, UK
Abstract. The upper mesosphere and lower thermosphere, or ionospheric D
region, is an atmospheric layer which is difficult to access
experimentally. A useful method that also has a large potential for
further studies is artificial heating of electrons by means of
powerful radio transmitters. Here we estimate the effect of D-region
heating for a few typical cases of high electron density – daylight, typical auroral electron precipitation, and a solar proton
event – by coupling a model of RF electron heating to the
Sodankylä Ion Chemistry (SIC) model. The predicted effects are among others an
increase in the ratio of the concentration of negative ions to that
of free electrons, and an increase in the absorption of cosmic noise
as measured by riometers. For the model runs presented in this
paper we have calculated the absorption for the frequency (38.2MHz)
of the IRIS imaging riometer in Kilpisjärvi,
Finland, as observing the ionosphere above the EISCAT Heater in
Tromsø, Norway. The predicted enhancements of the absorption are
0.2–0.8dB, an effect which is clearly detectable.
Keywords. Ionosphere (Active experiments; Ion chemistry
and composition; Wave propagation)
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