Annales Geophysicae, Vol. 23, 1575-1583, 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, A. Senior³

¹Sodankylä Geophysical Observatory, Sodankylä, Finland,
²Finnish Meteorological Institute, Earth Observation, Helsinki, Finland,
³Dept. of Communication Systems, Lancaster University, Lancaster, U.K.

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.

© 2005 by the European Geosciences Union. Further electronic publication not allowed.

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