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Ann. Geophys., 18, 1210-1215, 2000
www.ann-geophys.net/18/1210/2000/
© European Geosciences Union 2000
First EISCAT measurement of electron-gas temperature in the artificially heated D-region ionosphere
A. Kero1, T. Bösinger1, P. Pollari1, E. Turunen2, and M. Rietveld3
1University of Oulu, Department of Physical Sciences, FIN-90401 Oulu, Finland
2Geophysical Observatory, FIN-9960 Sodankylä, Finland
3EISCAT, 9027 Ramfjordbotn, Norway; also at Max-Planck-Institut für Aeronomie, D-37191 Katlenburg-Lindau, Germany
Abstract. The ionospheric electron gas can be heated
artificially by a powerful radio wave. According to our modeling, the maximum
effect of this heating occurs in the D-region where the electron temperature can
increase by a factor of ten. Ionospheric plasma parameters such as Ne, Te
and Ti are measured by EISCAT incoherent scatter radar on a
routine basis. However, in the D-region the incoherent scatter echo is very weak
because of the low electron density. Moreover, the incoherent scatter spectrum
from the D-region is of Lorentzian shape which gives less information than the
spectrum from the E- and F-regions. These make EISCAT measurements in the
D-region difficult. A combined EISCAT VHF-radar and heating experiment was
carried out in November 1998 with the aim to measure the electron temperature
increase due to heating. In the experiment the heater was switched on/off at 5
minute intervals and the integration time of the radar was chosen synchronously
with the heating cycle. A systematic difference in the measured autocorrelation
functions was found between heated and unheated periods.
Key words: Ionosphere (active experiments; plasma
temperature and density; wave propagation)
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