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Ann. Geophys., 18, 1197-1209, 2000
www.ann-geophys.net/18/1197/2000/
© European Geosciences Union 2000
Irregular structures of the F layer at high latitudes during ionospheric heating
E. D. Tereshchenko1, M. O. Kozlova1, O. V. Evstafiev1, B. Z. Khudukon1, T. Nygrén2, M. Rietveld3, and A. Brekke4
1Polar Geophysical Institute, 15 Khalturina, 183010 Murmansk, Russia
2Department of Physical Sciences, University of Oulu, P.O. Box 3000 FIN-90401 Oulu, Finland
3EISCAT, N-9027 Ramfjordbon, Norway; also at Max-Planck-Institut für Aeronomie, D-37191 Katlenburg-Lindau, Germany
4Auroral Observatory, University of Tromsø N-9037 Tromsø Norway
Abstract. Results on heating the ionospheric F region
above Tromsø, Norway are presented. The ionosphere was monitored by satellite
tomography and amplitude scintillation methods as well as the EISCAT incoherent
scatter radar. No effect of heating was observed in the daytime. In the evening
and in the pre-midnight sector, noticeable tilts of the F region were observed
during heating periods. The tilts overlapped the heating cone, where the
electron density decreased and irregularities exceeding 10 km in size appeared.
Between the heating periods the F layer was restored to its horizontal shape.
The anisotropic parameters of small-scale irregularities with scale lengths of
hundreds of metres were also determined. It was found that the perpendicular
anisotropy points in the direction of F region plasma flow. In some cases the
results can be explained by assuming that the small-scale irregularities were
generated within the heating cone and drifted out of the heating region where
they were subsequently observed.
Key words: Ionosphere (active experiments; auroral
ionosphere; ionospheric irregularities)
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