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Seminar

Wednesday 07 February 2007, 1400-1500
C60 InfoLab21

Electron Heating in the D region and Mesosphere: A Progress Report

presented by Dr. Mike Rietveld from EISCAT, Tromso, Norway

Powerful radio-wave heating of electrons in the D region is one of the oldest known effects in ionospheric heating experiments.

It was used since the 1950s in the largely forgotten wave-interaction experiments for probing D region densities and collision frequencies. Since the 1980s the effect has been used to modulate ionospheric conductivities and currents, thereby radiating ELF and VLF waves. Since the late 1990s it was found that electron heating affects the strength of polar mesopsheric summer echoes, with both increases and decreases of the echo amplitude being possible.

Within the last few years even polar mesospheric winter echoes as low as 62 km can be modified, thus extending the diagnostic use of HF heating facilities. Nevertheless several gaps in our knowledge remain. For example measuring the effect of heating on the incoherently scattered signal from the D region has proved elusive, as has measuring the heating effect on riometers.

The theory, results, and ideas for future experiments related to these effects are discussed.