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Annales Geophysicae An interactive open-access journal of the European Geosciences Union
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Volume 16, issue 7
Ann. Geophys., 16, 821–827, 1998
© European Geosciences Union 1998
Ann. Geophys., 16, 821–827, 1998
© European Geosciences Union 1998

  31 Jul 1998

31 Jul 1998

Incoherent scatter radar observations of AGW/TID events generated by the moving solar terminator

V. G. Galushko1, V. V. Paznukhov1, Y. M. Yampolski1, and J. C. Foster2 V. G. Galushko et al.
  • 1Institute of Radio Astronomy, National Academy of Sciences of Ukraine, Kharkov, Ukraine
  • 2MIT Haystack Observatory, Atmospheric Sciences Group, Westford, MA 01886, USA

Abstract. Observations of traveling ionospheric disturbances (TIDs) associated with atmospheric gravity waves (AGWs) generated by the moving solar terminator have been made with the Millstone Hill incoherent scatter radar. Three experiments near 1995 fall equinox measured the AGW/TID velocity and direction of motion. Spectral and cross-correlation analysis of the ionospheric density observations indicates that ST-generated AGWs/TIDs were observed during each experiment, with the more-pronounced effect occurring at sunrise. The strongest oscillations in the ionospheric parameters have periods of 1.5 to 2 hours. The group and phase velocities have been determined and show that the disturbances propagate in the horizontal plane perpendicular to the terminator with the group velocity of 300-400 m s-1 that corresponds to the ST speed at ionospheric heights. The high horizontal group velocity seems to contradict the accepted theory of AGW/TID propagation and indicates a need for additional investigation.

Key words. Ionosphere (wave propagation) · Meteorology and atmospheric dynamics (waves and tides)

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