Papers on Ionosphere and Upper Atmosphere:Regular Papers
Observations of traveling ionospheric disturbances with a satellite-beacon radio interferometer: Seasonal and local time behavior
Article first published online: 20 SEP 2012
Copyright 1995 by the American Geophysical Union.
Journal of Geophysical Research: Space Physics (1978–2012)
Volume 100, Issue A2, pages 1653–1665, 1 February 1995
How to Cite
1995), Observations of traveling ionospheric disturbances with a satellite-beacon radio interferometer: Seasonal and local time behavior, J. Geophys. Res., 100(A2), 1653–1665, doi:10.1029/94JA02663., , , and (
- Issue published online: 20 SEP 2012
- Article first published online: 20 SEP 2012
- Manuscript Accepted: 30 SEP 1994
- Manuscript Received: 6 APR 1994
We have operated a very long baseline interferometer array at a northern midlatitude site, illuminated by VHF radio beacons from two geosynchronous satellites, quasi-continuously for over a year. The array can detect and measure the trace velocity of traveling ionospheric disturbances (TIDs) via their signatures in the line-of-sight total electron content (TEC). The system noise level is of the order of 1013 m−2 in the TEC, so that even very weak perturbations can be studied. We have used the year-long TID detection/velocimetry data set to describe local time and seasonal dependences of the wave parameters. The most striking finding is that the preferred azimuths of TIDs in the data set tend to belong to either of two modes: The first mode, strongest at midday and in the early afternoon, particularly around winter equinox, propagates southward. The second mode, strongest in the evening, especially during summer solstice through autumn equinox, propagates west-northwestward. The two modes are disposed in local time such as to suggest the agency of clockwise rotation of the TID preferred azimuths versus time, as expected by wind filtering in the thermospheric diurnal tide. However, there is a gap between the two modes' azimuth bands. Moreover, the two modes exist in all trace-speed quartiles of the data set TIDs, a finding which is at variance with the hypothesis of wind filtering being the primary explanation of these modes.