Observations of tides and planetary waves in the atmosphere-ionosphere system

Abstract

Gravity, tidal, and planetary waves propagating from below represent sources of energy and momentum responsible for upward vertical coupling from “below” in the atmosphere-ionosphere system. A brief review of the observational evidence for tides and planetary waves in the neutral atmosphere (mesosphere and thermosphere) and, particularly, in the ionosphere, is given with a special emphasis on planetary wave type oscillations. Planetary waves of tropospheric origin detected in the middle atmosphere and lower ionosphere are unable to propagate efficiently deep into the thermosphere. However, planetary wave type oscillations are observed at the F2-region maximum heights. We must look for indirect ways for extending their influence upwards. Amplitudes of planetary wave oscillations in foF2 may be high (>1 MHz), with impact on predictions of radio wave propagation.