Radar measurements of gravity waves in the ionosphere

Abstract

Some characteristic parameters of gravity waves at D and E region heights such as amplitude, frequency spectrum and spatial properties can and have been measured by means of VHF radars. One of the techniques makes use of ionization trails produced by meteors as tracers of the neutral atmosphere motions in the region from 80 to 100 km. A recently developed technique at the Jicamarca Radio Observatory uses background enhanced fluctuations in the dielectric properties of the medium as tracers of the neutral motions in the region between 60 and 85 km. Profiles of the velocity field can be obtained continuously with a time resolution of the order of a minute allowing observations of gravity waves from its lowest periods, of the order of a few minutes, to tidal periods. Gravity waves in the lower F region have also been detected using incoherent scatter techniques. The methods, potential and limitations of the above mentioned techniques are reviewed as well as some of the results obtained.