UPPER ATMOSPHERE AS A MULTIPLY REFRACTIVE MEDIUM FOR NEUTRAL AIR MOTIONS

Under the influence of gravity and heat conduction four plane characteristic waves obliquely incident on a horizontally stratified atmosphere can propagate, two of them upward and the two other downward. The two pairs of characteristic waves are the well known acoustic gravity waves and the heat conduction waves. Molecular viscosity generates two further pairs of characteristic waves, the ordinary and the extraordinary viscosity waves. Ion drag and Coriolis force make the atmosphere anisotropic with respect to the characteristic waves. Their propagation characteristics for east to west and north to south propagation differ from each other. Some analytical solutions of the eigenvalues of these eight characteristic waves are given in this paper. Numerical calculations of the eigenvalues depending on the parameters of the thermosphere, on frequency, azimuth and on angle of incidence are presented and discussed in some detail. © 1969.