The ionospheric response to internal gravity waves: 1. TheF₂region response

The F2 region ionospheric response to individual internal gravity waves is calculated as a function of the azimuth of wave propagation. This response is shown to be highly anisotropic, with the anisotropy itself depending on the wave parameters, the geomagnetic dip, and the prevailing ionization density gradient. Because the ionization density gradient changes with time of day and season, the ionospheric response and hence the traveling ionospheric disturbance statistics themselves should exhibit corresponding diurnal and seasonal variations. The physical basis for the anisotropy of the ionospheric response is discussed.