Relation between Lower Ionospheric Electron Density Profiles and Cosmic Noise Absorption during Auroral Zone Disturbances

Abstract

Eight rockets among a total of twenty-one rocket experiments by the 12th, 13th and 14th Japanese Antarctic Research Expedition parties were launched during auroral disturbances at night at Syowa Station, Antarctica between 1971 and 1973. The electron density profiles in the lower ionosphere between about 50km and 130km under various disturbed conditions were obtained by rocket-borne radio frequency probes and electrostatic probes.
The collision frequency profile is derived from the electron density profiles and cosmic noise absorption measurements. There exists a maximum absorption layer in the region between 75km and 85km, and this location of the layer is not strongly dependent on the magnitude of the ionospheric disturbance. An increase in the electron density, especially in the D and E region between about 75km and 110km has a good correlation with cosmic noise absorption; the following empirical formulae are obtained from the observational results:
Δn_e=exp(0.205x+4.67),
h_m=-2x+100,
where Δn_e(cm^-3) is the maximum increment of the electron density from the quiet level, h_m(km) is the height of the maximum increment of the electron density and x(dB) is the cosmic noise absorption.