Observations of electron density and collision frequency during polar radio blackout conditions

Relation between lower ionospheric electron density profiles and cosmic noise absorption during auroral zone disturbances.

“…The electron density profiles in the D and E region can be measured by various techniques such as a low frequency sounder (WATTS, 1958;SHELLMAN, 1970;WAKAI, 1971), the cross-modulation method (HOLT et al, 1962), partial reflection method (BELROSE and BURKE, 1964;HAUG, 1966;BELROSE et al, 1972), riometer observation (PARTHASARATHY et al, 1963;LERFALD et al, 1964), radio wave absorption measurements (ELLING, 1974), incoherent scatter radar (BANKS et al, 1974), phase measurement of VLF propagation (RINNERT, 1973), and VHF propagation (WATKINS and ESSEX, 1973). Also, the direct measurement of the ionosphere by using sounding rocket is a powerful method (JESPERSEN et al, 1964(JESPERSEN et al, , 1966MECHTLY and SMITH, 1970;SECHRIST, 1970;DERBLOM and LADELL, 1973).…”

Retrieval of mesospheric electron densities using an optimal estimation inverse method

“…The possibility that Ae=Ao(z) is derived from signals contaminated by o -vertical re ections has been suggested (e.g. Holt et al, 1961;Belrose and Burke, 1964;Belrose, 1970). Other researchers have focused upon the possibility that the Fresnel re ection model used to obtain the Re=Ro(z) proÿle is insu ciently realistic to account for the physics of pulse ionosphere interactions.…”