Interpretation of equatorial electrojet irregularities observed with a broad beam HF zenithal radar

Abstract

In comparison with VHF, few HF radar observations of the electrojet have been performed. 1141

On equatorial geophysics studies: a review on the IGRGEA results during the last decade

“…In addition scattering arises from specific oblique propagation around the E layer peak whereby the type I irregularity mode is evidenced (Fig. 3 in Farges et al, 1999). Similar echoes have also been obtained in the same region by the Jicamarca radar (Kudeki and Fawcett, 1993).…”

The São Luís 30 MHz coherent scatter ionospheric radar: System description and initial results

“…Ionospheric E and F region irregularity characteristics have been studied using HF radars [ Blanc et al , 1996; Farges et al , 1999; Haldoupis , 1996; Tsunoda , 1994] and VHF radar [ Balsley , 1969; Fejer et al , 1975a, 1975b; Farley et al , 1970; Patra et al , 1995; Tsunoda and Ecklund , 2000; Swartz , 1997; Hysell et al , 1997; Hysell and Burcham , 1998, 2002; Abdu et al , 2002]. Irregularities and electric fields in the equatorial electrojet have been studied extensively by several authors [e.g., Balsley , 1973; Fejer et al , 1975a, 1975b; Fejer and Kelley , 1980; Kudeki et al , 1982; Farley , 1985; Pfaff et al , 1987; Swartz and Farley , 1994; Ragharavao et al , 2002] and since their discovery by Balsley [1964], the so‐called 150 km echoes have also been studied by many researchers [ Royrvik , 1982; Kudeki and Fawcett , 1993; Blanc et al , 1996; Hysell et al , 1997; Tsunoda , 1994; Farges et al , 1999; Tsunoda and Ecklund , 2000]. As they affect telecommunication and navigation systems, plasma irregularities associated with equatorial spread F phenomena have been studied intently for many years [ Farley et al , 1970; Woodman and La Hoz , 1976; Sobral et al , 1980; Kelley , 1985; Fejer , 1997; Fejer et al , 1999; Aarons , 1999; Hysell and Burcham , 1998, 2002; Abdu et al , 2000; Abdu , 2001; Musman et al , 1997].…”

Observation of coherent echoes with narrow spectra near 150 km altitude during daytime away from the dip equator

“…The 150‐km echoes have now been reported from almost all HF and VHF radars operating in the vicinity of the dip‐equator, that is: the Pohnpei radar in the Pacific [ Kudeki et al , 1998], the HF radar at Sao‐Luis in Brazil [ de Paula and Hysell , 2004], and the HF radar on the Ivory Coast in Africa [ Blanc et al , 1996] (although in this latter case the genuine 150‐km echoes were seen at a 180 km range because of the very low frequency that was being used [ Farges et al , 1999]). These echoes, however, have never been reported from any of the mid or low latitude VHF/HF radar locations.…”