First observations of detached equatorial ionospheric plasma depletions using OI 630.0 nm and OI 777.4 nm emissions nightglow imaging

摘要

Near-simultaneous all-sky (180 degrees field of view) observations of the OI 630.0 nm and OI 777.4 nm nightglow emissions are being carried out on a routine basis at "Laboratorio Nacional de Astrofisica (LNA)'', Brazopolis (22.5 degrees S, 45.6 degrees W; dip latitude 17.5 degrees S; altitude 1860 m), Brazil, since September 2002. The all-sky imaging observations of the OI 630.0 nm and OI 777.4 nm emissions, which arise from the dissociative recombination of O-2(+) ions and radiative recombination of O+ ions ( mainly), respectively, are used to monitor the morphology and dynamics of the equatorial F-region at the respective emission heights. In this paper we present and discuss the first observations showing detached equatorial F-region plasma depletions or bubbles. Three cases are presented from observations during the years 2002 and 2003. We suggest a possible mechanism for their generation.