Open AccessOptical observations of the growth and day‐to‐day variability of equatorial plasma bubbles
Author(s) -
Makela J. J.,
Miller E. S.
Publication year - 2008
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2007ja012661
Subject(s) - ionosphere , observatory , airglow , atmospheric sciences , earth's magnetic field , wavelength , instability , geology , physics , geophysics , magnetic field , astrophysics , optics , quantum mechanics , mechanics
A new narrow‐field ionospheric imaging system, the Portable Ionospheric Camera and Small‐Scale Observatory, has been installed at the Cerro Tololo Inter‐American Observatory near La Serena, Chile (geographic 30.17°S, 289.19°E; geomagnetic 16.72°S, 0.42°E). We present observations of the naturally occurring nightglow emission at 630.0 nm on three consecutive nights demonstrating the day‐to‐day variability in the occurrence of equatorial plasma bubbles or depletions. On two nights, large‐scale undulations with a wavelength on the order of 300–600 km are observed in the emission regions magnetically connected to the bottomside of the equatorial F layer. We demonstrate that at each crest of these large‐scale waves, zero, one, or multiple depletions may grow. Thus, the presence of a large‐scale wave on the bottomside alone is not sufficient for irregularity growth. This variability is presumably due to the presence, or lack, of small‐scale seed waves or some other mechanism needed to increase the instability growth rate past the critical threshold.