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Identification of the temperature gradient instability as the source of decameter‐scale ionospheric irregularities on plasmapause field lines
Author(s) -
Greenwald Raymond A.,
Oksavik Kjellmar,
Erickson Philip J.,
Lind Frank D.,
Ruohoniemi J. Michael,
Baker Joseph B. H.,
Gjerloev Jesper W.
Publication year - 2006
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2006gl026581
Subject(s) - ionosphere , plasmasphere , radar , geophysics , millstone hill , f region , instability , geology , incoherent scatter , physics , plasma , magnetosphere , telecommunications , quantum mechanics , computer science , mechanics
Recent observations with the new mid‐latitude SuperDARN HF radar located at Wallops Island, Virginia have identified a class of ionospheric irregularities that is prevalent in the nightside sub‐auroral ionosphere under low‐to‐moderate Kp conditions. These irregularities can be observed for many hours and generally exhibit very low Doppler velocities. A recent collaborative experiment using the Wallops radar and the Millstone Hill incoherent scatter radar has determined that these irregularities are located at the ionospheric footprint of the plasmapause and in a region of opposed electron density and electron temperature gradients. We conclude that the irregularities are produced by the temperature gradient instability (TGI) or by turbulent cascade from primary irregularity structures produced from this instability. This is the first experimental confirmation that the TGI is effective in producing decameter‐scale ionospheric irregularities.