Radar observations of the onset of current driven instabilities in the topside ionosphere

Journal Article · Mon Feb 01 04:00:00 EST 1988 · Geophys. Res. Lett.; (United States)

DOI:https://doi.org/10.1029/GL015i002p00160· OSTI ID:5311409

Foster, J C; del Pozo, C; Groves, K; Maurice, J

Millstone Hill radar spectra exhibit pronounced spectral asymmetries in the presence of field-aligned currents in the topside ionosphere. The enhanced, often intense, returns associated with the current-driven growth of the ion acoustic mode exhibit the characteristics of hard-target backscatter suggesting that many ''satellite echoes'' observed by UHF radars at high latitudes might be caused by this mechanism. A large current density (>100 ..mu..amp/m/sup 2/) is calculated for the conditions observed, consistent with that seen in intense earthward-directed current filaments. Our observations indicate that the ion acoustic mode grows toward instability with increasing altitude. Backscatter observed from the unstable region at higher altitudes is characteristically at the ion plasma frequency consistent with the unstable growth of the acoustic mode for large ratios of electron to ion temperature. copyright American Geophysical Union 1988

• Research Organization: Massachusetts Institute of Technology
• OSTI ID: 5311409
• Journal Information: Geophys. Res. Lett.; (United States), Journal Name: Geophys. Res. Lett.; (United States) Vol. 15:2; ISSN GPRLA
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BACKSCATTERING
CURRENT DENSITY
CURRENTS
EARTH ATMOSPHERE
ELECTRIC CURRENTS
ELECTRIC FIELDS
ELECTRON TEMPERATURE
INSTABILITY
ION ACOUSTIC WAVES
ION TEMPERATURE
ION WAVES
IONOSPHERE
MEASURING INSTRUMENTS
PLANETARY IONOSPHERES
PLASMA WAVES
RADAR
RANGE FINDERS
SCATTERING