EISCAT observations of topside ionospheric ion outflows during auroral activity: Revisited

Journal Article · Sun Mar 01 04:00:00 EST 1992 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/91JA02438· OSTI ID:5595250

Wahlund, J E; Opgenoorth, H J ^[1]; Haeggstroem, I ^[2]; Winser, K J ^[3]; Jones, G O.L. ^[4]

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1. Swedish Inst. of Space Physics, Uppsala (Sweden)
2. Swedish Inst. of Space Physics, Kiruna (Sweden)
3. Royal Coll. of Surgeons, Dublin (Ireland)
4. Univ. Coll. of Wales, Aberystwyth (United Kingdom)

New EISCAT observations of large field-aligned bulk ion outflows from the topside ionosphere during auroral activity are presented. The ions (mainly O{sup +}) start their outflows from a variable altitude and may reach field-aligned outward velocities of up to 1,500 m s{sup {minus}1} in the altitude region 900-1,500 km. The observed ion fluxes are about a factor of 10 larger than previously observed reaching 2 {times} 10{sup 14} m{sup {minus}2} s{sup {minus}1}, and in some cases is nonconstant with altitude. Two different types of ion outflows have been identified. The first type is related to periods of strong perpendicular electric fields, enhanced and anisotropic ion temperatures, and low electron densities below 300 km, indicating small amounts of auroral precipitation. The second type is related to auroral arcs and enhanced electron temperatures. The exact mechanism causing the ion outflows is still not yet understood, but additional mechanism other than thermal expansion are required to explain the observations presented here.

• OSTI ID: 5595250
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 97:A3; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAE
AURORAL ZONES
CATIONS
CHARGED PARTICLES
CHARGED-PARTICLE PRECIPITATION
EARTH ATMOSPHERE
ELECTRIC FIELDS
ELECTRON DENSITY
ELECTRON TEMPERATURE
ION DRIFT
IONOSPHERE
IONS
OXYGEN IONS
PLANETARY IONOSPHERES
SATELLITES
VELOCITY