DE1 observations of polar O{sup +} stream bulk parameters and comparison with a model of the centrifugally-accelerated polar wind

Journal Article · Tue Nov 15 04:00:00 EST 1994 · Geophysical Research Letters

DOI:https://doi.org/10.1029/94GL02340· OSTI ID:57019

Wing Ho, C; Horwitz, J L ^[1]; Moore, T E ^[2]

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1. Univ. of Alabama, Huntsville, AL (United States)
2. NASA/Marshall Space Flight Center, Huntsville, AL (United States)

A survey of bulk parameters of analyzable O{sup +} outward streams in the midlatitude (3-4.7 R{sub E} geocentric distance) polar cap magnetosphere is obtained from measurements by the Retarding Ion Mass Spectrometer (RIMS) aboard the Dynamics Explorer 1 (DE1) spacecraft. There is wide scatter in the obtained densities, but they do display discernible trends: the average O{sup +} density in these streams decreases from about 30 ions cm{sup {minus}3} at 3.5 R{sub E} to about 1 ion cm{sup {minus}3} at 4.6 R{sub E}. The streaming velocities are somewhat more defined, and their average increases from about 8 km s{sup {minus}1} at 3.5 R{sub E} to about 12 km s{sup {minus}1} at 4.6 R{sub E}. The outward ion flux increases by a factor of 4 with magnetic activity from K{sub p} = 2 to 5. The authors have further compared these observational trends with model profiles for the centrifugally-accelerated polar wind as recently described by Horwitz et al. The large outflow velocities observed can be understood in part as centrifugally-driven by convection with ionospheric electric field magnitudes of the order 50-70 mV m{sup {minus}1}, perhaps including plasma expansion effects. 13 refs., 3 figs.

• Sponsoring Organization: USDOE
• OSTI ID: 57019
• Journal Information: Geophysical Research Letters, Journal Name: Geophysical Research Letters Journal Issue: 23 Vol. 21; ISSN GPRLAJ; ISSN 0094-8276
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ACCELERATION
EARTH MAGNETOSPHERE
OXYGEN IONS
POLAR REGIONS
RADIATION STREAMING