HR: 1330h
AN: SM12A-1200    [PDF]
TI: Global Flow Rates of 15-eV to 33-keV Ions Away From Earth Near the Polar Satellite Apogee Versus Perigee
AU: * Lennartsson, O W
EM: lenn@mail.spasci.com
AF: Lockheed Martin ATC, L9-42, B255, 3251 Hanover St, Palo Alto, CA 94304 United States
AU: Collin, H L
EM: collin@mail.spasci.com
AF: Lockheed Martin ATC, L9-42, B255, 3251 Hanover St, Palo Alto, CA 94304 United States
AB: As previously reported, the southern hemispheric outflow rates of 15-eV to 33-keV ${\rm H}^{+}$, ${\rm O}^{+}$ and ${\rm He}^{+}$ ions observed 1996-98 by the TIMAS instrument on the Polar satellite about two ${\rm R}_{\rm E}$ geocentric distance, near perigee, are significantly less than rates observed by instruments at somewhat higher altitudes, especially the ${\rm H}^{+}$ rates. In this paper a comparison is made with TIMAS observations in the northern hemisphere, at 4-9 ${\rm R}_{\rm E}$, by scaling local flow densities along magnetic field lines in the combined IGRF-95 internal and Tsyganenko-95 external field models. The northern hemispheric outflow rates are indeed substantially greater within the given energy range, indicating continued acceleration of lower-energy ions above the Polar perigee altitude. Specifically, the northern rates for ${\rm O}^{+}$ and ${\rm He}^{+}$ ions are, respectively, about 3-5 and 6-10 times greater than their southern counterparts, the larger multiplier associated with summer season (April-September). In absolute numbers, in units of $10^{25}$ ${\rm s}^{-1}$, the northern outflow rates are in the range of 1-3 for the ${\rm O}^{+}$ and 0.3-1 for the ${\rm He}^{+}$, the larger numbers in the summer of 1998, about two years past solar minimum. The average Kp is about 2. The northern hemispheric outward flow rate of ${\rm H}^{+}$ ions is as much as 30-100 times greater than the southern counterpart, but that is largely due to solar origin ions with net flow away from the cusp region. Unlike the ionospheric ${\rm H}^{+}$ ions, the solar ions have much enhanced flow rate during the summer season (by almost a factor of three), presumably because the northern cusp is then tilted more toward the solar wind source.
DE: 2451 Particle acceleration
DE: 2704 Auroral phenomena (2407)
DE: 2724 Magnetopause, cusp, and boundary layers
DE: 2736 Magnetosphere/ionosphere interactions
DE: 2784 Solar wind/magnetosphere interactions
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting