HR: 14:10h
AN: SM53C-03    [Abstracts]
TI: Causes of core ion upflow in the dayside cusp
AU: * Burchill, J K
EM: burchill@phys.ucalgary.ca
AF: University of Calgary, 2500 University Drive N.W., Calgary, AB T2N1N4 Canada
AU: Knudsen, D J
EM: knudsen@phys.ucalgary.ca
AF: University of Calgary, 2500 University Drive N.W., Calgary, AB T2N1N4 Canada
AU: Pfaff, R F
EM: robert.f.pfaff@nasa.gov
AF: NASA Goddard Space Flight Center, Code 696, Greenbelt, MD 20771 United States
AU: Clemmons, J H
EM: james.h.clemmons@aero.org
AF: Aerospace Corporation, P.O. Box 92957, Los Angeles, LA 90009 United States
AU: Steigies, C T
EM: steigies@physik.uni-kiel.de
AF: Christian-Albrechts-Universit„t zu Kiel, Olshausenstraáe 40, Kiel, D-24098 Germany
AU: Yeoman, T
EM: tim.yeoman@ion.le.ac.uk
AF: University of Leicester, University Road, Leicester, LE1 7RH United Kingdom
AB: We investigate the causes of low energy ($<20$ eV), or ``core'', ion upflows in Earth's cusp. The CUSP-2002 sounding rocket flew from Ny Alesund, Svalbard, on 14~December 2002, carrying a complement of instrumentation within the cusp to an altitude of 772~km. The Suprathermal Ion Imager (SII), a two-dimensional energy/arrival angle ion spectrograph, observed large $\rm{O}^+$ outflows within the cusp at altitudes as low as 500~km, while the ion kinetic temperature remained isotropic near 0.1--0.2 eV for the entire event. The upflow data exhibit clear transitions that correlate with the cusp boundary layer between closed and open magnetic field lines. We attempt to explain the time-evolution of these upflows by examining the effectiveness of the observed precipitating magnetosheath electron flux as a driver under the prevailing solar wind conditions. These observations provide quantitative information on the time-dependent response of polar ion upflow to soft electron precipitation, and offer an excellent opportunity for comparison with numerical models of ion outflow.
DE: 2704 Auroral phenomena (2407)
DE: 2724 Magnetopause, cusp, and boundary layers
DE: 2736 Magnetosphere/ionosphere interactions
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting