HR: 17:00h
AN: SM34A-05    [Abstracts]
TI: Average and Post-disturbance Pitch Angle Distributions Versus L From the CRRES Medium Electron A Instrument
AU: * Gannon, J
EM: gannonjl@colorado.edu
AF: University of Colorado- LASP, 1234 Innovation Dr, Boulder, CO 80303 United States
AU: Li, X
EM: lix@paracel.colorado.edu
AF: University of Colorado- LASP, 1234 Innovation Dr, Boulder, CO 80303 United States
AU: Heynderickx, D
EM: D.Heynderickx@oma.be
AF: Belgian Institute for Space Aeronomy, Ringlaan 3, Brussels, 000 Belgium
AB: The Medium Electron A instrument aboard CRRES (Combined Radiation and Release Experiment Satellite) provides differential flux measurements and pitch angle information for electrons in 16 energy channels ranging from 110 to 1633 keV. We extract pitch angle distributions for the inbound and outbound portion of each orbit, in 0.1 L bins from L=3.0 to 7.0, for individual energy channels using the data prior to March 24, 1991 (approximately half a year). These distributions are used to provide an average picture of electron pitch angle distributions versus L-shell. We use the countrate at 90 degrees and the average of the countrates at 135 and 45 degrees to classify each distribution as butterfly (defined as a $>$ 15% drop from 90 degrees to the average of 45 and 135 degrees), flattop (the count at 90 degrees is within the average of the count at 45 and 135 $\pm$15%) and pancake (all others). We define times of magnetic disturbance based on Dst levels during each orbit (i.e., Dst $<$ -30, -50 nT) and compare the relative contribution of flattop, butterfly, and pancake distributions during and after these orbits, at particular L-shells. Preliminary results show that, compared to the average profile versus L, a sharp increase in the percentage of butterfly distributions at L-shells beyond L=5.5 is observed post-disturbance. Of the non-pancake distributions at L-shells between L=3.0 to 5.0, flattop distributions contribute more than butterfly. In addition, the time evolution of post-disturbance distributions is presented in the form of a superimposed epoch analysis.
DE: 2720 Energetic particles, trapped
DE: 2730 Magnetosphere--inner
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting