HR: 12:05h
AN: SM51E-08    [PDF]
TI: MAXIS Balloon Observations of Electron Microburst Precipitation
AU: * Millan, R M
EM: Robyn.Millan@dartmouth.edu
AF: Dartmouth College, Department of Physics and Astronomy 6127 Wilder Lab, Hanover, NH 03755
AU: Hunter, A E
EM: Andrew.E.Hunter@dartmouth.edu
AF: Dartmouth College, Department of Physics and Astronomy 6127 Wilder Lab, Hanover, NH 03755
AU: McCarthy, M P
EM: McCarthy@geophys.washington.edu
AF: University of Washington, Department of Earth and Space Sciences, Seattle, WA 98195
AU: Lin, R P
EM: rlin@ssl.berkeley.edu
AF: U. C. Space Sciences Lab, University of California, Berkeley, Berkeley, CA 93923
AU: Smith, D M
EM: dsmith@ssl.berkeley.edu
AF: U. C. Space Sciences Lab, University of California, Berkeley, Berkeley, CA 93923
AB: Quantifying and understanding losses is an integral part of understanding relativistic electron variability in the radiation belts. SAMPEX observations indicate that electron microburst precipitation is a major loss mechanism during active periods; the loss of relativistic electrons during a six hour period due to microburst precipitation was recently estimated to be comparable to the total number of trapped electrons in the outer zone (Lorentzen et al., 2001). Microburst precipitation was first observed from a balloon (Anderson and Milton, 1964), but these early measurements were only sensitive to $<$100 keV. The first balloon-based observations of microbursts sensitive to MeV energies were obtained during the MAXIS 2000 long duration balloon campaign. MAXIS was launched from McMurdo Station in Antarctica carrying a germanium spectrometer, a BGO scintillator and two X-ray imagers designed to measure the bremsstrahlung produced by precipitating electrons. The balloon circumnavigated the south pole in 18 days covering magnetic latitudes ranging from 58$^{\circ}-90$$^{\circ}$ South. During the week following a moderate geomagnetic storm (with Dst reaching -91 nT), MAXIS detected a total of over 16 hours of microburst precipitation. We present high resolution spectra obtained with the MAXIS germanium spectrometer which allow us to determine the precipitating electron energy distribution. The precipitating distribution will then be compared to the trapped distribution measured by the GPS and LANL satellites. We also examine the spatial distribution of the precipitation.
DE: 2716 Energetic particles, precipitating
DE: 2730 Magnetosphere--inner
DE: 2788 Storms and substorms
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting