HR: 1340h
AN: SM23A-1181    [Abstracts]
TI: Substorm Timing and Location Using The Combined CARISMA and THEMIS GMAG Magnetometers
AU: * Rae, I J
EM: jrae@phys.ualberta.ca
AF: University of Alberta, 11322 - 89 Avenue University of Alberta, Edmonton, T6G 2G7, Canada
AU: Milling, D K
EM: dmilling@phys.ualberta.ca
AF: University of Alberta, 11322 - 89 Avenue University of Alberta, Edmonton, T6G 2G7, Canada
AU: Mann, I R
EM: imann@phys.ualberta.ca
AF: University of Alberta, 11322 - 89 Avenue University of Alberta, Edmonton, T6G 2G7, Canada
AU: Murphy, k r
EM: kmurphy@phys.ualberta.ca
AF: University of Alberta, 11322 - 89 Avenue University of Alberta, Edmonton, T6G 2G7, Canada
AU: glassmeier, K
EM: kh.glassmeier@tu-braunschweig.de
AF: TU Braunschweig, TU Braunschweig Pockelsstr. 14, Braunschweig, D-38106, Germany
AU: Auster, U
EM: uli.auster@tu-braunschweig.de
AF: TU Braunschweig, TU Braunschweig Pockelsstr. 14, Braunschweig, D-38106, Germany
AU: Angelopoulos, V
EM: vassilis@ucla.edu
AF: Institute of Geophysics and Planetary Physics, Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 90095-1567, United States
AU: Russell, C T
EM: ctrussel@igpp.ucla.edu
AF: Institute of Geophysics and Planetary Physics, Institute of Geophysics and Planetary Physics, University of California, Los Angeles, CA 90095-1567, United States
AB: With the successful launch of the THEMIS spacecraft, the expansion of the CARISMA magnetometer array, and the deployment of the THEMIS GBOs, there now exists an exceptional opportunity to study fundamental ULF wave science in the nightside magnetosphere around substorm onset. Traditionally, substorm onset is usually determined by location and timing of ULF waves in the Pi2 (40-200 second period) range. With the current configuration of ground magnetometers, it is now possible to resolve frequencies in the Pi1 (1-40 second period) band using novel techniques such as Wavelet Analysis. With this technique, the entire spectrum of ULF waves associated with substorm onset can be accurately timed to approximately half of the wave period. We use a substorm location modeling algorithm [Cramoysan et al., 1995] to produce initial estimates of the locations of the upward and downward field aligned currents and the westward electrojet. We present results from several isolated substorms and find that the onset location of the Pi1 waves starts at or close to the location of the downward field-aligned current region and propagate isotropically away from this location. We discuss the implications of this result in terms of potential generation mechanisms for Pi1 waves at substorm onset, and for the physical processes operating at the onset of the substorm expansion phase.
DE: 2704 Auroral phenomena (2407)
DE: 2744 Magnetotail
DE: 2752 MHD waves and instabilities (2149, 6050, 7836)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting