HR: 09:20h
AN: SM21C-06    [Abstracts]
TI: Midlatitude Pi2 Timing of a Multiple Onset Substorm Observed by THEMIS on March 23, 2007
AU: * McPherron, R L
EM: rmcpherron@igpp.ucla.edu
AF: Institute of Geophysics and Planetary Physics, Univ. of Calif Los Angeles, Los Angeles, CA 90095, United States
AU: Angelopolous, V
EM: vassilis@ssl.berkeley.edu
AF: Institute of Geophysics and Planetary Physics, Univ. of Calif Los Angeles, Los Angeles, CA 90095, United States
AU: Zhou, S
EM: sha@atmos.ucla.edu
AF: Dept. Ocean & Atmos. Sci., Univ. of Calif Los Angeles, Los Angeles, CA 90095, United States
AU: Yumoto, K
EM: yumoto@geo.kyushu-u.ac.jp
AF: Space Env Res Ctr, Kyushu Univ Graduate School of Sciences Space Env Res Ctr, Kyushu Univ Graduate School of Sciences, 6-10-1 Hakozaki Higashiku, Fukuoka, 812-8581, Japan
AU: Shiokawa, K
EM: shiokawa@stelab.nagoya-u.ac.jp
AF: Solar-Terrestrial Environment Lab, Nagoya University, 3-13, Honohara, Toyokawa, Aichi, Toyokawa, 442-8507, Japan
AU: Singer, H
EM: howard.singer@noaa.gov
AF: Space Enviornment Center, NOAA Broadway, Boulder, CO 80303, United States
AU: Rae, J
EM: jrae@phys.ualberta.ca
AF: Dept. of Physics, Univ. of Alberta, Edmonton, Alb T6G2G7, Canada
AB: It is generally accepted that Pi 2 pulsations are associated with the onset of a magnetospheric substorm expansion phase. However, many substorms include more than one Pi 2 burst and it is sometimes difficult to determine which burst corresponds to the expansion onset rather than a pseudo breakup or poleward boundary intensification so that additional information is needed to make a positive identification of onset. In addition there are other concerns including the strength of the Pi 2 relative to background noise, different types of Pi 2, the polarization of the Pi 2 signal, and time delays that are functions of location relative to the onset meridian. In this paper we utilize data from several arrays of ULF wave detectors including the Themis ground stations in North America and the Circum Pacific Array to determine how these factors effect the accuracy of the onset determination. Additional information is provided by the Intermagnet ground magnetometers, Themis all sky cameras and GOES and LANL spacecraft at synchronous orbit. The time-line provided by the Pi2 analysis provides a framework with which the observations at the Themis spacecraft can be interpreted.
DE: 2704 Auroral phenomena (2407)
DE: 2744 Magnetotail
DE: 2788 Magnetic storms and substorms (7954)
DE: 2790 Substorms
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting