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Initial POLAR MFE Observation of Substorm Signatures in the Polar Magnetosphere

H. Kawano1, G. Le1, C. T. Russell1, G. Rostoker2, T. Mukai3, H. Spence4, ...

1Institute of Geophysics and Planetary Physics, University of California, Los Angeles, Los Angeles, CA 90095-1567

2Department of Physics, University of Alberta, Edmonton, Alberta, T6G 2J1, Canada

3Institute of Space and Astronautical Science, Sagamihara, Kanagawa 229, Japan

4Department of Astronomy and Center for Space Physics, Boston University, 725 Commonwealth Ave., Boson, MA 02215


This paper studies substorm influences in the polar magnetosphere using data from the POLAR magnetic field experiment (MFE). The POLAR spacecraft remains in the high altitude polar magnetosphere for extended periods around apogee. There it can stay at nearly constant altitude through all phases of a substorm, which was not possible on previous missions. We report such an event on March 28, 1996. Ground magnetometers monitored substorm activity, while the POLAR spacecraft, directly over the pole at (-0.8,-0.6,8.5) in GSM coordinates, observed a corresponding perturbation in the total magnetic field strength. The total magnetic field first increased, then recovered toward quiet levels, consistent with erosion of magnetic flux from the dayside magnetosphere, followed by transport of that flux to the magnetotail, and eventual onset of tail reconnection and the return of that magnetic flux to the dayside magnetosphere.

Kawano Hideaki
Sat Jan 4 18:21:35 JST 1997