Correlation between Large-Amplitude Electric Field Signatures Observed by Polar
and Cluster within the Terrestrial Plasma Sheet and Ground-Based Signatures of
Substorm Onset

J.W. Bonnell, F.S. Mozer, V. Angelopoulos, H.U. Frey, and S. Mende


The precession of the Polar spacecraft orbit puts apogee (~9 Re) near the
equator during 2000-2003 and allows correlative studies of electric fields and
plasmas between Polar and the satellites of the Cluster constellation (apogee
~19 Re). This allows one to preview the sorts of radial and azimuthal alignments
planned for the inner satellites of the THEMIS mission, and to better understand
the relationships between the in-situ plasma and field measurements and the
ground-based signatures of substorm onset.  We have identified several dozen
events spanning this interval where large-amplitude > 50 mV/m), temporally
isolated, impulsive electric field fluctuations are identified on both Polar and
Cluster. We compare the relative geomagnetic positions, timing, and amplitudes
of each event as well as the relationship between those parameters and the
ground-based (AE and magnetometer chain data) and orbital imaging signatures
(IMAGE and Polar) of substorm onset.

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Presentation, Fall A.G.U. Meeting, San Francisco, CA, 13-17 December 2004