An Examination of the Magnetic Merging Process at the Dayside Magnetopause

Petrinec, S. M., S. A. Fuselier, and J. Berchem

The roles of component and anti-parallel reconnection at the dayside
magnetopause are examined in this study, using ionospheric cusp emission
observations from the Spectrographic Imager (SI) part of the Far
Ultraviolet (FUV) instrument on board the Imager for Magnetopause-to-Aurora
Global Exploration (IMAGE) spacecraft, along with a semi-empirical magnetic
field model, and results from a magnetohydrodynamic model. An event is
examined for which observations of strong proton emissions were identified.
Strictly anti-parallel merging at the dayside magnetopause is found to be
insufficient to explain the cusp proton observations. A significant amount
of component merging (as much as 40 degrees from anti-parallel) is needed
for the ionospheric footpoints of dayside merging region to favorably match
the observations of the cusp. This case study lends strong support to the
importance of component magnetic field merging to the transport of flux and
energy from the solar wind into the magnetosphere.

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To be presented at the Magnetospheric Imaging Workshop, 
Yosemite National Park, California, U.S.A., Feb. 5-8, 2002.