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Electromagnetic Ion Cyclotron Waves in the High-Altitude Cusp: Polar ObservationsHigh-resolution magnetic field data from the Polar Magnetic Field Experiment (MFE) show that narrow-band waves at frequencies approx. 0.2-3 Hz are a permanent feature in the vicinity of the polar cusp. The waves have been found in the magnetosphere adjacent to the cusp (both poleward and equatorward of the cusp) and in the cusp itself. The occurrence of waves is coincident with depression of magnetic field strength associated with enhanced plasma density, indicating the entry of magnetosheath plasma into the cusp region. The wave frequencies are generally scaled by the local proton cyclotron frequency and vary between 0.2 and 1.7 times local proton cyclotron frequency. This suggests that the waves are generated in the cusp region by the precipitating magnetosheath plasma. The properties of the waves are highly variable. The waves exhibit both left-handed and right-handed polarization in the spacecraft frame. The propagation angles vary from nearly parallel to nearly perpendicular to the magnetic field. We find no correlation among wave frequency, propagation angle, and polarization. Combined magnetic field and electric field data for the waves indicate that the energy flux of the waves is guided by the background magnetic field and points downward toward the ionosphere.
Document ID
20050180485
Document Type
Conference Paper
Authors
Le, G. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Blanco-Cano, X. (Ciudad Univ. Mexico City, Mexico)
Russell, C. T. (California Univ. Los Angeles, CA, United States)
Zhou, X.-W. (California Univ. Berkeley, CA, United States)
Mozer, F. (California Univ. Berkeley, CA, United States)
Trattner, K. J. (Lockheed Martin Palo Alto Research Lab. Palo Alto, CA, United States)
Fuselier, S. A. (Lockheed Martin Palo Alto Research Lab. Palo Alto, CA, United States)
Anderson, B. J. (Johns Hopkins Univ. Laurel, MD, United States)
Date Acquired
August 23, 2013
Publication Date
January 1, 2005
Subject Category
Geophysics
Meeting Information
2005 Chapman Conference on Magnetospheric ULF Waves(San Diego, CA)
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.