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Author Engebretson, M. J. ♦ Alford, J. L. ♦ Hughes, W. J.
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword PHYSICS ♦ LONG WAVE RADIATION ♦ ENERGY SPECTRA ♦ POLAR CUSP ♦ POLAR REGIONS ♦ CANADA ♦ ALASKA ♦ PLASMA WAVES ♦ GROUND LEVEL ♦ MILLI HZ RANGE
Abstract The authors have used magnetometer data from 10 locations in Arctic Canada and Greenland, covering over 5 hours in magnetic local time at magnetic latitudes from 75{degrees} to 79{degrees}, to characterize the dayside patterns of enhanced long-period ULF (10- to 600-s period) wave power at cusp/cleft latitudes. They conclude the following: (1) In agreement with earlier single-station studies, the authors find that the most common wave type is broadband noise (Pi 1-2). Distinct Pc 3-4 activity and more sustained monochromatic Pc 5 activity are most apparent when this broadband noise is weak. (2) Multistation observations also make clear that strong, broadband Pi 1-2 signals at these latitudes appears to be controlled largely by solar wind velocity. The authors found good correlations between the occurrence of strong Pi 1-2 signals and high solar wind velocity, and they also noted some dependence on the cone angle of the interplanetary magnetic field for moderate to low solar wind velocities. The authors speculate that there may be an additional dependence on enhanced levels of trapped plasma in regions topologically connected to the very high latitude dayside ionosphere, such as the entry layer, high-latitude dayside field minimum regions, or plasma mantle. Available satellite data on the level of trapped energetic electron fluxes at geosynchronous orbit showed that broadband power levels appeared to correlate with enhanced flux levels on the time scale of days, but not on shorter time scales, suggesting that any such dependence is not directly related to substorm injections. 31 refs., 9 figs., 2 tabs.
ISSN 01480227
Educational Use Research
Learning Resource Type Article
Publisher Date 1995-10-01
Publisher Place United States
Journal Journal of Geophysical Research
Volume Number 100
Issue Number A10


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