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Pc3 activity at low geomagnetic latitudes - A comparison with solar wind observationsOn an hourly time-scale the different roles of the solar wind and interplanetary magnetic field (IMF) parameters on ground micropulsation activity can be better investigated than at longer time-scales. A long-term comparison between ground measurements made at L'Aquila and IMP 8 observations confirms the solar wind speed as the key parameter for the onset of pulsations even at low latitudes, although additional control of the energy transfer from the interplanetary medium to the earth's magnetosphere is clearly exerted by the cone angle. Above about 20 mHz the frequency of pulsations is confirmed to be closely related to the IMF magnitude while, in agreement with model predictions, the IMF magnitude is related to the amplitude of the local fundamental resonant mode. We provide an interesting example in which high resolution measurements simultaneously obtained in the foreshock region and on the ground show that external transversal fluctuations do not penetrate deep into the low latitude magnetosphere.
Document ID
Document Type
Reprint (Version printed in journal)
Villante, U. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Lepidi, S. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Vellante, M. (L'Aquila Univ. Italy)
Lazarus, A. J. (MIT Cambridge, MA, United States)
Lepping, R. P. (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 15, 2013
Publication Date
October 1, 1992
Publication Information
Publication: Planetary and Space Science
Volume: 40
Issue: 10
ISSN: 0032-0633
Subject Category
Distribution Limits