Pc3 Pulsations in the Cusp

  1. M. J. Engebretson,
  2. K. Takahashi and
  3. M. Scholer
  1. John V. Olson1 and
  2. Brian J. Fraser2

Published Online: 3 APR 2013

DOI: 10.1029/GM081p0325

Solar Wind Sources of Magnetospheric Ultra-Low-Frequency Waves

Solar Wind Sources of Magnetospheric Ultra-Low-Frequency Waves

How to Cite

Olson, J. V. and Fraser, B. J. (1994) Pc3 Pulsations in the Cusp, in Solar Wind Sources of Magnetospheric Ultra-Low-Frequency Waves (eds M. J. Engebretson, K. Takahashi and M. Scholer), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM081p0325

Author Information

  1. 1

    Geophysical Institute, University of Alaska, Fairbanks, AK

  2. 2

    Physics Department, University of Newcastle, Newcastle 2308, Nsw, Australia

Publication History

  1. Published Online: 3 APR 2013
  2. Published Print: 1 JAN 1994

ISBN Information

Print ISBN: 9780875900407

Online ISBN: 9781118663943



  • Magnetosphere;
  • Radio waves;
  • Solar wind


The presence of enhanced Pc3 pulsation activity is one of the salient features of the dayside cusp/boundary layer system as observed by ground-based magnetometers. Using the results of earlier studies which correlated optical and magnetic signatures of the cusp and nearby boundary layers, we are able to differentiate the Pc3 signals present in those two structures. We have studied the Pc3 spectrum beneath the boundary layers and the cusp using data from pairs of stations in order to infer the local coherence of the pulsations. The first pair of stations used were Cape Parry and Sachs Harbor in Canada which are separated by approximately 150 km. The second pair are the near conjugate stations of Longyearbyen, Svalbard and Davis, Antarctica. Pc3 detected in the boundary layers are characterized by large amplitude and broad-band features and show little or no inter-station coherence. The Pc3 detected in the central cusp tend to be narrow-band packets which show good correlation, even between hemispheres. These observations are consistent with those of Engebretson [1986b, 1991a]. The lack of coherence between the two northern stations implies a short correlation length for the precipitating beams producing the Pc3 variations in the boundary layers. The correlation of central cusp Pc3 implies coherent illumination of the cusp region which leads to the conclusion that these pulsations have their source upstream of the magnetopause.