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Cluster spacecraft observations of a ULF wave enhanced by Space Plasma Exploration by Active Radar (SPEAR)

Research output: Contribution to journalJournal article


  • S. V. Badman
  • D. M. Wright
  • L. B. N. Clausen
  • R. C. Fear
  • T. R. Robinson
  • T. K. Yeoman
Journal publication date2009
JournalAnnales Geophysicae
Number of pages9
Original languageEnglish


Space Plasma Exploration by Active Radar (SPEAR) is a high-latitude ionospheric heating facility capable of exciting ULF waves on local magnetic field lines. We examine an interval from 1 February 2006 when SPEAR was transmitting a 1 Hz modulation signal with a 10 min on-off cycle. Ground magnetometer data indicated that SPEAR modulated currents in the local ionosphere at 1 Hz, and enhanced a natural field line resonance with a 10 min period. During this interval the Cluster spacecraft passed over the heater site. Signatures of the SPEAR-enhanced field line resonance were present in the magnetic field data measured by the magnetometer on-board Cluster-2. These are the first joint ground- and space-based detections of field line tagging by SPEAR.

Bibliographic note

© Author(s) 2009. This work is distributed under the Creative Commons Attribution 3.0 License.