Annales Geophysicae (Jun 2012)

Spatial distribution of rolled up Kelvin-Helmholtz vortices at Earth's dayside and flank magnetopause

  • M. G. G. T. Taylor,
  • H. Hasegawa,
  • B. Lavraud,
  • T. Phan,
  • C. P. Escoubet,
  • M. W. Dunlop,
  • Y. V. Bogdanova,
  • A. L. Borg,
  • M. Volwerk,
  • J. Berchem,
  • O. D. Constantinescu,
  • J. P. Eastwood,
  • A. Masson,
  • H. Laakso,
  • J. Soucek,
  • J. Soucek,
  • A. N. Fazakerley,
  • H. U. Frey,
  • E. V. Panov,
  • C. Shen,
  • J. K. Shi,
  • D. G. Sibeck,
  • Z. Y. Pu,
  • J. Wang,
  • J. A. Wild

DOI
https://doi.org/10.5194/angeo-30-1025-2012
Journal volume & issue
Vol. 30
pp. 1025 – 1035

Abstract

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The Kelvin-Helmholtz Instability (KHI) can drive waves at the magnetopause. These waves can grow to form rolled-up vortices and facilitate transfer of plasma into the magnetosphere. To investigate the persistence and frequency of such waves at the magnetopause we have carried out a survey of all Double Star 1 magnetopause crossings, using a combination of ion and magnetic field measurements. Using criteria originally used in a Geotail study made by Hasegawa et al. (2006) (forthwith referred to as H2006), 17 candidate events were identified from the entire TC-1 mission (covering ~623 orbits where the magnetopause was sampled), a majority of which were on the dayside of the terminator. The relationship between density and shear velocity was then investigated, to identify the predicted signature of a rolled up vortex from H2006 and all 17 events exhibited some level of rolled up behavior. The location of the events had a clear dawn-dusk asymmetry, with 12 (71%) on the post noon, dusk flank suggesting preferential growth in this region.