The evolution of mirror type magnetic fluctuations in the magnetosheath based on multipoint observations

M. Tátrallyay, G. Erdos, A. Balogh, I. Dandouras

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Two orbits were selected in January-February 2006 when the separation between the Cluster spacecraft was large and mirror type magnetic field fluctuations were observed by all spacecraft in different regions of the terrestrial magnetosheath. Minimum variance analysis was applied to find the mirror type fluctuations, and the amplitude of the fluctuations was determined individually. Mirror mode structures are moving along the streamlines frozen in the plasma. A model was developed for the calculation of plasma flowtime from the bow shock to the observation point. The growth rate of the field strength perturbations was estimated by comparing the amplitudes of fluctuations observed simultaneously at distant locations (∼10,000 km) based on the assumption that δB ∼ exp(γt). The obtained growth rate values were about an order of magnitude smaller than those provided by linear models and they decreased in the inner regions of the magnetosheath, indicating some saturation in the growth of the waves when proceeding towards the magnetopause. The results of these two case studies suggest that mirror type fluctuations originate from the compression region downstream of the quasi-perpendicular bow shock, and the growth of the fluctuations cannot be described by linear approximations.

Original languageEnglish
Pages (from-to)1537-1544
Number of pages8
JournalAdvances in Space Research
Issue number10
Publication statusPublished - 2008



  • Growth rate of waves
  • Mirror mode instability
  • Mirror type magnetic field fluctuations
  • Plasma streamlines
  • Quasi-perpendicular bow shock

ASJC Scopus subject areas

  • Aerospace Engineering
  • Astronomy and Astrophysics
  • Geophysics
  • Atmospheric Science
  • Space and Planetary Science
  • Earth and Planetary Sciences(all)

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