Nonlinear Processes in Geophysics (Jan 2002)

On the properties of turbulent boundary layer over polar cusps

  • S. Savin,
  • J. Büchner,
  • G. Consolini,
  • B. Nikutowski,
  • L. Zelenyi,
  • E. Amata,
  • H. U. Auster,
  • J. Blecki,
  • E. Dubinin,
  • K. H. Fornacon,
  • H. Kawano,
  • S. Klimov,
  • F. Marcucci,
  • Z. Nemecek,
  • A. Pedersen,
  • J. L. Rauch,
  • S. Romanov,
  • J. Safrankova,
  • J. A. Sauvaud,
  • A. Skalsky,
  • P. Song,
  • Yu. Yermolaev

Journal volume & issue
Vol. 9, no. 5/6
pp. 443 – 451


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We study properties of nonlinear magnetic fluctuations in the turbulent boundary layer (TBL) over polar cusps during a typical TBL crossing on 19 June 1998. Interball-1data in the summer TBL are compared with that of Geotail in solar wind (SW) and Polar in the northern TBL. In the TBL two characteristic slopes are seen: ~ - 1 at (0.004- 0.08) Hz and ~ - 2.2 at (0.08-2) Hz. We present evidences that random current sheets with features of coherent solitons can result in: (i) slopes of ~ - 1 in the magnetic power spectra; (ii) demagnetization of the SW plasma in "diamagnetic bubbles"; (iii) nonlinear, presumably, 3-wave phase coupling with cascade features; (iiii) departure from the Gaussian statistics. We discuss the above TBL properties in terms of intermittency and self-organization of nonlinear systems, and compare them with kinetic simulations of reconnected current sheet at the nonlinear state. Virtual satellite data in the model current sheet reproduce valuable cascade-like spectral and bi-spectral properties of the TBL turbulence.