On the properties of turbulent boundary layer over polar cusps

S. Savin (1) , J. Büchner (2) , G. Consolini (3) , B. Nikutowski (2) , L. Zelenyi (1) , E. Amata (3) , H. U. Auster (4) , J. Blecki (5) , E. Dubinin (2) , K. H. Fornacon (4) , H. Kawano (6) , S. Klimov (1) , F. Marcucci (3) , Z. Nemecek (7) , A. Pedersen (8) , Jean-Louis Rauch (9) , S. Romanov (1) , J. Safrankova (7) , J. A. Sauvaud (10) , A. Skalsky (1) , P. Song (11) , Yu. Yermolaev (1)

1 IKI - Space Research Institute of the Russian Academy of Sciences
2 MPI Aeronomie - Max-Planck-Institut für Aeronomie
3 Interplanetary Space Phys. Inst.
4 TU - Technical University of Berlin / Technische Universität Berlin
5 CBK - Space Research Centre of Polish Academy of Sciences
6 Kyushu University
7 UK - Univerzita Karlova [Praha, Česká republika] = Charles University [Prague, Czech Republic]
8 UiO - University of Oslo
9 LPCE - Laboratoire de physique et chimie de l'environnement
10 CESR - Centre d'étude spatiale des rayonnements
11 UMass Amherst - University of Massachusetts [Amherst]

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.

Domaines: Cosmologie et astrophysique extra-galactique [astro-ph.CO]; Astrophysique [astro-ph]; Sciences de la Terre

S. Savin, J. Büchner, G. Consolini, B. Nikutowski, L. Zelenyi, et al.. On the properties of turbulent boundary layer over polar cusps. Nonlinear Processes in Geophysics, 2002, 9 (5/6), pp.443-451. ⟨hal-00331062⟩