Nonlinear Processes in Geophysics www.nonlin-processes-geophys.net 1023-5809 1607-7946 9 5/6 2002 10.5194/npg-9-443-2002 http://www.nonlin-processes-geophys.net/9/443/2002/ http://www.nonlin-processes-geophys.net/9/443/2002/npg-9-443-2002.html http://www.nonlin-processes-geophys.net/9/443/2002/npg-9-443-2002.pdf 443 451 0000-00-00 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 Space Research Institute, Russian Academy of Sciences, Profsoyuznaya 84/32, Moscow, 117810, Russia Interplanetary Space Phys. Inst., CNR, Roma, Italy Max-Planck-Institut für Aeronomie, Katlenburg-Lindau, Germany Space Res. Center, Polish Academy Sci., Warsaw, Poland Laboratory Phys. and Chemistry Environment, Orleans, France University of Massachusetts at Lowell, Lowell, MA, USA CESR, Toulouse, France Charles University, Prague, Czech Republic University of Oslo, Norway Kyushu University, Japan Technical University, Braunschweig, Germany 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.