Multi-spacecraft tracing of turbulent boundary layer Original Research Article

Multi-spacecraft tracing of the high latitude magnetopause (MP) and boundary layers and Interball-1 statistics indicate that: 1. (a) The turbulent boundary layer (TBL) is a persistent feature in the region of the cusp and ‘sash’, a noticeable part of the disturbances weakly depends on the interplanetary magnetic field By component; TBL is a major site for magnetosheath (MSH) plasma penetration inside the magnetosphere through percolation and local reconnection. 2. (b) The TBL disturbances are mainly inherent with the characteristic kinked double-slope spectra and, most probably, 3-wave cascading. The bi-spectral phase coupling indicates self-organization of the TBL as the entire region with features of the non-equilibrium multi-scale and multi-phase system in the near-critical state. 3. (c) Weʹve found the different outer cusp topologies in summer/winter periods: the summer cusp throat is open for the decelerated MSH flows, the winter one is closed by the distant MP with a large-scale (∼several Re) diamagnetic ‘plasma ball’ inside the MP; the ‘ball’ is filled from MSH through patchy merging rather than large-scale reconnection. 4. (d) A mechanism for the energy release and mass inflow is the local TBL reconnection, which operates at the larger scales for the average anti-parallel fields and at the smaller scales for the nonlinear fluctuating fields; the latter is operative throughout the TBL. The remote from TBL anti-parallel reconnection seems to happen independently.