THE LOW-LATITUDE BOUNDARY-LAYER AT THE FLANKS OF THE MAGNETOPAUSE

This is a brief overview on what we know and do not know about the low -latitude boundary layer (LLBL) at the flanks of the magnetotail. On t he basis of recent observations, simulations and theories we conclude that reconnection is the dominant process in generating the LLBL and i ts structure probably even under northward IMF conditions. Part of the LLBL always seems to be on open field lines. Possibly the LLBL posses ses a double structure with its outer part open and inner part closed. Anomalous diffusive processes cannot sustain the LLBL but provide suf ficient diffusivity for reconnection. Strong diffusion is only expecte d in narrow localized regions and can make the transition to superdiff usion. Kelvin-Helmholtz instability (KHI) is favoured for northward IM F, producing vortices at the tail hanks. Its contribution to efficient mass transport still remains questionable. Coupling of the LLBL to th e ionosphere can strongly affect the internal structure of the LLBL, c ausing turbulent eddies and detachments of plasma blobs as also field- aligned currents and electron heating. The structure and dynamics of t he LLBL are affected by field-aligned electric potentials that decoupl e the LLBL from the ionosphere. Non-ideal coupling simulations suggest that the dusk flank is decoupled, favouring KHI, while the dawn flank is dominated by currents and turbulence.