Dynamic Magnetosphere-Ionosphere Coupling via Forward and Inverse Karman Vortexes

Abstract:

Global magnetospheric coherent structures related to the dynamical coupling between the dayside magnetopause frontier and ionosphere for a northward IMF configuration, are analyzed using global 3D MHD simulations. The main goal is to reach a global synthetic scenario focusing on the formation of 3D unstable/stable structures developed among inside/outside magnetopause and ionosphere in different steps from the dayside to the night side. They are: (i) the transverse Kelvin-Helmholtz (K-H) vortexes are generated along and outside the magnetopause near the dayside region, while other K-H vortexes are generated along and inside the magnetopause; (ii) these vortexes are unstable in one each row, adjust, and evolve into a marginal stable Karman vortex street near the equator; (iii) the inside K-H vortexes extends toward northward/southward ionospheres to form inverse Karman vortex street in north/south ionospheres; (ii) all rows of vortexes are shed off soon from the magnetopause/ionosphere, respectively; (iv) these forward/inverse Karman vortexes soon are reformed into stable longitudinal (stream-wise) coherent vortexes and survive for long time over large distances x~-130 to 140Re in the magnetotail. Generation mechanisms of both the inverse Karman vortexes and the longitudinal vortexes, possibly vortex stretching via hairpin vortexes etc., are still under intensive investigations. All these processes lead to the global and consistent MI coupling and formation of magnetospheric coherent structures.