On the impact of fluctuations on the magnetotail reconnection

Abstract:

When the cross-tail current sheet is sufficiently thin, any adequate perturbation can trigger a reconnection. In this presentation we discuss initial results of a statistical correlation study using 8+ years of THEMIS measurements between magnetosheath and plasma sheet fluctuations (magnetic and velocity fields, and mass flux) and in the ULF Pc2-Pc5 ranges for Southward, Northward, and Parker-Spiral IMF, and for fast and slow solar wind intervals. The statistical fluctuation properties are compared to the typical magnetotail reconnection characteristics such as reconnection flows, and electron to ion temperature and velocity ratios. Global LFM MHD simulations are used for studying how deeply into the plasma sheet the vorticity created by the magnetopause processes such as Kelvin-Helmholtz Instability can penetrate and what are the corresponding amplitudes. Local MHD simulations in a Modified Harris-sheet equilibrium are used for studying how the fluctuations in magnetic field and mass flux (with the observed amplitudes and frequencies from the THEMIS statistical study) impact the magnetotail reconnection characteristics.