Magnetic Reconnection in Plasmas

Global and local properties of dayside magnetopause reconnection: Simulations and initial MMS results

Not scheduled

25m

132:028 (Nordita, Stockholm)

Invited Workshop, August 10-14

Speaker

John Dorelli (NASA-GSFC)

Description

Recent high resolution global magnetohydrodynamics (MHD) simulations of Earth's magnetosphere [Komar et al., 2013, Glocer et al., 2015] suggest that dayside magnetopause reconnection occurs at topological separators that extend across the entire dayside -- stretching from one polar cusp to the other -- for both northward and southward Interplanetary Magnetic Field (IMF) conditions. The recent simulations, performed using the BATS-R-US code, confirm previous results for generic northward IMF conditions obtained using the OpenGGCM code [Dorelli et al., 2007]: The simulated magnetosphere has a global magnetic topology consistent with that of a vacuum superposition (in which a uniform IMF is superposed on a dipole), predicting that component subsolar reconnection is topologically possible for essentially all IMF clock angles (excluding the singular pure northward case). Recent PIC simulations using the massively parallel VPIC code [Daughton et al., 2014], however, suggest that secondary island formation at the magnetopause produces turbulence and field line chaos, making the identification of topological X lines difficult or impossible (indeed, Daughton et al. [2014] suggest that the concept of "X line" loses its relevance in such turbulent reconnection scenarios). In this work, we present new high resolution BATS-R-US (both resistive and Hall MHD) and VPIC simulations demonstrating that topological separators exist in non-toroidal topologies (like the dayside magnetopause) even in the presence of secondary magnetic islands and associated turbulence. We use a high fidelity model of the Fast Plasma Investigation (FPI) on the Magnetospheric Multiscale (MMS) mission to predict local plasma signatures that can be used to identify topological separators, and we compare our simulations with initial observations from the FPI and FIELDS suites on MMS.