SM43A-06
Mapping Out the Diffusion Region in Magnetopause Reconnection: from CLUSTER to Magnetospheric Multiscale

Thursday, 17 December 2015: 14:46
2018 (Moscone West)
Li-Jen Chen1, Michael Hesse1, Shan Wang2, Craig J Pollock3, Roy B Torbert2, Daniel J Gershman4, John Dorelli1, Barbara L Giles1, Naoki Bessho5, William S Daughton6, James L Burch7 and The MMS Team, (1)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (2)University of New Hampshire Main Campus, Durham, NH, United States, (3)NASA Goddard Space Flight Center, Heliophysics Sci. Div., Greenbelt, MD, United States, (4)University of Michigan Ann Arbor, Department of Atmospheric, Oceanic and Space Sciences, Ann Arbor, MI, United States, (5)University of Maryland College Park, College Park, MD, United States, (6)Los Alamos National Laboratory, Plasma Theory and App, Los Alamos, NM, United States, (7)Southwest Research Institute, San Antonio, TX, United States
Abstract:
The ion and electron diffusion regions in magnetopause reconnection are mapped out with distinct
plasma distribution functions and field structures using data from the Magnetospheric Multiscale (MMS) and CLUSTER missions as well as
particle-in-cell (PIC) simulations. The four-point measurements from CLUSTER provide in part the reality check for
the simulation predictions concerning the ion diffusion region, including electron distribution maps for the inflow, separatrix, and exhaust, the plasma flow patterns, and the
electric and magnetic field structures. A number of candidate electron diffusion region (EDR) crossings
by CLUSTER have been identified based on combined field reversals, density gradients, and jet reversals. Surrounding the candidate EDR are regions of accelerated and heated
plasmas with anisotropic distribution functions that often consist of multiple components.
However, the highly structured electron distribution functions characteristic of the EDR predicted by PIC remain
elusive. The unprecedented high-cadence three-dimensional measurements
from the Fast Plasma Investigation and the FIELDS suite onboard the four MMS spacecraft
open up the possibilities to resolve the EDR. We will demonstrate how MMS measurements
push forward the frontier of our understanding on the diffusion region physics in magnetopause reconnection.
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