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Abstract
We report on the large-scale evolution of dipolarization in the near-Earth plasma sheet during an intense (AL ~ −1000 nT) substorm on August 10, 2016, when multiple spacecraft at radial distances between 4 and 15 R E were present in the night-side magnetosphere. This global dipolarization consisted of multiple short-timescale (a couple of minutes) B z disturbances detected by spacecraft distributed over 9 MLT, consistent with the large-scale substorm current wedge observed by ground-based magnetometers. The four spacecraft of the Magnetospheric Multiscale were located in the southern hemisphere plasma sheet and observed fast flow disturbances associated with this dipolarization. The high-time-resolution measurements from MMS enable us to detect the rapid motion of the field structures and flow disturbances separately. A distinct pattern of the flow and field disturbance near the plasma boundaries was found. We suggest that a vortex motion created around the localized flows resulted in another field-aligned current system at the off-equatorial side of the BBF-associated R1/R2 systems, as was predicted by the MHD simulation of a localized reconnection jet. The observations by GOES and Geotail, which were located in the opposite hemisphere and local time, support this view. We demonstrate that the processes of both Earthward flow braking and of accumulated magnetic flux evolving tailward also control the dynamics in the boundary region of the near-Earth plasma sheet.[Figure not available: see fulltext.]
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1 Space Research Institute, Austrian Academy of Sciences, Graz, Austria
2 Tokyo Institute of Technology, Tokyo, Japan
3 Space Science Institute, Boulder, CO, USA
4 St. Petersburg State University, St. Petersburg, Russia
5 Laboratoire de Physique des Plasmas, CNRS/Ecole polytechnique/UPMC Univ Paris 06/Univ. Paris-Sud/Observatoire de Paris, Paris, France
6 University of California, Los Angeles, CA, USA
7 LASP, University of Colorado, Boulder, CO, USA
8 Southwest Research Institute, San Antonio, TX, USA
9 NASA, GSFC, Greenbelt, MD, USA
10 Swedish Institute of Space Physics, Uppsala, Sweden
11 Royal Institute of Technology, Stockholm, Sweden
12 Applied Physics Laboratory, Johns Hopkins University, Laurel, MD, USA
13 NOAA Space Weather Prediction Center, Boulder, CO, USA
14 Department of Physics, Imperial College London, London, UK
15 Department of Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI, USA
16 Space Sciences Department, Aerospace Corporation, Los Angeles, CA, USA