Multiscale Currents Observed by MMS in the Flow Braking Region

Rumi Nakamura; Ali Varsani; Kevin J Genestreti; Olivier Le Contel; Takuma Nakamura; Wolfgang Baumjohann; Tsugunobu Nagai; Anton Artemyev; Joachim Birn; Victor A Sergeev; Sergey Apatenkov; Robert E Ergun; Stephen A Fuselier; Daniel J Gershman; Barbara J Giles; Yuri V Khotyaintsev; Per‐Arne Lindqvist; Werner Magnes; Barry Mauk; Anatoli Petrukovich; Christopher T Russell; Julia Stawarz; Robert J Strangeway; Brian Anderson; James L Burch; Ken R Bromund; Ian Cohen; David Fischer; Allison Jaynes; Laurence Kepko; Guan Le; Ferdinand Plaschke; Geoff Reeves; Howard J Singer; James A Slavin; Roy B Torbert; Drew L Turner

doi:10.1002/2017JA024686

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Multiscale Currents Observed by MMS in the Flow Braking Region

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Multiscale Currents Observed by MMS in the Flow Braking Region

Rumi Nakamura, Ali Varsani, Kevin J Genestreti, Olivier Le Contel, Takuma Nakamura, Wolfgang Baumjohann, Tsugunobu Nagai, Anton Artemyev, Joachim Birn, Victor A Sergeev, …

Journal of geophysical research. Space physics, Vol.123(2), pp.1260-1278

02/2018

DOI: 10.1002/2017JA024686

PMCID: PMC5993344

PMID: 29938154

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Abstract

We present characteristics of current layers in the off‐equatorial near‐Earth plasma sheet boundary observed with high time‐resolution measurements from the Magnetospheric Multiscale mission during an intense substorm associated with multiple dipolarizations. The four Magnetospheric Multiscale spacecraft, separated by distances of about 50 km, were located in the southern hemisphere in the dusk portion of a substorm current wedge. They observed fast flow disturbances (up to about 500 km/s), most intense in the dawn‐dusk direction. Field‐aligned currents were observed initially within the expanding plasma sheet, where the flow and field disturbances showed the distinct pattern expected in the braking region of localized flows. Subsequently, intense thin field‐aligned current layers were detected at the inner boundary of equatorward moving flux tubes together with Earthward streaming hot ions. Intense Hall current layers were found adjacent to the field‐aligned currents. In particular, we found a Hall current structure in the vicinity of the Earthward streaming ion jet that consisted of mixed ion components, that is, hot unmagnetized ions, cold E × B drifting ions, and magnetized electrons. Our observations show that both the near‐Earth plasma jet diversion and the thin Hall current layers formed around the reconnection jet boundary are the sites where diversion of the perpendicular currents take place that contribute to the observed field‐aligned current pattern as predicted by simulations of reconnection jets. Hence, multiscale structure of flow braking is preserved in the field‐aligned currents in the off‐equatorial plasma sheet and is also translated to ionosphere to become a part of the substorm field‐aligned current system. Key Points Multiscale field‐aligned currents in the boundary of the expanding plasma sheet during plasma jet braking intervals are resolved Intense Hall current layers are found at the inner boundary of the hot Earthward streaming ion jets and flow shear regions Both plasma jet diversion and Hall effects from reconnection region contribute to the structure of the substorm wedge currents

field‐aligned current

flow braking

magnetic reconnection

Magnetospheric Multiscale (MMS)

plasma sheet boundary

Details

Title: Subtitle: Multiscale Currents Observed by MMS in the Flow Braking Region
Creators: Rumi Nakamura - Austrian Academy of Sciences
Ali Varsani - Austrian Academy of Sciences
Kevin J Genestreti - Austrian Academy of Sciences
Olivier Le Contel - École Polytechnique
Takuma Nakamura - Austrian Academy of Sciences
Wolfgang Baumjohann - Austrian Academy of Sciences
Tsugunobu Nagai - Tokyo Institute of Technology
Anton Artemyev - University of California, Los Angeles
Joachim Birn - Space Science Institute
Victor A Sergeev - St Petersburg University
Sergey Apatenkov - St Petersburg University
Robert E Ergun - University of Colorado Boulder
Stephen A Fuselier - Southwest Research Institute
Daniel J Gershman - Goddard Space Flight Center
Barbara J Giles - Goddard Space Flight Center
Yuri V Khotyaintsev - Swedish Institute of Space Physics
Per‐Arne Lindqvist - KTH Royal Institute of Technology
Werner Magnes - Austrian Academy of Sciences
Barry Mauk - Johns Hopkins University
Anatoli Petrukovich - Space Research Institute (IKI) RAS Moscow Russia.
Christopher T Russell - University of California, Los Angeles
Julia Stawarz - Imperial College London
Robert J Strangeway - University of California, Los Angeles
Brian Anderson - Johns Hopkins University
James L Burch - Southwest Research Institute
Ken R Bromund - Goddard Space Flight Center
Ian Cohen - Johns Hopkins University
David Fischer - Austrian Academy of Sciences
Allison Jaynes - University of Colorado Boulder
Laurence Kepko - Goddard Space Flight Center
Guan Le - Goddard Space Flight Center
Ferdinand Plaschke - Austrian Academy of Sciences
Geoff Reeves - Los Alamos National Laboratory
Howard J Singer - National Oceanic and Atmospheric Administration
James A Slavin - University of Michigan
Roy B Torbert - University of New Hampshire
Drew L Turner - The Aerospace Corporation
Resource Type: Journal article
Publication Details: Journal of geophysical research. Space physics, Vol.123(2), pp.1260-1278
DOI: 10.1002/2017JA024686
PMID: 29938154
PMCID: PMC5993344
NLM abbreviation: J Geophys Res Space Phys
ISSN: 2169-9380
eISSN: 2169-9402
Number of pages: 19
Grant note: NASA (NNX13AD21G; NNX13AD10G) Austrian Science Fund (FWF) (I2016‐N20; I3506‐N27) NSF (160265; 1203711) RSF (18‐47‐05001)
Language: English
Date published: 02/2018
Academic Unit: Physics and Astronomy; University College Courses
Record Identifier: 9984199940602771

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