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Article Dans Une Revue Journal of Geophysical Research Space Physics Année : 2018

Multiscale Currents Observed by MMS in the Flow Braking Region

R. Nakamura
Ali Varsani
  • Fonction : Auteur
Kevin J. Genestreti
  • Fonction : Auteur
Olivier Le Contel
T. K. M. Nakamura
  • Fonction : Auteur
W. Baumjohann
Tsugunobu Nagai
  • Fonction : Auteur
A. V. Artemyev
  • Fonction : Auteur
Joachim Birn
  • Fonction : Auteur
Victor A. Sergeev
  • Fonction : Auteur
Sergey Apatenkov
  • Fonction : Auteur
Robert E. Ergun
  • Fonction : Auteur
Barbara J. Giles
  • Fonction : Auteur
Y. V. Khotyaintsev
  • Fonction : Auteur
Werner Magnes
  • Fonction : Auteur
Barry Mauk
Anatoli Petrukovich
  • Fonction : Auteur
J. E. Stawarz
  • Fonction : Auteur
Robert J. Strangeway
  • Fonction : Auteur
Brian Anderson
  • Fonction : Auteur
James L. Burch
  • Fonction : Auteur
Ken R. Bromund
  • Fonction : Auteur
Ian Cohen
  • Fonction : Auteur
David Fischer
  • Fonction : Auteur
Allison Jaynes
  • Fonction : Auteur
Laurence Kepko
  • Fonction : Auteur
Guan Le
  • Fonction : Auteur
Ferdinand Plaschke
  • Fonction : Auteur
Geoff Reeves
  • Fonction : Auteur
Howard J. Singer
  • Fonction : Auteur
J. A. Slavin
  • Fonction : Auteur
Roy B. Torbert
  • Fonction : Auteur
Drew L. Turner
  • Fonction : Auteur

Résumé

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.

Dates et versions

hal-01895679 , version 1 (15-10-2018)

Identifiants

Citer

R. Nakamura, Ali Varsani, Kevin J. Genestreti, Olivier Le Contel, T. K. M. Nakamura, et al.. Multiscale Currents Observed by MMS in the Flow Braking Region. Journal of Geophysical Research Space Physics, 2018, 123 (2), pp.1260-1278. ⟨10.1002/2017JA024686⟩. ⟨hal-01895679⟩
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