Effects in the Near-Magnetopause Magnetosheath Elicited by Large-Amplitude Alfvénic Fluctuations Terminating in a Field and Flow Discontinuity

Authors

Charlie J. Farrugia, University of New HampshireFollow
C. M. S. Cohen, California Institute of Technology
Bernard J. Vasquez, University of New HampshireFollow
Noe Lugaz, University of New HampshireFollow
L. Alm, Swedish Institute of Space Physics
Roy B. Torbert, University of New HampshireFollow
Matthew Argall, University of New HampshireFollow
K. Paulson, Harvard-Smithsonian Center for Astrophysics
Benoit Lavraud, Universite de Toulouse
D. J. Gershman, NASA Goddard Space Flight Center
F. T. Gratton, National Academy of Science of Buenos Aires
Hiroshi Matsui, University of New HampshireFollow
A. J. Rogers, University of New Hampshire
Terry G. Forbes, University of New HampshireFollow
D. Payne, University of New Hampshire
R. Ergun, University of Colorado
J. L. Burch, Southwest Research Institute
C. T. Russell, University of California
R. J. Strangeway, University of California
J. Shuster, NASA Goddard Space Flight Center
R. Nakamura, Space Research Institute
S. A. Fuselier, University of Texas
B. L. Giles, NASA Goddard Space Flight Center
Y. V. Khotyaintsev, Swedish Institute of Space Physics
P. A. Lindqvist, Swedish Institute of Space Physics
G. T. Marklund, Swedish Institute of Space Physics
S. M. Petrinec, Lockheed Martin Advanced Technology Center
C. J. Pollock, West Virginia University

Abstract

In this paper we report on a sequence of large-amplitude Alfvénic fluctuations terminating in a field and flow discontinuity and their effects on electromagnetic fields and plasmas in the near-magnetopause magnetosheath. An arc-polarized structure in the magnetic field was observed by the Time History of Events and Macroscale Interactions during Substorms-C in the solar wind, indicative of nonlinear Alfvén waves. It ends with a combined tangential discontinuity/vortex sheet, which is strongly inclined to the ecliptic plane and at which there is a sharp rise in the density and a drop in temperature. Several effects resulting from this structure were observed by the Magnetospheric Multiscale spacecraft in the magnetosheath close to the subsolar point (11:30 magnetic local time) and somewhat south of the geomagnetic equator (−33° magnetic latitude): (i) kinetic Alfvén waves; (ii) a peaking of the electric and magnetic field strengths where E·J becomes strong and negative (−1 nW/m3) just prior to an abrupt dropout of the fields; (iii) evolution in the pitch angle distribution of energetic (a few tens of kilo-electron-volts) ions (H+, Hen+, and On+) and electrons inside a high-density region, which we attribute to gyrosounding of the tangential discontinuity/vortex sheet structure passing by the spacecraft; (iv) field-aligned acceleration of ions and electrons that could be associated with localized magnetosheath reconnection inside the high-density region; and (v) variable and strong flow changes, which we argue to be unrelated to reconnection at partial magnetopause crossings and likely result from deflections of magnetosheath flow by a locally deformed, oscillating magnetopause.

Publication Date

8-30-2018

Journal Title

JGR: Space Physics

Publisher

AGU

Digital Object Identifier (DOI)

https://dx.doi.org/10.1029/2018JA025724

Document Type

Article

Recommended Citation

Effects in the Near-Magnetopause Magnetosheath Elicited by Large-Amplitube Alfvenic Fluctuations Terminating in a Field and Flow Discontinuity. Journal of Geophysical Research. 123:8983-9004. 2018