New Insights into the Nature of Turbulence in the Earth's Magnetosheath Using Magnetospheric MultiScale Mission Data
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Author(s)
Type
Journal Article
Abstract
The Earth's magnetosheath, which is characterized by highly turbulent fluctuations, is usually divided into two regions of different properties as a function of the angle between the interplanetary magnetic field and the shock normal. In this study, we make use of high-time resolution instruments on board the Magnetospheric MultiScale spacecraft to determine and compare the properties of subsolar magnetosheath turbulence in both regions, i.e., downstream of the quasi-parallel and quasi-perpendicular bow shocks. In particular, we take advantage of the unprecedented temporal resolution of the Fast Plasma Investigation instrument to show the density fluctuations down to sub-ion scales for the first time. We show that the nature of turbulence is highly compressible down to electron scales, particularly in the quasi-parallel magnetosheath. In this region, the magnetic turbulence also shows an inertial (Kolmogorov-like) range, indicating that the fluctuations are not formed locally, in contrast with the quasi-perpendicular magnetosheath. We also show that the electromagnetic turbulence is dominated by electric fluctuations at sub-ion scales (f > 1 Hz) and that magnetic and electric spectra steepen at the largest-electron scale. The latter indicates a change in the nature of turbulence at electron scales. Finally, we show that the electric fluctuations around the electron gyrofrequency are mostly parallel in the quasi-perpendicular magnetosheath, where intense whistlers are observed. This result suggests that energy dissipation, plasma heating, and acceleration might be driven by intense electrostatic parallel structures/waves, which can be linked to whistler waves.
Date Issued
2018-06-01
Date Acceptance
2018-03-18
Citation
ASTROPHYSICAL JOURNAL, 2018, 859 (2)
ISSN
0004-637X
Publisher
IOP PUBLISHING LTD
Journal / Book Title
ASTROPHYSICAL JOURNAL
Volume
859
Issue
2
Copyright Statement
© 2018 The American Astronomical Society. All rights reserved.
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000433938500026&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Subjects
Science & Technology
Physical Sciences
Astronomy & Astrophysics
acceleration of particles
Earth
planets and satellites: magnetic fields
plasmas
turbulence
waves
LOW-FREQUENCY WAVES
MAGNETIC-FIELD FLUCTUATIONS
BOW SHOCK
SOLAR-WIND
INERTIAL-RANGE
GYRATING IONS
SPECTRA
FORESHOCK
MHD
MMS
Publication Status
Published
Article Number
ARTN 127
Date Publish Online
2018-05-30