Ion Larmor radius effects near a reconnection X line at the magnetopause: THEMIS observations and simulation comparison

Abstract We report a Time History of Events and Macroscale Interactions during Substorms (THEMIS‐D) spacecraft crossing of a magnetopause reconnection exhaust ~9 ion skin depths (di) downstream of an X line. The crossing was characterized by ion jetting at speeds substantially below the predicted re...

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Main Authors: T. D. Phan, M. A. Shay, C. C. Haggerty, J. T. Gosling, J. P. Eastwood, M. Fujimoto, K. Malakit, F. S. Mozer, P. A. Cassak, M. Oieroset, V. Angelopoulos
Format: Article
Language:English
Published: Wiley 2016-09-01
Series:Geophysical Research Letters
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Online Access:https://doi.org/10.1002/2016GL070224
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author T. D. Phan
M. A. Shay
C. C. Haggerty
J. T. Gosling
J. P. Eastwood
M. Fujimoto
K. Malakit
F. S. Mozer
P. A. Cassak
M. Oieroset
V. Angelopoulos
author_facet T. D. Phan
M. A. Shay
C. C. Haggerty
J. T. Gosling
J. P. Eastwood
M. Fujimoto
K. Malakit
F. S. Mozer
P. A. Cassak
M. Oieroset
V. Angelopoulos
author_sort T. D. Phan
collection DOAJ
description Abstract We report a Time History of Events and Macroscale Interactions during Substorms (THEMIS‐D) spacecraft crossing of a magnetopause reconnection exhaust ~9 ion skin depths (di) downstream of an X line. The crossing was characterized by ion jetting at speeds substantially below the predicted reconnection outflow speed. In the magnetospheric inflow region THEMIS detected (a) penetration of magnetosheath ions and the resulting flows perpendicular to the reconnection plane, (b) ion outflow extending into the magnetosphere, and (c) enhanced electron parallel temperature. Comparison with a simulation suggests that these signatures are associated with the gyration of magnetosheath ions onto magnetospheric field lines due to the shift of the flow stagnation point toward the low‐density magnetosphere. Our observations indicate that these effects, ~2–3 di in width, extend at least 9 di downstream of the X line. The detection of these signatures could indicate large‐scale proximity of the X line but do not imply that the spacecraft was upstream of the electron diffusion region.
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spelling doaj-art-9c1e3e78cbd442d2a0b64c5096e8e2db2025-08-20T03:09:52ZengWileyGeophysical Research Letters0094-82761944-80072016-09-0143178844885210.1002/2016GL070224Ion Larmor radius effects near a reconnection X line at the magnetopause: THEMIS observations and simulation comparisonT. D. Phan0M. A. Shay1C. C. Haggerty2J. T. Gosling3J. P. Eastwood4M. Fujimoto5K. Malakit6F. S. Mozer7P. A. Cassak8M. Oieroset9V. Angelopoulos10Space Sciences Laboratory University of California Berkeley California USADepartment of Physics and Astronomy University of Delaware Newark Delaware USADepartment of Physics and Astronomy University of Delaware Newark Delaware USALaboratory for Atmospheric and Space Physics University of Colorado Boulder Boulder Colorado USAThe Blackett Laboratory Imperial College London London UKISAS/JAXA Kanagawa JapanDepartment of Physics Mahidol University Bangkok ThailandSpace Sciences Laboratory University of California Berkeley California USADepartment of Physics and Astronomy West Virginia University Morgantown West Virginia USASpace Sciences Laboratory University of California Berkeley California USADepartment of Earth, Planetary, and Space Sciences University of California Los Angeles California USAAbstract We report a Time History of Events and Macroscale Interactions during Substorms (THEMIS‐D) spacecraft crossing of a magnetopause reconnection exhaust ~9 ion skin depths (di) downstream of an X line. The crossing was characterized by ion jetting at speeds substantially below the predicted reconnection outflow speed. In the magnetospheric inflow region THEMIS detected (a) penetration of magnetosheath ions and the resulting flows perpendicular to the reconnection plane, (b) ion outflow extending into the magnetosphere, and (c) enhanced electron parallel temperature. Comparison with a simulation suggests that these signatures are associated with the gyration of magnetosheath ions onto magnetospheric field lines due to the shift of the flow stagnation point toward the low‐density magnetosphere. Our observations indicate that these effects, ~2–3 di in width, extend at least 9 di downstream of the X line. The detection of these signatures could indicate large‐scale proximity of the X line but do not imply that the spacecraft was upstream of the electron diffusion region.https://doi.org/10.1002/2016GL070224magnetic reconnectionmagnetopausediffusion region
spellingShingle T. D. Phan
M. A. Shay
C. C. Haggerty
J. T. Gosling
J. P. Eastwood
M. Fujimoto
K. Malakit
F. S. Mozer
P. A. Cassak
M. Oieroset
V. Angelopoulos
Ion Larmor radius effects near a reconnection X line at the magnetopause: THEMIS observations and simulation comparison
Geophysical Research Letters
magnetic reconnection
magnetopause
diffusion region
title Ion Larmor radius effects near a reconnection X line at the magnetopause: THEMIS observations and simulation comparison
title_full Ion Larmor radius effects near a reconnection X line at the magnetopause: THEMIS observations and simulation comparison
title_fullStr Ion Larmor radius effects near a reconnection X line at the magnetopause: THEMIS observations and simulation comparison
title_full_unstemmed Ion Larmor radius effects near a reconnection X line at the magnetopause: THEMIS observations and simulation comparison
title_short Ion Larmor radius effects near a reconnection X line at the magnetopause: THEMIS observations and simulation comparison
title_sort ion larmor radius effects near a reconnection x line at the magnetopause themis observations and simulation comparison
topic magnetic reconnection
magnetopause
diffusion region
url https://doi.org/10.1002/2016GL070224
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