121 results found
Mistry R, Eastwood JP, Phan TD, et al., Statistical properties of solar wind reconnection exhausts, Journal of Geophysical Research: Space Physics, ISSN: 2169-9380
Eastwood JP, Biffis E, Hapgood MA, et al., 2017, The Economic Impact of Space Weather: Where Do We Stand?, RISK ANALYSIS, Vol: 37, Pages: 206-218, ISSN: 0272-4332
Ergun RE, Chen L-J, Wilder FD, et al., 2017, Drift waves, intense parallel electric fields, and turbulence associated with asymmetric magnetic reconnection at the magnetopause, GEOPHYSICAL RESEARCH LETTERS, Vol: 44, Pages: 2978-2986, ISSN: 0094-8276
Fu HS, Vaivads A, Khotyaintsev YV, et al., 2017, Intermittent energy dissipation by turbulent reconnection, Geophysical Research Letters, Vol: 44, Pages: 37-43, ISSN: 0094-8276
©2016. American Geophysical Union. All Rights Reserved.Magnetic reconnection—the process responsible for many explosive phenomena in both nature and laboratory—is efficient at dissipating magnetic energy into particle energy. To date, exactly how this dissipation happens remains unclear, owing to the scarcity of multipoint measurements of the “diffusion region” at the sub-ion scale. Here we report such a measurement by Cluster—four spacecraft with separation of 1/5 ion scale. We discover numerous current filaments and magnetic nulls inside the diffusion region of magnetic reconnection, with the strongest currents appearing at spiral nulls (O-lines) and the separatrices. Inside each current filament, kinetic-scale turbulence is significantly increased and the energy dissipation, E′ ⋅ j, is 100 times larger than the typical value. At the jet reversal point, where radial nulls (X-lines) are detected, the current, turbulence, and energy dissipations are surprisingly small. All these features clearly demonstrate that energy dissipation in magnetic reconnection occurs at O-lines but not X-lines.
Innocenti ME, Cazzola E, Mistry R, et al., 2017, Switch-off slow shock/rotational discontinuity structures in collisionless magnetic reconnection: What to look for in satellite observations, Geophysical Research Letters, ISSN: 0094-8276
©2017. American Geophysical Union.In Innocenti et al. (2015) we have observed and characterized for the first time Petschek-like switch-off slow shock/rotational discontinuity (SO-SS/RD) compound structures in a 2-D fully kinetic simulation of collisionless magnetic reconnection. Observing these structures in the solar wind or in the magnetotail would corroborate the possibility that Petschek exhausts develop in collisionless media as a result of single X point collisionless reconnection. Here we highlight their signatures in simulations with the aim of easing their identification in observations. The most notable signatures include a four-peaked ion current profile in the out-of-plane direction, associated ion distribution functions, increased electron and ion anisotropy downstream the SS, and increased electron agyrotropy downstream the RDs.
Arridge CS, Eastwood JP, Jackman CM, et al., 2016, Cassini in situ observations of long-duration magnetic reconnection in Saturn's magnetotail, NATURE PHYSICS, Vol: 12, Pages: 268-271, ISSN: 1745-2473
Burch JL, Torbert RB, Phan TD, et al., 2016, Electron-scale measurements of magnetic reconnection in space, SCIENCE, Vol: 352, ISSN: 0036-8075
Eastwood JP, Phan TD, Cassak PA, et al., 2016, Ion-scale secondary flux ropes generated by magnetopause reconnection as resolved by MMS, GEOPHYSICAL RESEARCH LETTERS, Vol: 43, Pages: 4716-4724, ISSN: 0094-8276
Ergun RE, Goodrich KA, Wilder FD, et al., 2016, Magnetospheric Multiscale Satellites Observations of Parallel Electric Fields Associated with Magnetic Reconnection, PHYSICAL REVIEW LETTERS, Vol: 116, ISSN: 0031-9007
Ergun RE, Holmes JC, Goodrich KA, et al., 2016, Magnetospheric Multiscale observations of large-amplitude, parallel, electrostatic waves associated with magnetic reconnection at the magnetopause, GEOPHYSICAL RESEARCH LETTERS, Vol: 43, Pages: 5626-5634, ISSN: 0094-8276
Farrugia CJ, Lavraud B, Torbert RB, et al., 2016, Magnetospheric Multiscale Mission observations and non-force free modeling of a flux transfer event immersed in a super-Alfvenic flow, GEOPHYSICAL RESEARCH LETTERS, Vol: 43, Pages: 6070-6077, ISSN: 0094-8276
Krupar V, Eastwood JP, Kruparova O, et al., 2016, AN ANALYSIS OF INTERPLANETARY SOLAR RADIO EMISSIONS ASSOCIATED WITH A CORONAL MASS EJECTION, ASTROPHYSICAL JOURNAL LETTERS, Vol: 823, ISSN: 2041-8205
Kubicka M, Möstl C, Amerstorfer T, et al., 2016, PREDICTION of GEOMAGNETIC STORM STRENGTH from INNER HELIOSPHERIC in SITU OBSERVATIONS, Astrophysical Journal, Vol: 833, ISSN: 0004-637X
© 2016. The American Astronomical Society. All rights reserved.Prediction of the effects of coronal mass ejections (CMEs) on Earth strongly depends on knowledge of the interplanetary magnetic field southward component, Bz. Predicting the strength and duration of Bz inside a CME with sufficient accuracy is currently impossible, forming the so-called Bz problem. Here, we provide a proof-of-concept of a new method for predicting the CME arrival time, speed, Bz, and resulting disturbance storm time (Dst) index on Earth based only on magnetic field data, measured in situ in the inner heliosphere (<1 au). On 2012 June 12-16, three approximately Earthward-directed and interacting CMEs were observed by the Solar Terrestrial Relations Observatory imagers and Venus Express (VEX) in situ at 0.72 au, 6° away from the Sun-Earth line. The CME kinematics are calculated using the drag-based and WSA-Enlil models, constrained by the arrival time at VEX, resulting in the CME arrival time and speed on Earth. The CME magnetic field strength is scaled with a power law from VEX to Wind. Our investigation shows promising results for the Dst forecast (predicted: -96 and -114 nT (from 2 Dst models); observed: -71 nT), for the arrival speed (predicted: 531 ±23 km s-1; observed: 488 ±30 km s-1), and for the timing (6 ±1 hr after the actual arrival time). The prediction lead time is 21 hr. The method may be applied to vector magnetic field data from a spacecraft at an artificial Lagrange point between the Sun and Earth or to data taken by any spacecraft temporarily crossing the Sun-Earth line.
Lavraud B, Liu Y, Segura K, et al., 2016, A small mission concept to the Sun-Earth Lagrangian L5 point for innovative solar, heliospheric and space weather science, JOURNAL OF ATMOSPHERIC AND SOLAR-TERRESTRIAL PHYSICS, Vol: 146, Pages: 171-185, ISSN: 1364-6826
Lavraud B, Zhang YC, Vernisse Y, et al., 2016, Currents and associated electron scattering and bouncing near the diffusion region at Earth's magnetopause, GEOPHYSICAL RESEARCH LETTERS, Vol: 43, Pages: 3042-3050, ISSN: 0094-8276
Mistry R, Eastwood JP, Haggerty CC, et al., 2016, Observations of Hall Reconnection Physics Far Downstream of the X Line, PHYSICAL REVIEW LETTERS, Vol: 117, ISSN: 0031-9007
Oieroset M, Phan TD, Haggerty C, et al., 2016, MMS observations of large guide field symmetric reconnection between colliding reconnection jets at the center of a magnetic flux rope at the magnetopause, GEOPHYSICAL RESEARCH LETTERS, Vol: 43, Pages: 5536-5544, ISSN: 0094-8276
Phan TD, Eastwood JP, Cassak PA, et al., 2016, MMS observations of electron-scale filamentary currents in the reconnection exhaust and near the X line, GEOPHYSICAL RESEARCH LETTERS, Vol: 43, Pages: 6060-6069, ISSN: 0094-8276
Phan TD, Shay MA, Eastwood JP, et al., 2016, Establishing the Context for Reconnection Diffusion Region Encounters and Strategies for the Capture and Transmission of Diffusion Region Burst Data by MMS, Space Science Reviews, Vol: 199, Pages: 631-650, ISSN: 0038-6308
© 2015, The Author(s).This paper describes the efforts of our Inter-Disciplinary Scientist (IDS) team to (a) establish the large-scale context for reconnection diffusion region encounters by MMS at the magnetopause and in the magnetotail, including the distinction between X-line and O-line encounters, that would help the identification of diffusion regions in spacecraft data, and (b) devise possible strategies that can be used by MMS to capture and transmit burst data associated with diffusion region candidates. At the magnetopause we suggest the strategy of transmitting burst data from all magnetopause crossings so that no magnetopause reconnection diffusion regions encountered by the spacecraft will be missed. The strategy is made possible by the MMS mass memory and downlink budget. In the magnetotail, it is estimated that MMS will be able to transmit burst data for all diffusion regions, all reconnection jet fronts (a.k.a. dipolarization fronts) and separatrix encounters, but less than 50 % of reconnection exhausts encountered by the spacecraft. We also discuss automated burst trigger schemes that could capture various reconnection-related phenomena. The identification of candidate diffusion region encounters by the burst trigger schemes will be verified and improved by a Scientist-In-The-Loop (SITL). With the knowledge of the properties of the region surrounding the diffusion region and the combination of automated burst triggers and further optimization by the SITL, MMS should be able to capture most diffusion regions it encounters.
Phan TD, Shay MA, Haggerty CC, et al., 2016, Ion Larmor radius effects near a reconnection X line at the magnetopause: THEMIS observations and simulation comparison, Geophysical Research Letters, Vol: 43, Pages: 8844-8852, ISSN: 0094-8276
©2016. American Geophysical Union. All Rights Reserved.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.
Plotnikov I, Rouillard AP, Davies JA, et al., 2016, Long-Term Tracking of Corotating Density Structures Using Heliospheric Imaging, SOLAR PHYSICS, Vol: 291, Pages: 1853-1875, ISSN: 0038-0938
Stawarz JE, Eriksson S, Wilder FD, et al., 2016, Observations of turbulence in a Kelvin-Helmholtz event on 8 September 2015 by the Magnetospheric Multiscale mission, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 121, Pages: 11021-11034, ISSN: 2169-9380
Vaivads A, Retino A, Soucek J, et al., 2016, Turbulence Heating ObserveR - satellite mission proposal, JOURNAL OF PLASMA PHYSICS, Vol: 82, ISSN: 0022-3778
Archer MO, Horbury TS, Brown P, et al., 2015, The MAGIC of CINEMA: first in-flight science results from a miniaturised anisotropic magnetoresistive magnetometer, ANNALES GEOPHYSICAE, Vol: 33, Pages: 725-735, ISSN: 0992-7689
Balogh A, Bykov A, Eastwood J, et al., 2015, Multi-scale Structure Formation and Dynamics in Cosmic Plasmas, SPACE SCIENCE REVIEWS, Vol: 188, Pages: 1-2, ISSN: 0038-6308
Eastwood JP, 2015, Observing magnetic reconnection: The influence of Jim Dungey, Pages: 181-197, ISBN: 9783319183589
© Springer International Publishing Switzerland 2015.As part of the Festspiel celebrating the 90th birthday of Prof. Jim Dungey, this paper reviews his influence on experimental efforts to observe reconnection in space plasmas. Jim has influenced this area of research in two key ways: firstly, in the development of theories of magnetic reconnection and secondly, in being an early and vocal advocate of the need for multi-point observations. The advent of multi-point missions such as Cluster and THEMIS in the past decade has enabled considerable progress, and we illustrate with examples how multi-point data and techniques have indeed improved our understanding of how reconnection works.
Eastwood JP, Goldman MV, Hietala H, et al., 2015, Ion reflection and acceleration near magnetotail dipolarization fronts associated with magnetic reconnection, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 120, Pages: 511-525, ISSN: 2169-9380
Eastwood JP, Hietala H, Toth G, et al., 2015, What Controls the Structure and Dynamics of Earth's Magnetosphere?, SPACE SCIENCE REVIEWS, Vol: 188, Pages: 251-286, ISSN: 0038-6308
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