Imperial College London

Dr Jonathan P. Eastwood

Faculty of Natural SciencesDepartment of Physics

Senior Lecturer
 
 
 
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Contact

 

+44 (0)20 7594 8101jonathan.eastwood Website

 
 
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Location

 

6M63Blackett LaboratorySouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
to

146 results found

Hesse M, Norgren C, Tenfjord P, Burch JL, Liu YH, Chen LJ, Bessho N, Wang S, Nakamura R, Eastwood JP, Hoshino M, Torbert RB, Ergun REet al., 2019, Erratum: On the role of separatrix instabilities in heating the reconnection outflow region (Physics of Plasmas (2018) 25 (122902) DOI: 10.1063/1.5054100), Physics of Plasmas, Vol: 26, ISSN: 1070-664X

© 2019 Author(s). In a recent paper1 about electron heating at the reconnection separatrix, two figures depicting the contributions to the electron energy balance and the contribution to the total, quasi-viscous heating are incorrectly displayed. The correct figures are as follows: [Table Presented].

JOURNAL ARTICLE

Øieroset M, Phan TD, Drake JF, Eastwood JP, Fuselier SA, Strangeway RJ, Haggerty C, Shay MA, Oka M, Wang S, Chen L-J, Kacem I, Lavraud B, Angelopoulos V, Burch JL, Torbert RB, Ergun RE, Khotyaintsev Y, Lindqvist PA, Gershman DJ, Giles BL, Pollock C, Moore TE, Russell CT, Saito Y, Avanov LA, Paterson Wet al., 2019, Reconnection with magnetic flux pileup at the interface of converging jets at the magnetopause, Geophysical Research Letters, Vol: 46, Pages: 1937-1946, ISSN: 0094-8276

We report Magnetospheric Multiscale observations of reconnection in a thin current sheet at the interface of interlinked flux tubes carried by converging reconnection jets at Earth's magnetopause. The ion skin depth‐scale width of the interface current sheet and the non‐frozen‐in ions indicate that Magnetospheric Multiscale crossed the reconnection layer near the X‐line, through the ion diffusion region. Significant pileup of the reconnecting component of the magnetic field in this and three other events on approach to the interface current sheet was accompanied by an increase in magnetic shear and decrease in Δβ, leading to conditions favorable for reconnection at the interface current sheet. The pileup also led to enhanced available magnetic energy per particle and strong electron heating. The observations shed light on the evolution and energy release in 3‐D systems with multiple reconnection sites.

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Gingell I, Schwartz SJ, Eastwood JP, Burch JL, Ergun RE, Fuselier S, Gershman DJ, Giles BL, Khotyaintsev Y, Lavraud B, Lindqvist P-A, Paterson WR, Phan TD, Russell CT, Stawarz JE, Strangeway RJ, Torbert RB, Wilder Fet al., 2019, Observations of Magnetic Reconnection in the Transition Region of Quasi-Parallel Shocks, GEOPHYSICAL RESEARCH LETTERS, Vol: 46, Pages: 1177-1184, ISSN: 0094-8276

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Nakamura R, Genestreti KJ, Nakamura T, Baumjohann W, Varsani A, Nagai T, Bessho N, Burch JL, Denton RE, Eastwood JP, Ergun RE, Gershman DJ, Giles BL, Hasegawa H, Hesse M, Lindqvist P-A, Russell CT, Stawarz JE, Strangeway RJ, Torbert RBet al., 2019, Structure of the current sheet in the 11 July 2017 Electron Diffusion Region Event, Journal of Geophysical Research: Space Physics, Vol: 124, Pages: 1173-1186, ISSN: 2169-9380

The structure of the current sheet along the Magnetospheric Multiscale (MMS) orbit is examined during the 11 July 2017 Electron Diffusion Region (EDR) event. The location of MMS relative to the X‐line is deduced and used to obtain the spatial changes in the electron parameters. The electron velocity gradient values are used to estimate the reconnection electric field sustained by nongyrotropic pressure. It is shown that the observations are consistent with theoretical expectations for an inner EDR in 2‐D reconnection. That is, the magnetic field gradient scale, where the electric field due to electron nongyrotropic pressure dominates, is comparable to the gyroscale of the thermal electrons at the edge of the inner EDR. Our approximation of the MMS observations using a steady state, quasi‐2‐D, tailward retreating X‐line was valid only for about 1.4 s. This suggests that the inner EDR is localized; that is, electron outflow jet braking takes place within an ion inertia scale from the X‐line. The existence of multiple events or current sheet processes outside the EDR may play an important role in the geometry of reconnection in the near‐Earth magnetotail.

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Torbert RB, Burch JL, Phan TD, Hesse M, Argall MR, Shuster J, Ergun RE, Alm L, Nakamura R, Genestreti KJ, Gershman DJ, Paterson WR, Turner DL, Cohen I, Giles BL, Pollock CJ, Wang S, Chen L-J, Stawarz JE, Eastwood JP, Hwang KJ, Farrugia C, Dors I, Vaith H, Mouikis C, Ardakani A, Mauk BH, Fuselier SA, Russell CT, Strangeway RJ, Moore TE, Drake JF, Shay MA, Khotyaintsev YV, Lindqvist P-A, Baumjohann W, Wilder FD, Ahmadi N, Dorelli JC, Avanov LA, Oka M, Baker DN, Fennell JF, Blake JB, Jaynes AN, Le Contel O, Petrinec SM, Lavraud B, Saito Yet al., 2018, Electron-scale dynamics of the diffusion region during symmetric magnetic reconnection in space., Science, Vol: 362, Pages: 1391-1395

Magnetic reconnection is an energy conversion process that occurs in many astrophysical contexts including Earth's magnetosphere, where the process can be investigated in situ by spacecraft. On 11 July 2017, the four Magnetospheric Multiscale spacecraft encountered a reconnection site in Earth's magnetotail, where reconnection involves symmetric inflow conditions. The electron-scale plasma measurements revealed (i) super-Alfvénic electron jets reaching 15,000 kilometers per second; (ii) electron meandering motion and acceleration by the electric field, producing multiple crescent-shaped structures in the velocity distributions; and (iii) the spatial dimensions of the electron diffusion region with an aspect ratio of 0.1 to 0.2, consistent with fast reconnection. The well-structured multiple layers of electron populations indicate that the dominant electron dynamics are mostly laminar, despite the presence of turbulence near the reconnection site.

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Eggington JWB, Mejnertsen L, Desai RT, Eastwood JP, Chittenden JPet al., 2018, Forging links in Earth's plasma environment, ASTRONOMY & GEOPHYSICS, Vol: 59, Pages: 26-28, ISSN: 1366-8781

JOURNAL ARTICLE

Hesse M, Norgren C, Tenfjord P, Burch JL, Liu Y-H, Chen L-J, Bessho N, Wang S, Nakamura R, Eastwood JP, Hoshino M, Torbert RB, Ergun REet al., 2018, On the role of separatrix instabilities in heating the reconnection outflow region, PHYSICS OF PLASMAS, Vol: 25, ISSN: 1070-664X

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Eastwood JP, Hapgood MA, Biffis E, Benedetti D, Bisi MM, Green L, Bentley RD, Burnett Cet al., 2018, Quantifying the Economic Value of Space Weather Forecasting for Power Grids: An Exploratory Study, SPACE WEATHER-THE INTERNATIONAL JOURNAL OF RESEARCH AND APPLICATIONS, Vol: 16, Pages: 2052-2067, ISSN: 1542-7390

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Hwang KJ, Sibeck DG, Burch JL, Choi E, Fear RC, Lavraud B, Giles BL, Gershman D, Pollock CJ, Eastwood JP, Khotyaintsev Y, Escoubet P, Fu H, Toledo-Redondo S, Torbert RB, Ergun RE, Paterson WR, Dorelli JC, Avanov L, Russell CT, Strangeway RJet al., 2018, Small-scale flux transfer events formed in the reconnection exhaust region between two X lines, Journal of Geophysical Research: Space Physics, Vol: 123, Pages: 8473-8488, ISSN: 2169-9380

We report MMS observations of the ion-scale flux transfer events (FTEs) that may involve two main X lines and tearing instability between the two X lines. The four spacecraft detected multiple isolated regions with enhanced magnetic field strength and bipolar Bn signatures normal to the nominal magnetopause, indicating FTEs. The currents within the FTEs flow mostly parallel to B, and the magnetic tension force is balanced by the total pressure gradient force. During these events, the plasma bulk flow velocity was directed southward. Detailed analysis of the magnetic and electric field and plasma moments variations suggests that the FTEs were initially embedded within the exhaust region north of an X line but were later located southward/downstream of a subsequent X line. The cross sections of the individual FTEs are in the range of ~2.5–6.8 ion inertial lengths. The observations suggest the formation of multiple secondary FTEs. The presence of an X line in the exhaust region southward of a second X line results from the southward drift of an old X line and the reformation of a new X line. The current layer between the two X lines is unstable to the tearing instability, generating multiple ion-scale flux-rope-type secondary islands.

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Schwartz SJ, Avanov L, Turner D, Zhang H, Gingell I, Eastwood JP, Gershman DJ, Johlander A, Russell CT, Burch JL, Dorelli JC, Eriksson S, Ergun RE, Fuselier SA, Giles BL, Goodrich KA, Khotyaintsev YV, Lavraud B, Lindqvist P-A, Oka M, Tai-Duc P, Strangeway RJ, Trattner KJ, Torbert RB, Vaivads A, Wei H, Wilder Fet al., 2018, Ion Kinetics in a Hot Flow Anomaly: MMS Observations, GEOPHYSICAL RESEARCH LETTERS, Vol: 45, Pages: 11520-11529, ISSN: 0094-8276

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Stawarz JE, Eastwood JP, Genestreti KJ, Nakamura R, Ergun RE, Burgess D, Burch JL, Fuselier SA, Gershman DJ, Giles BL, Le Contel O, Lindqvist P-A, Russell CT, Torbert RBet al., 2018, Intense Electric Fields and Electron-Scale Substructure Within Magnetotail Flux Ropes as Revealed by the Magnetospheric Multiscale Mission, GEOPHYSICAL RESEARCH LETTERS, Vol: 45, Pages: 8783-8792, ISSN: 0094-8276

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Eastwood JP, Mistry R, Phan TD, Schwartz SJ, Ergun RE, Drake JF, Oieroset M, Stawarz JE, Goldman MV, Haggerty C, Shay MA, Burch JL, Gershman DJ, Giles BL, Lindqvist PA, Torbert RB, Strangeway RJ, Russell CTet al., 2018, Guide Field Reconnection: Exhaust Structure and Heating, GEOPHYSICAL RESEARCH LETTERS, Vol: 45, Pages: 4569-4577, ISSN: 0094-8276

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Phan TD, Eastwood JP, Shay MA, Drake JF, Sonnerup BUO, Fujimoto M, Cassak PA, Øieroset M, Burch JL, Torbert RB, Rager AC, Dorelli JC, Gershman DJ, Pollock C, Pyakurel PS, Haggerty CC, Khotyaintsev Y, Lavraud B, Saito Y, Oka M, Ergun RE, Retino A, Le Contel O, Argall MR, Giles BL, Moore TE, Wilder FD, Strangeway RJ, Russell CT, Lindqvist PA, Magnes Wet al., 2018, Electron magnetic reconnection without ion coupling in Earth's turbulent magnetosheath, Nature, Vol: 557, Pages: 202-206, ISSN: 0028-0836

© 2018 Macmillan Publishers Ltd., part of Springer Nature. Magnetic reconnection in current sheets is a magnetic-to-particle energy conversion process that is fundamental to many space and laboratory plasma systems. In the standard model of reconnection, this process occurs in a minuscule electron-scale diffusion region 1,2 . On larger scales, ions couple to the newly reconnected magnetic-field lines and are ejected away from the diffusion region in the form of bi-directional ion jets at the ion Alfvén speed 3-5 . Much of the energy conversion occurs in spatially extended ion exhausts downstream of the diffusion region 6 . In turbulent plasmas, which contain a large number of small-scale current sheets, reconnection has long been suggested to have a major role in the dissipation of turbulent energy at kinetic scales 7-11 . However, evidence for reconnection plasma jetting in small-scale turbulent plasmas has so far been lacking. Here we report observations made in Earth's turbulent magnetosheath region (downstream of the bow shock) of an electron-scale current sheet in which diverging bi-directional super-ion-Alfvénic electron jets, parallel electric fields and enhanced magnetic-to-particle energy conversion were detected. Contrary to the standard model of reconnection, the thin reconnecting current sheet was not embedded in a wider ion-scale current layer and no ion jets were detected. Observations of this and other similar, but unidirectional, electron jet events without signatures of ion reconnection reveal a form of reconnection that can drive turbulent energy transfer and dissipation in electron-scale current sheets without ion coupling.

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Harrison RA, Davies JA, Barnes D, Byrne JP, Perry CH, Bothmer V, Eastwood JP, Gallagher PT, Kilpua EKJ, Moestl C, Rodriguez L, Rouillard AP, Odstril Det al., 2018, CMEs in the Heliosphere: I. A Statistical Analysis of the Observational Properties of CMEs Detected in the Heliosphere from 2007 to 2017 by STEREO/HI-1, Solar Physics, Vol: 293, ISSN: 0038-0938

We present a statistical analysis of coronal mass ejections (CMEs) imaged by the Heliospheric Imager (HI) instruments on board NASA’s twin-spacecraft STEREO mission between April 2007 and August 2017 for STEREO-A and between April 2007 and September 2014 for STEREO-B. The analysis exploits a catalogue that was generated within the FP7 HELCATS project. Here, we focus on the observational characteristics of CMEs imaged in the heliosphere by the inner (HI-1) cameras, while following papers will present analyses of CME propagation through the entire HI fields of view. More specifically, in this paper we present distributions of the basic observational parameters – namely occurrence frequency, central position angle (PA) and PA span – derived from nearly 2000 detections of CMEs in the heliosphere by HI-1 on STEREO-A or STEREO-B from the minimum between Solar Cycles 23 and 24 to the maximum of Cycle 24; STEREO-A analysis includes a further 158 CME detections from the descending phase of Cycle 24, by which time communication with STEREO-B had been lost. We compare heliospheric CME characteristics with properties of CMEs observed at coronal altitudes, and with sunspot number. As expected, heliospheric CME rates correlate with sunspot number, and are not inconsistent with coronal rates once instrumental factors/differences in cataloguing philosophy are considered. As well as being more abundant, heliospheric CMEs, like their coronal counterparts, tend to be wider during solar maximum. Our results confirm previous coronagraph analyses suggesting that CME launch sites do not simply migrate to higher latitudes with increasing solar activity. At solar minimum, CMEs tend to be launched from equatorial latitudes, while at maximum, CMEs appear to be launched over a much wider latitude range; this has implications for understanding the CME/solar source association. Our analysis provides some supporting evidence for the systematic dragging of CMEs to lower latitude

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Krupar V, Maksimovic M, Kontar EP, Zaslavsky A, Santolik O, Soucek J, Kruparova O, Eastwood JP, Szabo Aet al., 2018, Interplanetary Type III Bursts and Electron Density Fluctuations in the Solar Wind, ASTROPHYSICAL JOURNAL, Vol: 857, ISSN: 0004-637X

Type III bursts are generated by fast electron beams originated from magnetic reconnection sites of solar flares. As propagation of radio waves in the interplanetary medium is strongly affected by random electron density fluctuations, type III bursts provide us with a unique diagnostic tool for solar wind remote plasma measurements. Here, we performed a statistical survey of 152 simple and isolated type III bursts observed by the twin-spacecraft Solar TErrestrial RElations Observatory mission. We investigated their time–frequency profiles in order to retrieve decay times as a function of frequency. Next, we performed Monte Carlo simulations to study the role of scattering due to random electron density fluctuations on time–frequency profiles of radio emissions generated in the interplanetary medium. For simplification, we assumed the presence of isotropic electron density fluctuations described by a power law with the Kolmogorov spectral index. Decay times obtained from observations and simulations were compared. We found that the characteristic exponential decay profile of type III bursts can be explained by the scattering of the fundamental component between the source and the observer despite restrictive assumptions included in the Monte Carlo simulation algorithm. Our results suggest that relative electron density fluctuations $\langle \delta {n}_{{\rm{e}}}\rangle /{n}_{{\rm{e}}}$ in the solar wind are 0.06–0.07 over wide range of heliospheric distances.

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Ergun RE, Goodrich KA, Wilder FD, Ahmadi N, Holmes JC, Eriksson S, Stawarz JE, Nakamura R, Genestreti KJ, Hesse M, Burch JL, Torbert RB, Phan TD, Schwartz SJ, Eastwood JP, Strangeway RJ, Le Contel O, Russell CT, Argall MR, Lindqvist PA, Chen LJ, Cassak PA, Giles BL, Dorelli JC, Gershman D, Leonard TW, Lavraud B, Retino A, Matthaeus W, Vaivads Aet al., 2018, Magnetic Reconnection, Turbulence, and Particle Acceleration: Observations in the Earth's Magnetotail, Geophysical Research Letters, Vol: 45, Pages: 3338-3347, ISSN: 0094-8276

We report observations of turbulent dissipation and particle acceleration from large-amplitude electric fields (E) associated with strong magnetic field (B) fluctuations in the Earth's plasma sheet. The turbulence occurs in a region of depleted density with anti-earthward flows followed by earthward flows suggesting ongoing magnetic reconnection. In the turbulent region, ions and electrons have a significant increase in energy, occasionally > 100 keV, and strong variation. There are numerous occurrences of |E| > 100 mV/m including occurrences of large potentials ( > 1 kV) parallel to B and occurrences with extraordinarily large J · E (J is current density). In this event, we find that the perpendicular contribution of J · E with frequencies near or below the ion cyclotron frequency (f ci ) provide the majority net positive J · E. Large-amplitude parallel E events with frequencies above f ci to several times the lower hybrid frequency provide significant dissipation and can result in energetic electron acceleration.

JOURNAL ARTICLE

Genestreti KJ, Varsani A, Burch JL, Cassak PA, Torbert RB, Nakamura R, Ergun RE, Phan TD, Toledo-Redondo S, Hesse M, Wang S, Giles BL, Russell CT, Vörös Z, Hwang KJ, Eastwood JP, Lavraud B, Escoubet CP, Fear RC, Khotyaintsev Y, Nakamura TKM, Webster JM, Baumjohann Wet al., 2018, MMS observation of asymmetric reconnection supported by 3-D electron pressure divergence, Journal of Geophysical Research: Space Physics, Vol: 123, Pages: 1806-1821, ISSN: 2169-9380

We identify the electron diffusion region (EDR) of a guide field dayside reconnection site encountered by the Magnetospheric Multiscale (MMS) mission and estimate the terms in generalized Ohm's law that controlled energy conversion near the X-point. MMS crossed the moderate-shear (∼130°) magnetopause southward of the exact X-point. MMS likely entered the magnetopause far from the X-point, outside the EDR, as the size of the reconnection layer was less than but comparable to the magnetosheath proton gyroradius, and also as anisotropic gyrotropic "outflow" crescent electron distributions were observed. MMS then approached the X-point, where all four spacecraft simultaneously observed signatures of the EDR, for example, an intense out-of-plane electron current, moderate electron agyrotropy, intense electron anisotropy, nonideal electric fields, and nonideal energy conversion. We find that the electric field associated with the nonideal energy conversion is (a) well described by the sum of the electron inertial and pressure divergence terms in generalized Ohms law though (b) the pressure divergence term dominates the inertial term by roughly a factor of 5:1, (c) both the gyrotropic and agyrotropic pressure forces contribute to energy conversion at the X-point, and (d) both out-of-the-reconnection-plane gradients (∂/∂M) and in-plane (∂/∂L,N) in the pressure tensor contribute to energy conversion near the X-point. This indicates that this EDR had some electron-scale structure in the out-of-plane direction during the time when (and at the location where) the reconnection site was observed.

JOURNAL ARTICLE

Kacem I, Jacquey C, Génot V, Lavraud B, Vernisse Y, Marchaudon A, Le Contel O, Breuillard H, Phan TD, Hasegawa H, Oka M, Trattner KJ, Farrugia CJ, Paulson K, Eastwood JP, Fuselier SA, Turner D, Eriksson S, Wilder F, Russell CT, Øieroset M, Burch J, Graham DB, Sauvaud JA, Avanov L, Chandler M, Coffey V, Dorelli J, Gershman DJ, Giles BL, Moore TE, Saito Y, Chen LJ, Penou Eet al., 2018, Magnetic reconnection at a thin current sheet separating two interlaced flux tubes at the Earth's magnetopause, Journal of Geophysical Research: Space Physics, Vol: 123, Pages: 1779-1793, ISSN: 2169-9380

The occurrence of spatially and temporally variable reconnection at the Earth's magnetopause leads to the complex interaction of magnetic fields from the magnetosphere and magnetosheath. Flux transfer events (FTEs) constitute one such type of interaction. Their main characteristics are (1) an enhanced core magnetic field magnitude and (2) a bipolar magnetic field signature in the component normal to the magnetopause, reminiscent of a large-scale helicoidal flux tube magnetic configuration. However, other geometrical configurations which do not fit this classical picture have also been observed. Using high-resolution measurements from the Magnetospheric Multiscale mission, we investigate an event in the vicinity of the Earth's magnetopause on 7 November 2015. Despite signatures that, at first glance, appear consistent with a classic FTE, based on detailed geometrical and dynamical analyses as well as on topological signatures revealed by suprathermal electron properties, we demonstrate that this event is not consistent with a single, homogenous helicoidal structure. Our analysis rather suggests that it consists of the interaction of two separate sets of magnetic field lines with different connectivities. This complex three-dimensional interaction constructively conspires to produce signatures partially consistent with that of an FTE. We also show that, at the interface between the two sets of field lines, where the observed magnetic pileup occurs, a thin and strong current sheet forms with a large ion jet, which may be consistent with magnetic flux dissipation through magnetic reconnection in the interaction region.

JOURNAL ARTICLE

Good SW, Forsyth RJ, Eastwood JP, Moestl Cet al., 2018, y Correlation of ICME Magnetic Fields at Radially Aligned Spacecraft, SOLAR PHYSICS, Vol: 293, ISSN: 0038-0938

JOURNAL ARTICLE

Akhavan-Tafti M, Slavin JA, Le G, Eastwood JP, Strangeway RJ, Russell CT, Nakamura R, Baumjohann W, Torbert RB, Giles BL, Gershman DJ, Burch JLet al., 2018, MMS examination of FTEs at the earth's subsolar magnetopause, Journal of Geophysical Research: Space Physics, Vol: 123, Pages: 1224-1241, ISSN: 2169-9380

Determining the magnetic field structure, electric currents, and plasma distributions within flux transfer event (FTE)-type flux ropes is critical to the understanding of their origin, evolution, and dynamics. Here the Magnetospheric Multiscale mission's high-resolution magnetic field and plasma measurements are used to identify FTEs in the vicinity of the subsolar magnetopause. The constant-α flux rope model is used to identify quasi-force free flux ropes and to infer the size, the core magnetic field strength, the magnetic flux content, and the spacecraft trajectories through these structures. Our statistical analysis determines a mean diameter of 1,700 ± 400 km (~30 ± 9 d i ) and an average magnetic flux content of 100 ± 30 kWb for the quasi-force free FTEs at the Earth's subsolar magnetopause which are smaller than values reported by Cluster at high latitudes. These observed nonlinear size and magnetic flux content distributions of FTEs appear consistent with the plasmoid instability theory, which relies on the merging of neighboring, small-scale FTEs to generate larger structures. The ratio of the perpendicular to parallel components of current density, R J , indicates that our FTEs are magnetically force-free, defined as R J < 1, in their core regions ( < 0.6 R flux rope ). Plasma density is shown to be larger in smaller, newly formed FTEs and dropping with increasing FTE size. It is also shown that parallel ion velocity dominates inside FTEs with largest plasma density. Field-aligned flow facilitates the evacuation of plasma inside newly formed FTEs, while their core magnetic field strengthens with increasing FTE size.

JOURNAL ARTICLE

Mejnertsen L, Eastwood JP, Hietala H, Schwartz SJ, Chittenden JPet al., 2018, Global MHD Simulations of the Earth's Bow Shock Shape and Motion Under Variable Solar Wind Conditions, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 123, Pages: 259-271, ISSN: 2169-9380

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Eastwood JP, Nakamura R, Turc L, Mejnertsen L, Hesse Met al., 2017, The Scientific Foundations of Forecasting Magnetospheric Space Weather, SPACE SCIENCE REVIEWS, Vol: 212, Pages: 1221-1252, ISSN: 0038-6308

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Farrugia CJ, Lugaz N, Alm L, Vasquez B, Argall MR, Kucharek H, Matsui H, Torbert RB, Lavraud B, LeContel O, Cohen IJ, Burch JL, Russell CT, Strangeway RJ, Shuster J, Dorelli JC, Eastwood JP, Ergun RE, Fuselier SA, Gershman DJ, Giles BL, Khotyaintsev YV, Lindqvist PA, Marklund GT, Paulson KW, Petrinec SM, Phan TD, Pollock CJet al., 2017, MMS Observations of Reconnection at Dayside Magnetopause Crossings During Transitions of the Solar Wind to Sub-Alfvénic Flow, Journal of Geophysical Research: Space Physics, Vol: 122, Pages: 9934-9951, ISSN: 2169-9380

We present MMS observations during two dayside magnetopause crossings under hithertounexamined conditions: (i) when the bow shock is weakening and the solar wind transitioning tosub-Alfvénic flow and (ii) when it is reforming. Interplanetary conditions consist of a magnetic cloud with (i)a strongB(∼20 nT) pointing south and (ii) a density profile with episodic decreases to values of∼0.3 cm−3followed by moderate recovery. During the crossings the magnetosheath magnetic field is stronger thanthe magnetosphere field by a factor of∼2.2. As a result, during the outbound crossing through the iondiffusion region, MMS observed an inversion of the relative positions of the X and stagnation (S) lines fromthat typically the case: the S line was closer to the magnetosheath side. The S line appears in the form of aslow expansion fan near which most of the energy dissipation is taking place. While in the magnetospherebetween the crossings, MMS observed strong field and flow perturbations, which we argue to be due tokinetic Alfvén waves. During the reconnection interval, whistler mode waves generated by an electrontemperature anisotropy (Te⟂>Te∥) were observed. Another aim of the paper is to distinguish bowshock-induced field and flow perturbations from reconnection-related signatures. The high-resolutionMMS data together with 2-D hybrid simulations of bow shock dynamics helped us to distinguish betweenthe two sources. We show examples of bow shock-related effects (such as heating) and reconnectioneffects such as accelerated flows satisfying the Walén relation.

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Øieroset M, Phan TD, Shay MA, Haggerty CC, Fujimoto M, Angelopoulos V, Eastwood JP, Mozer FSet al., 2017, THEMIS multispacecraft observations of a reconnecting magnetosheath current sheet with symmetric boundary conditions and a large guide field, Geophysical Research Letters, Vol: 44, Pages: 7598-7606, ISSN: 0094-8276

We report three spacecraft observations of a reconnecting magnetosheath current sheet with a guide field of unity, with THEMIS D (THD) and THEMIS E (THE)/THEMIS A (THA) observing oppositely directed reconnection exhausts, indicating the presence of an X line between the spacecraft. The near-constant convective speed of the magnetosheath current sheet allowed the direct translation of the observed time series into spatial profiles. THD observed asymmetries in the plasma density and temperature profiles across the exhaust, characteristics of symmetric reconnection with a guide field. The exhausts at THE and THA, on the other hand, were not the expected mirror image of the THD exhaust in terms of the plasma and field profiles. They consisted of a main outflow at the center of the current sheet, flanked by oppositely directed flows at the two edges of the current sheet, suggesting the presence of a second X line, whose outflow wraps around the outflow from the first X line.

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Moestl C, Isavnin A, Boakes PD, Kilpua EKJ, Davies JA, Harrison RA, Barnes D, Krupar V, Eastwood JP, Good SW, Forsyth RJ, Bothmer V, Reiss MA, Amerstorfer T, Winslow RM, Anderson BJ, Philpott LC, Rodriguez L, Rouillard AP, Gallagher P, Nieves-Chinchilla T, Zhang TLet al., 2017, Modeling observations of solar coronal mass ejections with heliospheric imagers verified with the Heliophysics System Observatory, Space Weather-the International Journal of Research and Applications, Vol: 15, Pages: 955-970, ISSN: 1539-4956

We present an advance toward accurately predicting the arrivals of coronal mass ejections (CMEs) at the terrestrial planets, including Earth. For the first time, we are able to assess a CME prediction model using data over two thirds of a solar cycle of observations with the Heliophysics System Observatory. We validate modeling results of 1337 CMEs observed with the Solar Terrestrial Relations Observatory (STEREO) heliospheric imagers (HI) (science data) from 8 years of observations by five in situ observing spacecraft. We use the self-similar expansion model for CME fronts assuming 60° longitudinal width, constant speed, and constant propagation direction. With these assumptions we find that 23%–35% of all CMEs that were predicted to hit a certain spacecraft lead to clear in situ signatures, so that for one correct prediction, two to three false alarms would have been issued. In addition, we find that the prediction accuracy does not degrade with the HI longitudinal separation from Earth. Predicted arrival times are on average within 2.6 ± 16.6 h difference of the in situ arrival time, similar to analytical and numerical modeling, and a true skill statistic of 0.21. We also discuss various factors that may improve the accuracy of space weather forecasting using wide-angle heliospheric imager observations. These results form a first-order approximated baseline of the prediction accuracy that is possible with HI and other methods used for data by an operational space weather mission at the Sun-Earth L5 point.

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Stawarz JE, Eastwood JP, Varsani A, Ergun RE, Shay MA, Nakamura R, Phan TD, Burch JL, Gershman DJ, Giles BL, Goodrich KA, Khotyaintsev YV, Lindqvist P-A, Russell CT, Strangeway RJ, Torbert RBet al., 2017, Magnetospheric Multiscale analysis of intense field-aligned Poynting flux near the Earth's plasma sheet boundary, GEOPHYSICAL RESEARCH LETTERS, Vol: 44, Pages: 7106-7113, ISSN: 0094-8276

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Mistry R, Eastwood JP, Phan TD, Hietala Het al., 2017, Statistical properties of solar wind reconnection exhausts, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 122, Pages: 5895-5909, ISSN: 2169-9380

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Innocenti ME, Cazzola E, Mistry R, Eastwood JP, Goldman MV, Newman DL, Markidis S, Lapenta Get al., 2017, Switch-off slow shock/rotational discontinuity structures in collisionless magnetic reconnection: What to look for in satellite observations, GEOPHYSICAL RESEARCH LETTERS, Vol: 44, Pages: 3447-3455, ISSN: 0094-8276

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Ergun RE, Chen L-J, Wilder FD, Ahmadi N, Eriksson S, Usanova ME, Goodrich KA, Holmes JC, Sturner AP, Malaspina DM, Newman DL, Torbert RB, Argall MR, Lindqvist P-A, Burch JL, Webster JM, Drake JF, Price L, Cassak PA, Swisdak M, Shay MA, Graham DB, Strangeway RJ, Russell CT, Giles BL, Dorelli JC, Gershman D, Avanov L, Hesse M, Lavraud B, Le Contel O, Retino A, Phan TD, Goldman MV, Stawarz JE, Schwartz SJ, Eastwood JP, Hwang K-J, Nakamura R, Wang Set 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

JOURNAL ARTICLE

Eastwood JP, Biffis E, Hapgood MA, Green L, Bisi MM, Bentley RD, Wicks R, McKinnell L-A, Gibbs M, Burnett Cet al., 2017, The Economic Impact of Space Weather: Where Do We Stand?, RISK ANALYSIS, Vol: 37, Pages: 206-218, ISSN: 0272-4332

JOURNAL ARTICLE

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