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31 results on '"M. R. Argall"'

1. MMS Observations of Oscillating Energy Conversion and Electron Vorticity in an Electron‐Scale Layer Within a Southward Magnetopause Reconnection Exhaust

Author

S. Eriksson, N. Ahmadi, J. L. Burch, K. J. Genestreti, M. Swisdak, M. R. Argall, and D. L. Newman

Subjects
electron flow vortex, electron Kelvin‐Helmholtz instability, energy conversion, Geophysics. Cosmic physics, QC801-809
Abstract

Abstract The MMS satellites traversed a ∼6 di‐wide and ∼500 km/s southward reconnection exhaust at the dayside magnetopause on 6 December 2015 and ∼29 di from the associated X‐line region. A narrow ∼0.26–0.34 di layer of enhanced ±3.5 nW/m3 oscillating energy conversion perpendicular to the magnetic field resides in this exhaust. It contained two regions of diverging in‐plane electric fields in general agreement with two clockwise electron flow vortices and a proposed increase of the electron vorticity ∇ × Ve. The layer developed sunward of a unipolar Hall magnetic field for a duskward BM/BL ∼ 0.9 guide field. Each electron flow vortex supported a local ∆BM ∼ 10 nT strengthening of this Hall field. The presence of this electron‐scale layer in a southward exhaust for a duskward guide field is consistent with a two‐dimensional simulation of a similar structure that evolved from an X‐line into a northward exhaust for a similar strength dawnward guide field.

Published
2024
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2. Global Magnetic Reconnection During Sustained Sub‐Alfvénic Solar Wind Driving

Author

B. L. Burkholder, L.‐J. Chen, M. Sarantos, D. J. Gershman, M. R. Argall, Y. Chen, C. Dong, F. D. Wilder, O. Le Contel, and H. Gurram

Subjects
sub Alfvenic Solar wind, global reconnection, numerical simulation, Geophysics. Cosmic physics, QC801-809
Abstract

Abstract When the solar wind speed falls below the local Alfvén speed, the magnetotail transforms into an Alfvén wing configuration. A Grid Agnostic Magnetohydrodynamics for Extended Research Applications (GAMERA) simulation of Earth's magnetosphere using solar wind parameters from the 24 April 2023 sub‐Alfvénic interval is examined to reveal modifications of Dungey‐type magnetotail reconnection during sustained sub‐Alfvénic solar wind. The simulation shows new magnetospheric flux is generated via reconnection between polar cap field lines from the northern and southern hemisphere, similar to Dungey‐type magnetotail reconnection between lobe field lines mapping to opposite hemispheres. The key feature setting the Alfvén wing reconnection apart from the typical Dungey‐type is that the majority of new magnetospheric flux is added to the polar cap at local times 1–3 (21‐23) in the northern (southern) hemisphere. During most of the sub‐Alfvénic interval, reconnection mapping to midnight in the polar cap generates relatively little new magnetospheric flux.

Published
2024
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3. Chorus Wave Properties From Van Allen Probes: Quantifying the Impact of the Sheath Corrected Electric Field

Author

D. P. Hartley, I. W. Christopher, C. A. Kletzing, W. S. Kurth, O. Santolik, I. Kolmasova, M. R. Argall, and N. Ahmadi

Subjects
chorus waves, Van Allen Probes, radiation belt, electric field, sheath impedance, Geophysics. Cosmic physics, QC801-809
Abstract

Abstract A sheath impedance model has recently been developed to describe how the variable coupling impedance between the Van Allen Probes instrumentation and the ambient plasma affects both the amplitude and phase of electric field wave measurements. Here, the impact of this sheath correction on measured chorus wave properties, including electric field wave power and the Poynting vector, is directly quantified. It is found that the sheath‐corrected electric field wave power is typically between two and nine times larger than the uncorrected measurement, depending on wave frequency. The sheath correction typically increases the Poynting flux by a factor of ∼2, and causes the polar angle of the Poynting vector to switch hemisphere from parallel to anti‐parallel propagation in ∼2% of cases. The uncorrected data exhibit significant deviations from the theoretically predicted relationship between the wave vector and the Poynting vector whereas this relationship is well‐reproduced with the sheath‐corrected observations.

Published
2023
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8. Electron Inflow Velocities and Reconnection Rates at Earth's Magnetopause and Magnetosheath

Author

J. L. Burch, J. M. Webster, M. Hesse, K. J. Genestreti, R. E. Denton, T. D. Phan, H. Hasegawa, P. A. Cassak, R. B. Torbert, B. L. Giles, D. J. Gershman, R. E. Ergun, C. T. Russell, R. J. Strangeway, O. Le Contel, K. R. Pritchard, A. T. Marshall, K.‐J. Hwang, K. Dokgo, S. A. Fuselier, L.‐J. Chen, S. Wang, M. Swisdak, J. F. Drake, M. R. Argall, K. J. Trattner, M. Yamada, and G. Paschmann

Published
2020
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9. Effects in the Near‐Magnetopause Magnetosheath Elicited by Large‐Amplitude Alfvénic Fluctuations Terminating in a Field and Flow Discontinuity

Author

C. J. Farrugia, I. J. Cohen, B. J. Vasquez, N. Lugaz, L. Alm, R. B. Torbert, M. R. Argall, K. Paulson, B. Lavraud, D. J. Gershman, F. T. Gratton, H. Matsui, A. Rogers, T. G. Forbes, D. Payne, R. E. Ergun, B. Mauk, J. L. Burch, C. T. Russell, R. J. Strangeway, J. Shuster, R. Nakamura, S. A. Fuselier, B. L. Giles, Y. V. Khotyaintsev, P. A. Lindqvist, G.T. Marklund, S. M. Petrinec, and C. J. Pollock

Published
2018
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10. MMS, Van Allen Probes, GOES 13, and Ground‐Based Magnetometer Observations of EMIC Wave Events Before, During, and After a Modest Interplanetary Shock

Author

M. J. Engebretson, J. L. Posch, N. S. S. Capman, N. G. Campuzano, P. Bělik, R. C. Allen, S. K. Vines, B. J. Anderson, S. Tian, C. A. Cattell, J. R. Wygant, S. A. Fuselier, M. R. Argall, M. R. Lessard, R. B. Torbert, M. B. Moldwin, M. D. Hartinger, H. Kim, C. T. Russell, C. A. Kletzing, G. D. Reeves, and H. J. Singer

Published
2018
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13. Temporal, Spatial, and Velocity‐Space Variations of Electron Phase Space Density Measurements at the Magnetopause

Author

J. R. Shuster, D. J. Gershman, B. L. Giles, N. Bessho, A. S. Sharma, J. C. Dorelli, V. Uritsky, S. J. Schwartz, P. A. Cassak, R. E. Denton, L.‐J. Chen, H. Gurram, J. Ng, J. Burch, J. Webster, R. Torbert, W. R. Paterson, C. Schiff, A. F. Viñas, L. A. Avanov, J. Stawarz, T. C. Li, Y.‐H. Liu, M. R. Argall, A. Afshari, D. S. Payne, C. J. Farrugia, J. Verniero, F. Wilder, K. Genestreti, and D. E. da Silva

Subjects
Geophysics, Space and Planetary Science
Published
2023

14. MMS Observations of Reconnection at Dayside Magnetopause Crossings During Transitions of the Solar Wind to Sub‐Alfvénic Flow

Author

C. J. Farrugia, N. Lugaz, L. Alm, B. Vasquez, M. R. Argall, H. Kucharek, H. Matsui, R. B. Torbert, B. Lavraud, O. Le Contel, I. J. Cohen, J. L. Burch, C. T. Russell, R. J. Strangeway, J. Shuster, J. C. Dorelli, J. P. Eastwood, R. E. Ergun, S. A. Fuselier, D. J. Gershman, B. L. Giles, Y. V. Khotyaintsev, P. A. Lindqvist, G. T. Marklund, K. W. Paulson, S. M. Petrinec, T. D. Phan, and C. J. Pollock

Published
2017
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18. The Space Physics Environment Data Analysis System (SPEDAS)

Author

V. Angelopoulos, P. Cruce, A. Drozdov, E. W. Grimes, N. Hatzigeorgiu, D. A. King, D. Larson, J. W. Lewis, J. M. McTiernan, D. A. Roberts, C. L. Russell, T. Hori, Y. Kasahara, A. Kumamoto, A. Matsuoka, Y. Miyashita, Y. Miyoshi, I. Shinohara, M. Teramoto, J. B. Faden, A. J. Halford, M. McCarthy, R. M. Millan, J. G. Sample, D. M. Smith, L. A. Woodger, A. Masson, A. A. Narock, K. Asamura, T. F. Chang, C.-Y. Chiang, Y. Kazama, K. Keika, S. Matsuda, T. Segawa, K. Seki, M. Shoji, S. W. Y. Tam, N. Umemura, B.-J. Wang, S.-Y. Wang, R. Redmon, J. V. Rodriguez, H. J. Singer, J. Vandegriff, S. Abe, M. Nose, A. Shinbori, Y.-M. Tanaka, S. UeNo, L. Andersson, P. Dunn, C. Fowler, J. S. Halekas, T. Hara, Y. Harada, C. O. Lee, R. Lillis, D. L. Mitchell, M. R. Argall, K. Bromund, J. L. Burch, I. J. Cohen, M. Galloy, B. Giles, A. N. Jaynes, O. Le Contel, M. Oka, T. D. Phan, B. M. Walsh, J. Westlake, F. D. Wilder, S. D. Bale, R. Livi, M. Pulupa, P. Whittlesey, A. DeWolfe, B. Harter, E. Lucas, U. Auster, J. W. Bonnell, C. M. Cully, E. Donovan, R. E. Ergun, H. U. Frey, B. Jackel, A. Keiling, H. Korth, J. P. McFadden, Y. Nishimura, F. Plaschke, P. Robert, D. L. Turner, J. M. Weygand, R. M. Candey, R. C. Johnson, T. Kovalick, M. H. Liu, R. E. McGuire, A. Breneman, K. Kersten, and P. Schroeder

Published
2019
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19. Observations of whistler mode waves with nonlinear parallel electric fields near the dayside magnetic reconnection separatrix by the Magnetospheric Multiscale mission

Author

F. D. Wilder, R. E. Ergun, K. A. Goodrich, M. V. Goldman, D. L. Newman, D. M. Malaspina, A. N. Jaynes, S. J. Schwartz, K. J. Trattner, J. L. Burch, M. R. Argall, R. B. Torbert, P.‐A. Lindqvist, G. Marklund, O. Le Contel, L. Mirioni, Yu. V. Khotyaintsev, R. J. Strangeway, C. T. Russell, C. J. Pollock, B. L. Giles, F. Plaschke, W. Magnes, S. Eriksson, J. E. Stawarz, A. P. Sturner, and J. C. Holmes

Published
2016
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21. Ion‐scale secondary flux ropes generated by magnetopause reconnection as resolved by MMS

Author

J. P. Eastwood, T. D. Phan, P. A. Cassak, D. J. Gershman, C. Haggerty, K. Malakit, M. A. Shay, R. Mistry, M. Øieroset, C. T. Russell, J. A. Slavin, M. R. Argall, L. A. Avanov, J. L. Burch, L. J. Chen, J. C. Dorelli, R. E. Ergun, B. L. Giles, Y. Khotyaintsev, B. Lavraud, P. A. Lindqvist, T. E. Moore, R. Nakamura, W. Paterson, C. Pollock, R. J. Strangeway, R. B. Torbert, and S. Wang

Published
2016
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25. Millisecond observations of nonlinear wave–electron interaction in electron phase space holes

Author

C. Norgren, D. B. Graham, M. R. Argall, K. Steinvall, M. Hesse, Yu. V. Khotyaintsev, A. Vaivads, P. Tenfjord, D. J. Gershman, P.-A. Lindqvist, J. L. Burch, and F. Plaschke

Subjects
Fusion, plasma och rymdfysik, Astrophysics::High Energy Astrophysical Phenomena, Physics::Space Physics, Condensed Matter Physics, Fusion, Plasma and Space Physics
Abstract

Electron phase space holes (EHs) associated with electron trapping are commonly observed as bipolar electric field signatures in both space and laboratory plasma. Until recently, it has not been possible to resolve EHs in electron measurements. We report observations of EHs in the plasma sheet boundary layer, here identified as the separatrix region of magnetic reconnection in the magnetotail. The intense EHs are observed together with an electron beam moving toward the X line, showing signs of thermalization. Using the electron drift instrument onboard the satellites of the Magnetospheric Multiscale mission, we make direct millisecond measurements of the electron particle flux associated with individual electron phase space holes. The electron flux is measured at a millisecond cadence in a narrow parallel speed range within that of the trapped electrons. The flux modulations are of order unity and are direct evidence of the strong nonlinear wave-electron interaction that may effectively thermalize beams and contribute to transforming directed drift energy to thermal energy. (C) 2022 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

Published
2022

29. Transient, small-scale field-aligned currents in the plasma sheet boundary layer during storm time substorms

Author

R, Nakamura, V A, Sergeev, W, Baumjohann, F, Plaschke, W, Magnes, D, Fischer, A, Varsani, D, Schmid, T K M, Nakamura, C T, Russell, R J, Strangeway, H K, Leinweber, G, Le, K R, Bromund, C J, Pollock, B L, Giles, J C, Dorelli, D J, Gershman, W, Paterson, L A, Avanov, S A, Fuselier, K, Genestreti, J L, Burch, R B, Torbert, M, Chutter, M R, Argall, B J, Anderson, P-A, Lindqvist, G T, Marklund, Y V, Khotyaintsev, B H, Mauk, I J, Cohen, D N, Baker, A N, Jaynes, R E, Ergun, H J, Singer, J A, Slavin, E L, Kepko, T E, Moore, B, Lavraud, V, Coffey, and Y, Saito

Subjects
Ionosphere/Magnetosphere Interactions, Solar Physics, Astrophysics, and Astronomy, PSBL, electron beam, Field-Aligned Currents and Current Systems, First results from NASA's Magnetospheric Multiscale (MMS) Mission, Research Letters, MMS, Astronomi, astrofysik och kosmologi, Physics::Space Physics, Research Letter, Magnetotail Boundary Layers, Space Plasma Physics, Astronomy, Astrophysics and Cosmology, Meteorology & Atmospheric Sciences, Magnetospheric Physics, Magnetic Reconnection, Instruments and Techniques, Ionosphere, field‐aligned currents, Space Sciences, Current Systems, Magnetosphere/Ionosphere Interactions
Abstract

We report on field‐aligned current observations by the four Magnetospheric Multiscale (MMS) spacecraft near the plasma sheet boundary layer (PSBL) during two major substorms on 23 June 2015. Small‐scale field‐aligned currents were found embedded in fluctuating PSBL flux tubes near the separatrix region. We resolve, for the first time, short‐lived earthward (downward) intense field‐aligned current sheets with thicknesses of a few tens of kilometers, which are well below the ion scale, on flux tubes moving equatorward/earthward during outward plasma sheet expansion. They coincide with upward field‐aligned electron beams with energies of a few hundred eV. These electrons are most likely due to acceleration associated with a reconnection jet or high‐energy ion beam‐produced disturbances. The observations highlight coupling of multiscale processes in PSBL as a consequence of magnetotail reconnection., Key Points Multipoint multiscale observations of field‐aligned currents during storm time substormsSmall‐scale intense field‐aligned currents are found embedded in PSBL flux tubes near separatrix regionField‐aligned low‐energy electron beams correlate with short‐lived localized field‐aligned currents

Published
2016

30. New Insights into the Nature of Turbulence in the Earth's Magnetosheath Using Magnetospheric MultiScale Mission Data.

Author

H. Breuillard, L. Matteini, M. R. Argall, F. Sahraoui, M. Andriopoulou, O. Le Contel, A. Retinò, L. Mirioni, S. Y. Huang, D. J. Gershman, R. E. Ergun, F. D. Wilder, K. A. Goodrich, N. Ahmadi, E. Yordanova, A. Vaivads, D. L. Turner, Yu. V. Khotyaintsev, D. B. Graham, and P.-A. Lindqvist

Subjects
FLUCTUATIONS (Physics), TURBULENCE, ELECTROMAGNETISM, PLASMA heating, ENERGY dissipation
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. [ABSTRACT FROM AUTHOR]

Published
2018
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