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  • 101.
    Rosenqvist, Lisa
    et al.
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Opgenoorth, H. J.
    Rastaetter, L.
    Vaivads, Andris
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Dandouras, I.
    Buchert, Stephan
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Comparison of local energy conversion estimates from Cluster with global MHD simulations2008In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 35, no 21Article in journal (Refereed)
    Abstract [en]

    The local energy conversion across the magnetopause has been estimated with Cluster for two magnetopause crossings. A load region, conversion from magnetic to particle energy, was identified on the dayside high-latitude magnetopause during south/dawnward IMF. Another crossing of the dawn flank magnetotail during dominantly duskward IMF was identified as a generator region where the magnetosphere is loaded with magnetic energy. The observations have been compared to results of the BATS-R-US global MHD simulation based on observed IMF conditions. BATS-R-US reproduced the magnetopause regions crossed by Cluster as a load and a generator region, correspondingly. The magnitude of the estimated energy conversion from Cluster and the model are in quite good agreement. BATS-R-US cannot reproduce the observed sharp magnetopause and some topological differences between the observations and the model occur.

  • 102.
    Rosenqvist, Lisa
    et al.
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Vaivads, Andris
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Retinò, Alessandro
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Phan, T.
    Opgenoorth, H. J.
    Dandouras, I.
    Buchert, Stephan
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Modulated reconnection rate and energy conversion at the magnetopause under steady IMF conditions2008In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 35, no 8, article id L08104Article in journal (Refereed)
    Abstract [en]

    We use the multi-spacecraft mission Cluster to make observational estimates of the local energy conversion across the dayside high-latitude magnetopause. The energy conversion is estimated during eleven complete magnetopause crossings under steady south-dawnward interplanetary magnetic field (IMF). We describe a new method to determine the reconnection rate from the magnitude of the local energy conversion. The reconnection rate as well as the energy conversion varies during the course of the eleven crossings and is typically much higher for the outbound crossings. This supports the previous interpretation that reconnection is continuous but its rate is modulated.

  • 103. Runov, A.
    et al.
    Baumjohann, W.
    Nakamura, R.
    Sergeev, V. A.
    Amm, O.
    Frey, H.
    Alexeev, I.
    Fazakerley, A. N.
    Owen, C. J.
    Lucek, E.
    André, Mats
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Vaivads, Andris
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Dandouras, I.
    Klecker, B.
    Observations of an active thin current sheet2008In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 113, no A7, article id A07S27Article in journal (Refereed)
    Abstract [en]

    We analyze observations of magnetotail current sheet dynamics during a substorm between 2330 and 2400 UT on 28 August 2005 when Cluster was in the plasma sheet at [-17.2, -4.49, 0.03] R-E (GSM) with the foot points near the IMAGE ground-based network. Observations from the Cluster spacecraft, ground-based magnetometers, and the IMAGE satellite showed that the substorm started in a localized region near midnight, expanding azimuthally. A thin current sheet with a thickness of less than 900 km and current density of about 30 nA/m(2) was observed during 5 min around the substorm onset. The thinning of the current sheet was accompanied by tailward plasma flow at a velocity of -700 km/s and subsequent reversal to earthward flow at V-x approximate to 500 km/s coinciding with a B-z turning from -5 to + 10 nT. The analysis of magnetic and electric fields behavior and particle distributions reveals signatures of impulsive (with similar to 1 min timescale) activations of the thin current sheet. These observations were interpreted in the framework of transient reconnection, although the data analysis reveals serious disagreements with the classical 2.5-D X line model.

  • 104.
    Schwartz, Steven J.
    et al.
    Imperial Coll London, London, England;Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Avanov, Levon
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Turner, Drew
    Aerosp Corp, POB 92957, Los Angeles, CA 90009 USA.
    Zhang, Hui
    Univ Alaska Fairbanks, Geophys Inst, Fairbanks, AK 99775 USA.
    Gingell, Imogen
    Imperial Coll London, London, England.
    Eastwood, Jonathan P.
    Imperial Coll London, London, England.
    Gershman, Daniel J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Johlander, Andreas
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Russell, Christopher T.
    Univ Calif Los Angeles, Earth Planetary & Space Sci, Los Angeles, CA USA.
    Burch, James L.
    Southwest Res Inst, San Antonio, TX USA.
    Dorelli, John C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Eriksson, Stefan
    Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Ergun, Robert E.
    Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Fuselier, Stephen A.
    Southwest Res Inst, San Antonio, TX USA;Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX USA.
    Giles, Barbara L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Goodrich, Katherine A.
    Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Khotyaintsev, Yuri V.
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Lavraud, Benoit
    Imperial Coll London, London, England;Univ Toulouse, UPS, CNRS, Inst Rech Astrophys & Planetol,CNES, Toulouse, France.
    Lindqvist, Per-Arne
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Oka, Mitsuo
    Imperial Coll London, London, England;Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA.
    Phan, Tai-Duc
    Strangeway, Robert J.
    Univ Calif Los Angeles, Earth Planetary & Space Sci, Los Angeles, CA USA.
    Trattner, Karlheinz J.
    Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Torbert, Roy B.
    Imperial Coll London, London, England;Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.
    Vaivads, Andris
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Wei, Hanying
    Univ Calif Los Angeles, Earth Planetary & Space Sci, Los Angeles, CA USA.
    Wilder, Frederick
    Univ Colorado Boulder, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Ion Kinetics in a Hot Flow Anomaly: MMS Observations2018In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 45, no 21, p. 11520-11529Article in journal (Refereed)
    Abstract [en]

    Hot Flow Anomalies (HFAs) are transients observed at planetary bow shocks, formed by the shock interaction with a convected interplanetary current sheet. The primary interpretation relies on reflected ions channeled upstream along the current sheet. The short duration of HFAs has made direct observations of this process difficult. We employ high resolution measurements by NASA's Magnetospheric Multiscale Mission to probe the ion microphysics within a HFA. Magnetospheric Multiscale Mission data reveal a smoothly varying internal density and pressure, which increase toward the trailing edge of the HFA, sweeping up particles trapped within the current sheet. We find remnants of reflected or other backstreaming ions traveling along the current sheet, but most of these are not fast enough to out-run the incident current sheet convection. Despite the high level of internal turbulence, incident and backstreaming ions appear to couple gyro-kinetically in a coherent manner. Plain Language Summary Shock waves in space are responsible for energizing particles and diverting supersonic flows around planets and other obstacles. Explosive events known as Hot Flow Anomalies (HFAs) arise when a rapid change in the interplanetary magnetic field arrives at the bow shock formed by, for example, the supersonic solar wind plasma flow from the Sun impinging on the Earth's magnetic environment. HFAs are known to produce impacts all the way to ground level, but the physics responsible for their formation occur too rapidly to be resolved by previous satellite missions. This paper employs NASA's fleet of four Magnetospheric Multiscale satellites to reveal for the first time clear, discreet populations of ions that interact coherently to produce the extreme heating and deflection.

  • 105. Schwartz, Steven J.
    et al.
    Horbury, Timothy
    Owen, Christopher
    Baumjohann, Wolfgang
    Nakamura, Rumi
    Canu, Patrick
    Roux, Alain
    Sahraoui, Fouad
    Louarn, Philippe
    Sauvaud, Jean-Andre
    Pincon, Jean-Louis
    Vaivads, Andris
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Marcucci, Maria Federica
    Anastasiadis, Anastasios
    Fujimoto, Masaki
    Escoubet, Philippe
    Taylor, Matt
    Eckersley, Steven
    Allouis, Elie
    Perkinson, Marie-Claire
    Cross-scale: multi-scale coupling in space plasmas2009In: Experimental astronomy (Print), ISSN 0922-6435, E-ISSN 1572-9508, Vol. 23, no 3, p. 1001-1015Article in journal (Refereed)
    Abstract [en]

    Most of the visible universe is in the highly ionised plasma state, and most of that plasma is collision-free. Three physical phenomena are responsible for nearly all of the processes that accelerate particles, transport material and energy, and mediate flows in systems as diverse as radio galaxy jets and supernovae explosions through to solar flares and planetary magnetospheres. These processes in turn result from the coupling amongst phenomena at macroscopic fluid scales, smaller ion scales, and down to electron scales. Cross-Scale, in concert with its sister mission SCOPE (to be provided by the Japan Aerospace Exploration Agency-JAXA), is dedicated to quantifying that nonlinear, time-varying coupling via the simultaneous in-situ observations of space plasmas performed by a fleet of 12 spacecraft in near-Earth orbit. Cross-Scale has been selected for the Assessment Phase of Cosmic Vision by the European Space Agency.

  • 106.
    Soucek, J.
    et al.
    Acad Sci Czech Republic, Inst Atmospher Phys, Prague, Czech Republic..
    Åhlén, Lennart
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Bale, S.
    UCB, Space Sci Lab, Berkeley, CA USA..
    Bonnell, J.
    UCB, Space Sci Lab, Berkeley, CA USA..
    Boudin, N.
    ESA ESTEC, Noordwijk, Netherlands..
    Brienza, D.
    IAPS, Rome, Italy..
    Carr, C.
    Imperial Coll, London, England..
    Cipriani, F.
    ESA ESTEC, Noordwijk, Netherlands..
    Escoubet, C. P.
    ESA ESTEC, Noordwijk, Netherlands..
    Fazakerley, A.
    UCL, Mullard Space Sci Lab, Dorking, Surrey, England..
    Gehler, M.
    ESA ESTEC, Noordwijk, Netherlands..
    Genot, V.
    IRAP, Toulouse, France..
    Hilgers, A.
    ESA ESTEC, Noordwijk, Netherlands..
    Hanock, B.
    UCL, Mullard Space Sci Lab, Dorking, Surrey, England..
    Jannet, G.
    LPC2E, Orleans, France..
    Junge, A.
    ESA ESTEC, Noordwijk, Netherlands..
    Khotyaintsev, Yuri
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    De Keyser, J.
    BIRA IASB, Brussels, Belgium..
    Kucharek, H.
    Univ New Hampshire, Durham, NH 03824 USA..
    Lan, R.
    Acad Sci Czech Republic, Inst Atmospher Phys, Prague, Czech Republic..
    Lavraud, B.
    IRAP, Toulouse, France..
    Leblanc, F.
    Plasma Phys Lab, Paris, France..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Mansour, M.
    Plasma Phys Lab, Paris, France..
    Marcucci, M. F.
    IAPS, Rome, Italy..
    Nakamura, R.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Nemecek, Z.
    Charles Univ Prague, Prague, Czech Republic..
    Owen, C.
    UCL, Mullard Space Sci Lab, Dorking, Surrey, England..
    Phal, Y.
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Retino, A.
    Plasma Phys Lab, Paris, France..
    Rodgers, D.
    ESA ESTEC, Noordwijk, Netherlands..
    Safrankova, J.
    Charles Univ Prague, Prague, Czech Republic..
    Sahraoui, F.
    Plasma Phys Lab, Paris, France..
    Vainio, R.
    Univ Turku, Turku, Finland..
    Wimmer-Schweingruber, R.
    Univ Kiel, Kiel, Germany..
    Steinhagen, J.
    Univ Kiel, Kiel, Germany..
    Vaivads, Andris
    Uppsala universitet, Institutet för rymdfysik, Uppsalaavdelningen.
    Wielders, A.
    ESA ESTEC, Noordwijk, Netherlands..
    Zaslavsky, A.
    Observ Paris, LESIA, Ifeudon, France..
    EMC Aspects Of Turbulence Heating Observer (THOR) Spacecraft2016In: Proceedings Of 2016 Esa Workshop On Aerospace Emc (Aerospace Emc), 2016Conference paper (Refereed)
    Abstract [en]

    Turbulence Heating ObserveR (THOR) is a spacecraft mission dedicated to the study of plasma turbulence in near-Earth space. The mission is currently under study for implementation as a part of ESA Cosmic Vision program. THOR will involve a single spinning spacecraft equipped with state of the art instruments capable of sensitive measurements of electromagnetic fields and plasma particles. The sensitive electric and magnetic field measurements require that the spacecraft-generated emissions are restricted and strictly controlled; therefore a comprehensive EMC program has been put in place already during the study phase. The THOR study team and a dedicated EMC working group are formulating the mission EMC requirements already in the earliest phase of the project to avoid later delays and cost increases related to EMC. This article introduces the THOR mission and reviews the current state of its EMC requirements.

  • 107.
    Steinvall, K.
    et al.
    Swedish Inst Space Phys, Uppsala, Sweden.;Uppsala Univ, Dept Phys & Astron, Uppsala, Sweden..
    Khotyaintsev, Yu. V.
    Swedish Inst Space Phys, Uppsala, Sweden..
    Graham, D. B.
    Swedish Inst Space Phys, Uppsala, Sweden..
    Vaivads, Andris
    Swedish Inst Space Phys, Uppsala, Sweden..
    Lindqvist, Per-Arne
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics.
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA USA..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA..
    Multispacecraft Analysis of Electron Holes2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 1, p. 55-63Article in journal (Refereed)
    Abstract [en]

    Electron holes (EHs) are nonlinear electrostatic structures in plasmas. Most previous in situ studies of EHs have been limited to single- and two-spacecraft methods. We present statistics of EHs observed by Magnetospheric Multiscale on the magnetospheric side of the magnetopause during October 2016 when the spacecraft separation was around 6km. Each EH is observed by all four spacecraft, allowing EH properties to be determined with unprecedented accuracy. We find that the parallel length scale, l(vertical bar), scales with the Debye length. The EHs can be separated into three groups of speed and potential based on their coupling to ions. We present a method for calculating the perpendicular length scale, l. The method can be applied to a small subset of the observed EHs for which we find shapes ranging from almost spherical to more oblate. For the remaining EHs we use statistical arguments to find l/l(vertical bar)approximate to 5, implying dominance of oblate EHs. Plain Language Summary Electron holes are positively charged structures moving along the magnetic field and are frequently observed in space plasmas in relation to strong currents and electron beams. Electron holes interact with the plasma, leading to electron heating and scattering. In order to understand the effect of these electron holes, we need to accurately determine their properties, such as velocity, length scale, and potential. Most earlier studies have relied on single- or two-spacecraft methods to analyze electron holes. In this study we use the four satellites of the Magnetospheric Multiscale mission to analyze 236 electron holes with unprecedented accuracy. We find that the holes can be divided into three distinct groups with different properties. Additionally, we calculate the width of individual electron holes, finding that they are typically much wider than long, resembling pancakes.

  • 108. Stenberg, G.
    et al.
    Oscarsson, T.
    Andre, M.
    Vaivads, Andris
    Backrud-Ivgren, Marie
    KTH, School of Electrical Engineering (EES), Centres, Alfvén Laboratory Centre for Space and Fusion Plasma Physics.
    Khotyaintsev, Y.
    Rosenqvist, L.
    Sahraoui, F.
    Cornilleau-Wehrlin, N.
    Fazakerley, A.
    Lundin, R.
    Decreau, P. M. E.
    Internal structure and spatial dimensions of whistler wave regions in the magnetopause boundary layer2007In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 25, no 11, p. 2439-2451Article in journal (Refereed)
    Abstract [en]

    We use whistler waves observed close to the magnetopause as an instrument to investigate the internal structure of the magnetopause-magnetosheath boundary layer. We find that this region is characterized by tube-like structures with dimensions less than or comparable with an ion inertial length in the direction perpendicular to the ambient magnetic field. The tubes are revealed as they constitute regions where whistler waves are generated and propagate. We believe that the region containing tube-like structures extend several Earth radii along the magnetopause in the boundary layer. Within the presumed wave generating regions we find current structures moving at the whistler wave group velocity in the same direction as the waves.

123 101 - 108 of 108
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