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  • 51. Aunai, N.
    et al.
    Retino, A.
    Belmont, G.
    Smets, R.
    Lavraud, B.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    The proton pressure tensor as a new proxy of the proton decoupling region in collisionless magnetic reconnection2011In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 29, no 9, p. 1571-1579Article in journal (Refereed)
    Abstract [en]

    Cluster data is analyzed to test the proton pressure tensor variations as a proxy of the proton decoupling region in collisionless magnetic reconnection. The Hall electric potential well created in the proton decoupling region results in bounce trajectories of the protons which appears as a characteristic variation of one of the in-plane off-diagonal components of the proton pressure tensor in this region. The event studied in this paper is found to be consistent with classical Hall field signatures with a possible 20% guide field. Moreover, correlations between this pressure tensor component, magnetic field and bulk flow are proposed and validated, together with the expected counterstreaming proton distribution functions.

  • 52.
    Backrud, Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Tjulin, Anders
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Fazakerley, Andrew
    Interferometric Identification of Ion Acoustic Broadband Waves in the Auroral Region: CLUSTER Observations2005In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 32, no 21Article in journal (Refereed)
    Abstract [en]

    [1] We determine the phase velocity and k vector for parallel and oblique broadband extremely low frequency, ELF, waves on nightside auroral magnetic field lines at altitudes around 4.6 RE. We use internal burst mode data from the EFW electric field and wave instrument onboard the Cluster spacecraft to retrieve phase differences between the four probes of the instrument. The retrieved characteristic phase velocity is of the order of the ion acoustic speed and larger than the thermal velocity of the protons. The typical wavelength obtained from interferometry is around the proton gyro radius and always larger than the Debye length. We find that in regions with essentially no suprathermal electrons above a few tens of eV the observed broadband waves above the proton gyro frequency are consistent with upgoing ion acoustic and oblique ion acoustic waves.

  • 53.
    Backrud-Ivgren, Marie
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Astronomy and Space Physics.
    Stenberg, Gabriella
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Morooka, Michiko
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Hobara, Yasuhide
    Joko, Sachiko
    Rönnmark, Kjell
    Cornilleau-Wehrlin, Nicole
    Fazakerley, Andrew
    Rème, Henri
    Cluster observations and theoretical identification of broadband waves in the auroral region2005In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 23, no 12, p. 3739-3752Article in journal (Refereed)
    Abstract [en]

    Broadband waves are common on auroral field lines. We use two different methods to study the polarization of the waves at 10 to 180 Hz observed by the Cluster spacecraft at altitudes of about 4 Earth radii in the nightside auroral region. Observations of electric and magnetic wave fields, together with electron and ion data, are used as input to the methods. We find that much of the wave emissions are consistent with linear waves in homogeneous plasma. Observed waves with a large electric field perpendicular to the geomagnetic field are more common (electrostatic ion cyclotron waves), while ion acoustic waves with a large parallel electric field appear in smaller regions without suprathermal (tens of eV) plasma. The regions void of suprathermal plasma are interpreted as parallel potential drops of a few hundred volts.

  • 54.
    Bader, A.
    et al.
    Swedish Inst Space Phys, Kiruna, Sweden;Lulea Tekniska Univ, Kiruna, Sweden;Univ Lancaster, Phys, Lancaster, England.
    Wieser, G. Stenberg
    Swedish Inst Space Phys, Kiruna, Sweden.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Wieser, M.
    Swedish Inst Space Phys, Kiruna, Sweden.
    Futaana, Y.
    Swedish Inst Space Phys, Kiruna, Sweden.
    Persson, M.
    Swedish Inst Space Phys, Kiruna, Sweden;Umea Univ, Dept Phys, Umea, Sweden.
    Nilsson, H.
    Swedish Inst Space Phys, Kiruna, Sweden.
    Zhang, T. L.
    Austrian Acad Sci, Space Res Inst, Graz, Austria.
    Proton Temperature Anisotropies in the Plasma Environment of Venus2019In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 124, no 5, p. 3312-3330Article in journal (Refereed)
    Abstract [en]

    Velocity distribution functions (VDFs) are a key to understanding the interplay between particles and waves in a plasma. Any deviation from an isotropic Maxwellian distribution may be unstable and result in wave generation. Using data from the ion mass spectrometer IMA (Ion Mass Analyzer) and the magnetometer (MAG) onboard Venus Express, we study proton distributions in the plasma environment of Venus. We focus on the temperature anisotropy, that is, the ratio between the proton temperature perpendicular (T-perpendicular to) and parallel (T-parallel to) to the background magnetic field. We calculate average values of T-perpendicular to and T-parallel to for different spatial areas around Venus. In addition we present spatial maps of the average of the two temperatures and of their average ratio. Our results show that the proton distributions in the solar wind are quite isotropic, while at the bow shock stronger perpendicular than parallel heating makes the downstream VDFs slightly anisotropic (T-perpendicular to/T-parallel to > 1) and possibly unstable to generation of proton cyclotron waves or mirror mode waves. Both wave modes have previously been observed in Venus's magnetosheath. The perpendicular heating is strongest in the near-subsolar magnetosheath (T-perpendicular to/ T-parallel to approximate to 3/2), which is also where mirror mode waves are most frequently observed. We believe that the mirror mode waves observed here are indeed generated by the anisotropy. In the magnetotail we observe planetary protons with largely isotropic VDFs, originating from Venus's ionosphere.

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  • 55.
    Badman, S. V.
    et al.
    JAXA Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2525210, Japan..
    Andrews, David J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Cowley, S. W. H.
    Univ Leicester, Dept Phys & Astron, Leicester, Leics, England..
    Lamy, L.
    Observ Paris, Meudon, France..
    Provan, G.
    Univ Leicester, Dept Phys & Astron, Leicester, Leics, England..
    Tao, C.
    JAXA Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2525210, Japan..
    Kasahara, S.
    JAXA Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2525210, Japan..
    Kimura, T.
    JAXA Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2525210, Japan..
    Fujimoto, M.
    JAXA Inst Space & Astronaut Sci, Sagamihara, Kanagawa 2525210, Japan..
    Melin, H.
    Univ Leicester, Dept Phys & Astron, Leicester, Leics, England..
    Stallard, T.
    Univ Leicester, Dept Phys & Astron, Leicester, Leics, England..
    Brown, R. H.
    Univ Arizona, Lunar & Planetary Lab, Tucson, AZ USA..
    Baines, K. H.
    Univ Wisconsin Madison, SSEC, Madison, NJ USA..
    Rotational modulation and local time dependence of Saturn's infrared H-3(+) auroral intensity2012In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 117, article id A09228Article in journal (Refereed)
    Abstract [en]

    Planetary auroral emissions reveal the configuration of magnetospheric field-aligned current systems. In this study, Cassini Visual and Infrared Mapping Spectrometer (VIMS) observations of Saturn's pre-equinox infrared H-3(+) aurorae were analysed to show (a) rotational modulation of the auroral intensity in both hemispheres and (b) a significant local time dependence of the emitted intensity. The emission intensity is modulated by the 'planetary period' rotation of auroral current systems in each hemisphere. The northern auroral intensity also displays a lesser anti-phase dependence on the southern rotating current system, indicating that part of the southern current system closes in the northern hemisphere. The southern hemisphere aurorae were most intense in the post-dawn sector, in agreement with some past measurements of auroral field-aligned currents, UV aurora and SKR emitted power. A corresponding investigation of the northern hemisphere auroral intensity reveals a broader dawn-noon enhancement, possibly due to the interaction of the southern rotating current system with that of the north. The auroral intensity was reduced around dusk and post-midnight in both hemispheres. These observations can be explained by the interaction of a rotating field-aligned current system in each hemisphere with one fixed in local time, which is related to the solar wind interaction with magnetospheric field lines.

  • 56.
    Bale, S. D.
    et al.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA.;Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA..
    Goetz, K.
    Univ Minnesota, Sch Phys & Astron, Minneapolis, MN 55455 USA..
    Harvey, P. R.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Turin, P.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Bonnell, J. W.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Dudok de Wit, T.
    CNRS, LPC2E, 3A Ave Rech Sci, Orleans, France..
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO USA..
    MacDowall, R. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Pulupa, M.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Bolton, M.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO USA..
    Bougeret, J. -L
    Bowen, T. A.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA.;Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA..
    Burgess, D.
    Queen Mary Univ London, Astron Unit, London, England..
    Cattell, C. A.
    Univ Minnesota, Sch Phys & Astron, Minneapolis, MN 55455 USA..
    Chandran, B. D. G.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Chaston, C. C.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Chen, C. H. K.
    Imperial Coll, Dept Phys, London, England..
    Choi, M. K.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Connerney, J. E.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Cranmer, S.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO USA..
    Diaz-Aguado, M.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Donakowski, W.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Drake, J. F.
    Univ Maryland, Dept Phys, College Pk, MD 20742 USA..
    Farrell, W. M.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Fergeau, P.
    CNRS, LPC2E, 3A Ave Rech Sci, Orleans, France..
    Fermin, J.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Fischer, J.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Fox, N.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Glaser, D.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Goldstein, M.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Gordon, D.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Hanson, E.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA.;Univ Calif Berkeley, Dept Phys, Berkeley, CA 94720 USA..
    Harris, S. E.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Hayes, L. M.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Hinze, J. J.
    Univ Minnesota, Sch Phys & Astron, Minneapolis, MN 55455 USA..
    Hollweg, J. V.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Horbury, T. S.
    Imperial Coll, Dept Phys, London, England..
    Howard, R. A.
    Naval Res Lab, Washington, DC 20375 USA..
    Hoxie, V.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO USA..
    Jannet, G.
    CNRS, LPC2E, 3A Ave Rech Sci, Orleans, France..
    Karlsson, M.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO USA..
    Kasper, J. C.
    Univ Michigan, Ann Arbor, MI 48109 USA..
    Kellogg, P. J.
    Univ Minnesota, Sch Phys & Astron, Minneapolis, MN 55455 USA..
    Kien, M.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO USA..
    Klimchuk, J. A.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Krasnoselskikh, V. V.
    CNRS, LPC2E, 3A Ave Rech Sci, Orleans, France..
    Krucker, S.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Lynch, J. J.
    Univ Minnesota, Sch Phys & Astron, Minneapolis, MN 55455 USA..
    Maksimovic, M.
    Observ Paris, LESIA, Meudon, France..
    Malaspina, D. M.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO USA..
    Marker, S.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Martin, P.
    CNRS, LPC2E, 3A Ave Rech Sci, Orleans, France..
    Martinez-Oliveros, J.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    McCauley, J.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    McComas, D. J.
    Southwest Res Inst, San Antonio, TX USA..
    McDonald, T.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Meyer-Vernet, N.
    Observ Paris, LESIA, Meudon, France..
    Moncuquet, M.
    Observ Paris, LESIA, Meudon, France..
    Monson, S. J.
    Univ Minnesota, Sch Phys & Astron, Minneapolis, MN 55455 USA..
    Mozer, F. S.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Murphy, S. D.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Odom, J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Oliverson, R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Olson, J.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Parker, E. N.
    Univ Chicago, Dept Astron & Astrophys, 5640 S Ellis Ave, Chicago, IL 60637 USA..
    Pankow, D.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Phan, T.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Quataert, E.
    Univ Calif Berkeley, Dept Astron, 601 Campbell Hall, Berkeley, CA 94720 USA..
    Quinn, T.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Ruplin, S. W.
    Praxis Studios, Brooklyn, NY USA..
    Salem, C.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Seitz, D.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Sheppard, D. A.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Siy, A.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Stevens, K.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO USA..
    Summers, D.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO USA..
    Szabo, A.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Timofeeva, M.
    CNRS, LPC2E, 3A Ave Rech Sci, Orleans, France..
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Velli, M.
    UCLA, Earth Planetary & Space Sci, Los Angeles, CA USA..
    Yehle, A.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO USA..
    Werthimer, D.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Wygant, J. R.
    Univ Minnesota, Sch Phys & Astron, Minneapolis, MN 55455 USA..
    The FIELDS Instrument Suite for Solar Probe Plus2016In: Space Science Reviews, ISSN 0038-6308, E-ISSN 1572-9672, Vol. 204, no 1-4, p. 49-82Article, review/survey (Refereed)
    Abstract [en]

    NASA's Solar Probe Plus (SPP) mission will make the first in situ measurements of the solar corona and the birthplace of the solar wind. The FIELDS instrument suite on SPP will make direct measurements of electric and magnetic fields, the properties of in situ plasma waves, electron density and temperature profiles, and interplanetary radio emissions, amongst other things. Here, we describe the scientific objectives targeted by the SPP/FIELDS instrument, the instrument design itself, and the instrument concept of operations and planned data products.

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    fulltext
  • 57. Baumjohann, W.
    et al.
    Roux, A.
    Le Contel, O.
    Nakamura, R.
    Birn, J.
    Hoshino, M.
    Lui, A. T. Y.
    Owen, C. J.
    Sauvaud, J. -A
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Fontaine, D.
    Runov, A.
    Dynamics of thin current sheets: Cluster observations2007In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 25, no 6, p. 1365-1389Article, review/survey (Refereed)
    Abstract [en]

    The paper tries to sort out the specific signatures of the Near Earth Neutral Line (NENL) and the Current Disruption (CD) models. and looks for these signatures in Cluster data from two events. For both events transient magnetic si-natures are observed, together with fast ion flows. In the simplest form of NENL scenario, with a large-scale two-dimensional reconnection site, quasi-invariance along Y is expected. Thus the magnetic signatures in the S/C frame are interpreted as relative motions, along the X or Z direction, of a quasi-steady X-line, with respect to the S/C. In the simplest form of CD scenario an azimuthal modulation is expected. Hence the signatures in the S/C frame are interpreted as signatures of azimuthally (along Y) moving current system associated with low frequency fluctuations of J(y) and the corresponding field-aligned currents Event I covers a pseudo-breakup, developing only at high latitudes. First, a thin (H approximate to 2000Km approximate to 2 rho(i), with pi the ion gyroradius) Current Sheet (CS) is found to be quiet. A slightly thinner CS (H approximate to 1000-2000 km approximate to 1-2 rho(i)), crossed about 30 min later, is found to be active. with fast earthward ion flow bursts (300-600 km/s) and simultaneous large amplitude fluctuations (delta B/B similar to 1). In the quiet CS the current density J(y) is carried by ions. Conversely, in the active CS ions are moving eastward; the westward current is carried by electrons that move eastward, faster than ions. Similarly, the velocity of earthward flows (300-600 km/s), observed during the active period. maximizes near or at the CS center. During the active phase of Event I no signature of the crossing of an X-line is identified, but an X-line located beyond Cluster could account for the observed ion flows, provided that it is active for at least 20 min. Ion flow bursts can also be due to CD and to the corresponding dipolarizations which are associated with changes in the current density. Yet their durations are shorter than the duration of the active period. While the overall partial derivative Bz/partial derivative t is too weak to accelerate ions up to the observed velocities, short duration partial derivative B-z/partial derivative t can produce the azimuthal electric field requested to account for the observed ion flow bursts. The corresponding large amplitude perturbations are shown to move eastward. which suggests that the reduction in the tail current could be achieved via a series of eastward traveling partial dipolarisations/CD. The second event is much more active than the first one. The observed flapping of the CS corresponds to an azimuthally propagating wave. A reversal in the proton flow velocity, from 1000 to + 1000 km/s, is measured by CODIF. The overall flow reversal, the associated change in the sign of B-z and the relationship between B-x and B-y suggest that the spacecraft are moving with respect to an X-line and its associated Hall-structure. Yet, a simple tailward retreat of a large-scale X-line cannot account for all the observations, since several flow reversals are observed. These quasi-periodic flow reversals can also be associated with an azimuthal motion of the low frequency oscillations. Indeed, at the beginning of the interval B-y varies rapidly along the Y direction; the magnetic signature is three-dimensional and essentially corresponds to a structure of filamentary field-aligned current, moving eastward at similar to 200 km/s. The transverse size of the structure is similar to 1000 km. Similar structures are observed before and after. Thesefilamentary structures are consistent with an eastward propagation of an azimuthal modulation associated with a current system J(y), J(x). During Event 1, signatures of filamentary field-aligned current structures are also observed, in association with modulations of J(y). Hence, for both events the structure of the magnetic fields and currents is three-dimensional.

  • 58. Bavassano Cattaneo, M. Bice
    et al.
    Marcucci, M. Federica
    Retinò, Alessandro
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Pallocchia, G.
    Rème, H.
    Dandouras, I.
    Kistler, L. M.
    Klecker, B.
    Carlson, C. W.
    Korth, A.
    McCarthy, M.
    Lundin, Rickard
    Balogh, A.
    Kinetic signatures during a quasi-continuous lobe reconnection event: Cluster Ion Spectrometer (CIS) observations2006In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 111, no A9, p. A09212-Article in journal (Refereed)
    Abstract [en]

    On 3 December 2001 the Cluster spacecraft observed a long-lasting lobe reconnection event in the southern high-latitude dusk magnetopause (MP) tailward of the cusp, during a 4 hour interval of mainly northward interplanetary magnetic field ( IMF) and of sub-Alfvenic magnetosheath flow. Almost all the MP encounters have accelerated flows ( for which the Walen test has been successfully verified by Retino et al. ( 2005)) as well as a large number of secondary populations related to reconnection, that is, ions of magnetosheath or magnetospheric origin which cross the MP either way. The detailed analysis of the distribution functions shows that the reconnection site frequently moves relative to the spacecraft, but simultaneous measurements by two spacecraft on opposite sides of the reconnection site indicate that the spacecraft's distance from the X line is small, i.e., below 3200 km. The vicinity to the X line throughout the event is probably the reason why the distribution functions characteristics agree with theoretical expectations on both sides of the reconnection site throughout this long event. Moreover, the detailed analysis of the distribution functions shows evidence, during a few time intervals, of dual reconnection, i.e., of reconnection simultaneously going on also in the northern hemisphere.

  • 59.
    Bergman, Jan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Carozzi, Tobia D.
    Onsala Space Observ, S-43882 Onsala, Sweden.
    Robinson, David
    Psi Tran Ltd, 14 Kenton Ave, Sunbury On Thomas TW16 SAR, England.
    Schilling, Klaus
    ZfT, Magdalene Schoch Str 5, D-97074 Wurzburg, Germany.
    Stavrinidis, Constantinos
    IABG mbH, Einsteinstr 20, D-85521 Ottobrunn, Germany.
    DARTS - Distributed Aperture Radio Telescope in Space - First Starlight Explorer2018In: 2ND URSI ATLANTIC RADIO SCIENCE MEETING (AT-RASC), IEEE , 2018Conference paper (Refereed)
    Abstract [en]

    Several studies and proposals have been undertaken in recent years to design a low frequency space radio telescope. However, despite the strong science case for the opening up of a brand-new window on the Universe at a low radio frequency that is largely unexplored, mission proposals have been significantly challenged with the lack of flight proven technologies, to implement a space telescope using low cost small spacecraft formations. In recent years, the advent of CubeSat technologies, interplanetary missions and radio frequency inter-satellite link (ISL) technology, have improved to the point that developing a mission where a space radio telescope is formed using a constellation of small satellites is now viable, to bring unique science offerings.

  • 60. Berthomier, M.
    et al.
    Fazakerley, A. N.
    Forsyth, C.
    Pottelette, R.
    Alexandrova, O.
    Anastasiadis, A.
    Aruliah, A.
    Blelly, P. -L
    Briand, C.
    Bruno, R.
    Canu, P.
    Cecconi, B.
    Chust, T.
    Daglis, I.
    Davies, J.
    Dunlop, M.
    Fontaine, D.
    Genot, V.
    Gustavsson, B.
    Haerendel, G.
    Hamrin, M.
    Hapgood, M.
    Hess, S.
    Kataria, D.
    Kauristie, K.
    Kemble, S.
    Khotyaintsev, Yuri
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Koskinen, H.
    Lamy, L.
    Lanchester, B.
    Louarn, P.
    Lucek, E.
    Lundin, R.
    Maksimovic, M.
    Manninen, J.
    Marchaudon, A.
    Marghitu, O.
    Marklund, G.
    Milan, S.
    Moen, J.
    Mottez, F.
    Nilsson, H.
    Ostgaard, N.
    Owen, C. J.
    Parrot, M.
    Pedersen, A.
    Perry, C.
    Pincon, J. -L
    Pitout, F.
    Pulkkinen, T.
    Rae, I. J.
    Rezeau, L.
    Roux, A.
    Sandahl, I.
    Sandberg, I.
    Turunen, E.
    Vogt, J.
    Walsh, A.
    Watt, C. E. J.
    Wild, J. A.
    Yamauchi, M.
    Zarka, P.
    Zouganelis, I.
    Alfven: magnetosphere-ionosphere connection explorers2012In: Experimental astronomy (Print), ISSN 0922-6435, E-ISSN 1572-9508, Vol. 33, no 2-3, p. 445-489Article in journal (Refereed)
    Abstract [en]

    The aurorae are dynamic, luminous displays that grace the night skies of Earth's high latitude regions. The solar wind emanating from the Sun is their ultimate energy source, but the chain of plasma physical processes leading to auroral displays is complex. The special conditions at the interface between the solar wind-driven magnetosphere and the ionospheric environment at the top of Earth's atmosphere play a central role. In this Auroral Acceleration Region (AAR) persistent electric fields directed along the magnetic field accelerate magnetospheric electrons to the high energies needed to excite luminosity when they hit the atmosphere. The "ideal magnetohydrodynamics" description of space plasmas which is useful in much of the magnetosphere cannot be used to understand the AAR. The AAR has been studied by a small number of single spacecraft missions which revealed an environment rich in wave-particle interactions, plasma turbulence, and nonlinear acceleration processes, acting on a variety of spatio-temporal scales. The pioneering 4-spacecraft Cluster magnetospheric research mission is now fortuitously visiting the AAR, but its particle instruments are too slow to allow resolve many of the key plasma physics phenomena. The Alfv,n concept is designed specifically to take the next step in studying the aurora, by making the crucial high-time resolution, multi-scale measurements in the AAR, needed to address the key science questions of auroral plasma physics. The new knowledge that the mission will produce will find application in studies of the Sun, the processes that accelerate the solar wind and that produce aurora on other planets.

  • 61. Bertucci, C.
    et al.
    Achilleos, N.
    Dougherty, M. K.
    Modolo, R.
    Coates, A. J.
    Szego, K.
    Masters, A.
    Ma, Y.
    Neubauer, F. M.
    Garnier, P.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Wahlund, Jan Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Young, D. T.
    The magnetic memory of Titan's ionized atmosphere2008In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 321, no 5895, p. 1475-1478Article in journal (Refereed)
    Abstract [en]

    After 3 years and 31 close flybys of Titan by the Cassini Orbiter, Titan was finally observed in the shocked solar wind, outside of Saturn's magnetosphere. These observations revealed that Titan's flow- induced magnetosphere was populated by "fossil" fields originating from Saturn, to which the satellite was exposed before its excursion through the magnetopause. In addition, strong magnetic shear observed at the edge of Titan's induced magnetosphere suggests that reconnection may have been involved in the replacement of the fossil fields by the interplanetary magnetic field.

  • 62. Bertucci, C.
    et al.
    Hamilton, D. C.
    Kurth, W. S.
    Hospodarsky, G.
    Mitchell, D.
    Sergis, N.
    Edberg, Niklas J. T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Dougherty, M. K.
    Titan's interaction with the supersonic solar wind2015In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 42, no 2, p. 193-200Article in journal (Refereed)
    Abstract [en]

    After 9years in the Saturn system, the Cassini spacecraft finally observed Titan in the supersonic and super-Alfvenic solar wind. These unique observations reveal that Titan's interaction with the solar wind is in many ways similar to unmagnetized planets Mars and Venus and active comets in spite of the differences in the properties of the solar plasma in the outer solar system. In particular, Cassini detected a collisionless, supercritical bow shock and a well-defined induced magnetosphere filled with mass-loaded interplanetary magnetic field lines, which drape around Titan's ionosphere. Although the flyby altitude may not allow the detection of an ionopause, Cassini reports enhancements of plasma density compatible with plasma clouds or streamers in the flanks of its induced magnetosphere or due to an expansion of the induced magnetosphere. Because of the upstream conditions, these observations may be also relevant to other bodies in the outer solar system such as Pluto, where kinetic processes are expected to dominate.

  • 63. Bertucci, C.
    et al.
    Neubauer, F. M.
    Szego, K.
    Wahlund, Jan Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Coates, A. J.
    Dougherty, M. K.
    Young, D. T.
    Kurth, W. S.
    Structure of Titan's mid-range magnetic tail: Cassini magnetometer observations during the T9 flyby2007In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 34, no 24, p. L24S02-Article in journal (Refereed)
    Abstract [en]

    We analyze the magnetic structure of Titan's mid-range magnetic tail (5-6 Titan radii downstream from the moon) during Cassini's T9 flyby. Cassini magnetometer (MAG) measurements reveal a well-defined, induced magnetic tail consisting of two lobes and a distinct central current sheet. MAG observations also indicate that Saturn's background magnetic field is close to the moon's orbital plane and that the magnetospheric flow has a significant component in the Saturn-Titan direction. The analysis of MAG data in a coordinate system based on the orientation of the background magnetic field and an estimation of the incoming flow direction suggests that Titan's magnetic tail is extremely asymmetric. An important source of these asymmetries is the connection of the inbound tail lobe and the outbound tail lobe to the dayside and nightside hemispheres of Titan, respectively. Another source could be the perturbations generated by changes in the upstream conditions.

  • 64.
    Beth, A.
    et al.
    Imperial Coll London, Dept Phys, Prince Consort Rd, London SW7 2AZ, England..
    Altwegg, K.
    Univ Bern, Phys Inst, CH-3012 Bern, Switzerland..
    Balsiger, H.
    Univ Bern, Phys Inst, CH-3012 Bern, Switzerland..
    Berthelier, J. -J
    Calmonte, U.
    Univ Bern, Phys Inst, CH-3012 Bern, Switzerland..
    Combi, M. R.
    Univ Michigan, Dept Atmospher Ocean & Space Sci, 2455 Hayward, Ann Arbor, MI 48109 USA..
    De Keyser, J.
    Royal Belgian Inst Space Aeron, BIRA, IASB, Ringlaan 3, B-1180 Brussels, Belgium..
    Dhooghe, F.
    Royal Belgian Inst Space Aeron, BIRA, IASB, Ringlaan 3, B-1180 Brussels, Belgium..
    Fiethe, B.
    TU Braunschweig, Inst Comp & Network Engn IDA, Hans Sommer Str 66, D-38106 Braunschweig, Germany..
    Fuselier, S. A.
    Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX 78228 USA.;Southwest Res Inst San Antonio, San Antonio, TX 78228 USA..
    Galand, M.
    Imperial Coll London, Dept Phys, Prince Consort Rd, London SW7 2AZ, England..
    Gasc, S.
    Univ Bern, Phys Inst, CH-3012 Bern, Switzerland..
    Gombosi, T. I.
    Univ Michigan, Dept Atmospher Ocean & Space Sci, 2455 Hayward, Ann Arbor, MI 48109 USA..
    Hansen, K. C.
    Univ Michigan, Dept Atmospher Ocean & Space Sci, 2455 Hayward, Ann Arbor, MI 48109 USA..
    Hassig, M.
    Univ Bern, Phys Inst, CH-3012 Bern, Switzerland.;Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX 78228 USA..
    Heritier, K. L.
    Imperial Coll London, Dept Phys, Prince Consort Rd, London SW7 2AZ, England..
    Kopp, E.
    Univ Bern, Phys Inst, CH-3012 Bern, Switzerland..
    Le Roy, L.
    Univ Bern, Phys Inst, CH-3012 Bern, Switzerland..
    Mandt, K. E.
    Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX 78228 USA.;Southwest Res Inst San Antonio, San Antonio, TX 78228 USA..
    Peroy, S.
    Imperial Coll London, Dept Phys, Prince Consort Rd, London SW7 2AZ, England..
    Rubin, M.
    Univ Bern, Phys Inst, CH-3012 Bern, Switzerland..
    Semon, T.
    Univ Bern, Phys Inst, CH-3012 Bern, Switzerland..
    Tzou, C. -Y
    Vigren, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    First in situ detection of the cometary ammonium ion NH4+ (protonated ammonia NH3) in the coma of 67P/C-G near perihelion2016In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 462, p. S562-S572Article in journal (Refereed)
    Abstract [en]

    In this paper, we report the first in situ detection of the ammonium ion NH4+ at 67P/Churyumov-Gerasimenko (67P/C-G) in a cometary coma, using the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA)/Double Focusing Mass Spectrometer (DFMS). Unlike neutral and ion spectrometers onboard previous cometary missions, the ROSINA/DFMS spectrometer, when operated in ion mode, offers the capability to distinguish NH4+ from H2O+ in a cometary coma. We present here the ion data analysis of mass-to-charge ratios 18 and 19 at high spectral resolution and compare the results with an ionospheric model to put these results into context. The model confirms that the ammonium ion NH4+ is one of the most abundant ion species, as predicted, in the coma near perihelion.

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  • 65. Blagoveshchenskaya, N. F.
    et al.
    Borlsova, T. D.
    Kornienko, V. A.
    Leyser, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Rietveld, M. T.
    Thidé, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Artificial field-aligned irregularities in the nightside auroral ionosphere2006In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 38, no 11, p. 2503-2510Article in journal (Refereed)
    Abstract [en]

    Experimental results from two Tromso HF heating experiments in the nightside high latitudinal F region are examined. Bi-static scatter measurements of HF diagnostic signals were carried out on the London-Tromso-St. Petersburg and Pori-Tromso-St. Petersburg paths using a Doppler spectral method. The properties and behaviour of artificial field-aligned small-scale irregularities (striations) in the nightside high latitudinal F-region in course of the Tromso ionospheric modification experiments are studied. Experimental studies have been performed by the use of phased array I with a beamwidth of 6 degrees instead of 12-14 degrees in phased array 2, more often used in Tromso ionospheric modification experiments. The comparison between two experiments carried out in the same background geophysical conditions, shows the strongest striations in the field-aligned position of the heater beam. Possible explanation for this angular dependence is self-focusing of HF pump waves on striations causing the energy to be distributed asymmetrically. A principal question related to HF heating experiments is how is the disturbed auroral ionosphere modified. The results obtained on two paths simultaneously have shown that the strong heater-induced striations were observed along with natural ones. Velocities of heater-induced striations were quite different at different parts of the heated volume. It is suggested that the heater-induced striations can be grouped in two patches at different heights possibly due to the temperature-gradient-driven instability.

  • 66. Blagoveshchenskaya, N. F.
    et al.
    Kornienko, V. A.
    Borisova, T. D.
    Rietveld, M. T.
    Bösinger, T.
    Thidé, Bo
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Leyser, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Brekke, A.
    Heater-induced phenomena in a coupled ionosphere-magnetosphere system2006In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 38, no 11, p. 2495-2502Article in journal (Refereed)
    Abstract [en]

    Experimental results from HF pumping experiments in the nightside auroral E and F region are reported. The experiments were carried out by the use of the EISCAT HF heating facility located near Tromso, Norway, allowing HF pumping the ionosphere in a near magnetic field-aligned direction. We present experimental results from multi-instrument observations related to heater-induced phenomena in a coupled ionosphere-magnetosphere system. The following results have been observed on different occasions: a reverberation effect in scattered signals observed simultaneously on two diagnostic paths which is an indication of Alfven wave generation. This phenomenon was seen under specific disturbed background geophysical conditions, namely, a high electron density in the F region up to 8 MHz produced by soft electron precipitation from the magnetosphere along with low electron density in lower ionosphere; increased ionospheric electric fields; ion outflows from the ionosphere. On another occasion a magnetospheric response to heater turning on and off was found from magnetic pulsation observations over a frequency range up to 5 Hz (the upper frequency limit of the sensitive magnetometer at Kilpisjarvi, located near Tromso). The response manifests itself about 1 min after the heater is turned on and off. Other results have shown the modification of a natural auroral arc and local spiral-like formation. It is thought that a local heater-driven current system is formed. An interesting feature is the generation of the heater-induced ion outflows from the ionosphere. They are observed in night hours under both quiet and disturbed magnetic conditions.

  • 67.
    Blanc, M.
    et al.
    Univ Toulouse 3, CNRS, IRAP, F-31062 Toulouse, France..
    Andrews, David. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Coates, A. J.
    Univ Coll London, Mullard Space Sci Lab, Dorking RH5 6NT, Surrey, England..
    Hamilton, D. C.
    Univ Maryland, Dept Phys, College Pk, MD 20742 USA..
    Jackman, C. M.
    Univ Southampton, Sch Phys & Astron, Southampton SO17 1BJ, Hants, England..
    Jia, X.
    Univ Michigan, Dept Atmospher Ocean & Space Sci, Ann Arbor, MI 48109 USA..
    Kotova, A.
    Univ Toulouse 3, CNRS, IRAP, F-31062 Toulouse, France.;Max Planck Inst Solar Syst Res, Gottingen, Germany..
    Morooka, M.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Smith, H. T.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Westlake, J. H.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Saturn Plasma Sources and Associated Transport Processes2015In: Space Science Reviews, ISSN 0038-6308, E-ISSN 1572-9672, Vol. 192, no 1-4, p. 237-283Article, review/survey (Refereed)
    Abstract [en]

    This article reviews the different sources of plasma for Saturn's magnetosphere, as they are known essentially from the scientific results of the Cassini-Huygens mission to Saturn and Titan. At low and medium energies, the main plasma source is the cloud produced by the "geyser" activity of the small satellite Enceladus. Impact ionization of this cloud occurs to produce on the order of 100 kg/s of fresh plasma, a source which dominates all the other ones: Titan (which produces much less plasma than anticipated before the Cassini mission), the rings, the solar wind (a poorly known source due to the lack of quantitative knowledge of the degree of coupling between the solar wind and Saturn's magnetosphere), and the ionosphere. At higher energies, energetic particles are produced by energy diffusion and acceleration of lower energy plasma produced by the interchange instabilities induced by the rapid rotation of Saturn, and possibly, for the highest energy range, by contributions from the CRAND process acting inside Saturn's magnetosphere. Discussion of the transport and acceleration processes acting on these plasma sources shows the importance of rotation-induced radial transport and energization of the plasma, and also shows how much the unexpected planetary modulation of essentially all plasma parameters of Saturn's magnetosphere remains an unexplained mystery.

  • 68.
    Blanco-Cano, Xochitl
    et al.
    Univ Nacl Autonoma Mexico, Inst Geofis, Mexico City, DF, Mexico..
    Battarbee, Markus
    Univ Helsinki, Dept Phys, Helsinki, Finland..
    Turc, Lucile
    Univ Helsinki, Dept Phys, Helsinki, Finland..
    Dimmock, Andrew P.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Aalto Univ, Sch Elect Engn, Dept Elect & Nanoengn, Espoo, Finland..
    Kilpua, Emilia K. J.
    Univ Helsinki, Dept Phys, Helsinki, Finland..
    Hoilijoki, Sanni
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Ganse, Urs
    Univ Helsinki, Dept Phys, Helsinki, Finland..
    Sibeck, David G.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Cassak, Paul A.
    West Virginia Univ, Dept Phys & Astron, Morgantown, WV USA..
    Fear, Robert C.
    Univ Southampton, Dept Phys & Astron, Southampton, Hants, England..
    Jarvinen, Riku
    Aalto Univ, Sch Elect Engn, Dept Elect & Nanoengn, Espoo, Finland.;Finnish Meteorol Inst, Helsinki, Finland..
    Juusola, Liisa
    Univ Helsinki, Dept Phys, Helsinki, Finland.;Finnish Meteorol Inst, Helsinki, Finland..
    Pfau-Kempf, Yann
    Univ Helsinki, Dept Phys, Helsinki, Finland..
    Vainio, Rami
    Univ Turku, Dept Phys & Astron, Turku, Finland..
    Palmroth, Minna
    Univ Helsinki, Dept Phys, Helsinki, Finland.;Finnish Meteorol Inst, Helsinki, Finland..
    Cavitons and spontaneous hot flow anomalies in a hybrid-Vlasov global magnetospheric simulation2018In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 36, no 4, p. 1081-1097Article in journal (Refereed)
    Abstract [en]

    In this paper we present the first identification of foreshock cavitons and the formation of spontaneous hot flow anomalies (SHFAs) with the Vlasiator global magnetospheric hybrid-Vlasov simulation code. In agreement with previous studies we show that cavitons evolve into SHFAs. In the presented run, this occurs very near the bow shock. We report on SHFAs surviving the shock crossing into the down-stream region and show that the interaction of SHFAs with the bow shock can lead to the formation of a magnetosheath cavity, previously identified in observations and simulations. We report on the first identification of long-term local weakening and erosion of the bow shock, associated with a region of increased foreshock SHFA and caviton formation, and repeated shock crossings by them. We show that SHFAs are linked to an increase in suprathermal particle pitch-angle spreads. The realistic length scales in our simulation allow us to present a statistical study of global caviton and SHFA size distributions, and their comparable size distributions support the theory that SHFAs are formed from cavitons. Virtual spacecraft observations are shown to be in good agreement with observational studies.

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  • 69. Blomberg, L. G.
    et al.
    Matsumoto, H.
    Bougeret, J. -L
    Kojima, H.
    Yagitani, S.
    Cumnock, J. A.
    Eriksson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Marklund, G. T.
    Wahlund, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Bylander, L.
    Åhlén, Lennart
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Holtet, J. A.
    Ishisaka, K.
    Kallio, E.
    Kasaba, Y.
    Matsuoka, A.
    Moncuquet, M.
    Mursula, K.
    Omura, Y.
    Trotignon, J. G.
    MEFISTO - An electric field instrument for BepiColombo/MMO2006In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 38, no 4, p. 672-679Article in journal (Refereed)
    Abstract [en]

    MEFISTO, together with the companion instrument WPT, are planning the first-ever in situ measurements of the electric field in the magnetosphere of planet Mercury. The instruments have been selected by JAXA for inclusion in the BepiColombo/MMO payload, as part of the Plasma Wave Investigation coordinated by Kyoto University. The magnetosphere of Mercury was discovered by Mariner 10 in 1974 and will be studied further by Messenger starting in 2011. However, neither spacecraft did or will measure the electric field. Electric fields are crucial in the dynamics of a magnetosphere and for the energy and plasma transport between different regions within the magnetosphere as well as between the magnetosphere and the surrounding regions. The MEFISTO instrument will be capable of measuring electric fields from DC to 3 MHz, and will thus also allow diagnostics of waves at all frequencies of relevance to the Hermean magnetosphere. MEFISTO is a double-probe electric field instrument. The double-probe technique has strong heritage and is well proven on missions such as Viking, Polar, and Cluster. For BepiColombo, a newly developed deployment mechanism is planned which reduces the mass by a factor of about 5 compared to conventional mechanisms for 15 in long booms. We describe the basic characteristics of the instrument and briefly discuss the new developments made to tailor the instrument to flight in Mercury orbit.

  • 70. Blomberg, L.G.
    et al.
    Wahlund, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Electric fields in the Hermean environment2006In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 38, no 4, p. 627-631Article in journal (Refereed)
    Abstract [en]

    Returning to Mercury with the BepiColombo mission will provide a unique opportunity to obtain in situ information on the electric field in Mercury's magnetosphere. The electric field plays a crucial role for plasma transport in the magnetosphere, for transfer of energy between different parts of the system, and for propagation of information. Measuring the electric field, we will be able to better understand plasma motion and wave propagation in Mercury's magnetosphere. Together with knowledge of the magnetic field a better understanding will be derived of the magnetospheric current systems and their closure at or near the planetary surface. Further, insight into possible substorms at Mercury will be gained. We here focus on the expected amplitudes and frequencies of the electric fields concerned and the requirements for instrument capability that they pose.

  • 71. Bortnik, J.
    et al.
    Li, W.
    Thorne, R. M.
    Angelopoulos, V.
    Cully, Christopher
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Bonnell, J.
    Le Contel, O.
    Roux, A.
    An Observation Linking the Origin of Plasmaspheric Hiss to Discrete Chorus Emissions2009In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 324, no 5928, p. 775-778Article in journal (Refereed)
    Abstract [en]

    A long-standing problem in the field of space physics has been the origin of plasmaspheric hiss, a naturally occurring electromagnetic wave in the high-density plasmasphere (roughly within 20,000 kilometers of Earth) that is known to remove the high-energy Van Allen Belt electrons that pose a threat to satellites and astronauts. A recent theory tied the origin of plasmaspheric hiss to a seemingly different wave in the outer magnetosphere, but this theory was difficult to test because of a challenging set of observational requirements. Here we report on the experimental verification of the theory, made with a five-satellite NASA mission. This confirmation will allow modeling of plasmaspheric hiss and its effects on the high-energy radiation environment.

  • 72.
    Borälv, E.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Astronomy, Swedish Institute of Space Physics, Uppsala Division.
    Donovan, E.
    al., et
    Storm-time intense proton aurora and its relation to plasma sheet densityIn: Annales Geophysicae, ISSN 0092-7689Article in journal (Refereed)
  • 73.
    Borälv, E.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Eglitis, P.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Opgenoorth, H. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Donovan, E.
    Reeves, G.
    Stauning, P.
    The dawn and dusk electrojet response to substorm onset2000In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 18, no 9, p. 1097-1107Article in journal (Refereed)
    Abstract [en]

    We have investigated the time delay between substorm onset and related reactions in the dawn and dusk ionospheric electrojets, clearly separated from the nightside located substorm current wedge by several hours in MLT. We looked for substorm onsets occurring over Greenland, where the onset was identified by a LANL satellite and DMI magnetometers located on Greenland. With this setup the MARIA magnetometer network was located at dusk, monitoring the eastward electrojet, and the IMAGE chain at dawn, for the westward jet. In the first few minutes following substorm onset, sudden enhancements of the electrojets were identified by looking for rapid changes in magnetograms. These results show that the speed of information transfer between the region of onset and the dawn and dusk ionosphere is very high. A number of events where the reaction seemed to preceed the onset were explained by either unfavorable instrument locations, preventing proper onset timing, or by the inner magnetosphere's reaction to the Earthward fast flows from the near-Earth neutral line model. Case studies with ionospheric coherent (SuperDARN) and incoherent (EISCAT) radars have been performed to see whether a convection-induced electric field or enhanced conductivity is the main agent for the reactions in the electrojets. The results indicate an imposed electric field enhancement.

  • 74.
    Borälv, E.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Opgenoorth, H. J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Baker, J. B.
    Kauristie, K.
    Bosqued, J.-M.
    Dewhurst, J. P.
    Fazakerley, A.
    Owen, C. J.
    Slavin, J. A.
    Correlation between ground-based observations of substorm signatures and magnetotail dynamics2005In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 23, p. 997-1011Article in journal (Refereed)
    Abstract [en]

    We present a substorm event study combining Cluster and ground-based instrumentation. For this event ground-based magnetograms show a substorm onset and two separate substorm intensifications over Scandinavia, at the time located in the pre-midnight sector. During the substorm Cluster is located in the southern plasma sheet at a downtail distance of 18.5 Re. For all the substorm signatures seen on ground, corresponding plasma sheet drop-outs and re-entries of all or individual spacecraft of the Cluster constellation are observed. In general, plasma sheet drop-outs are assumed to be due to plasma sheet thinning/thickening and/or to magnetotail flapping. However, in the literature there has been some disagreement on both spatial and temporal characteristics of plasma sheet thinning and thickening during substorms. We therefore investigate the causes for the plasma sheet drop-outs for this event, which at first glance appears to show plasma sheet thinning at substorm onset, contradictory to the present standpoint in the literature.

  • 75.
    Borälv, E.
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Physics, Department of Physics and Astronomy, Swedish Institute of Space Physics, Uppsala Division.
    Rae, I. J.
    Opgenoorth, H. J.
    Donovan, E.
    Besser, V.
    Tung, Y.-K.
    The global ionospheric response to a southward IMF turningIn: Annales Geophysicae, ISSN 0992-7689Article in journal (Refereed)
  • 76.
    Borälv, Eva
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Substorm Features in the High-Latitude Ionosphere and Magnetosphere: Multi-Instrument Observations2003Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The space around Earth, confined in the terrestrial magnetosphere, is to some extent shielded from the Sun's solar wind plasma and magnetic field. During certain conditions, however, strong interaction can occur between the solar wind and the magnetosphere, resulting in magnetospheric activity of several forms, among which substorms and storms are the most prominent. A general framework for how these processes work have been outlayed through the history of research, however, there still remain questions to be answered. The most striking example regards the onset of substorms, where both the onset cause and location in the magnetosphere/ionosphere are still debated. These are clearly not easily solved problems, since a substorm is a global process, ideally requiring simultaneous measurements in the magnetotail and ionosphere. Investigated in this work are temporal and spatial scales for substorm and convection processes in the Earth's magnetosphere and ionosphere. This is performed by combining observations from a number of both ground-based and spacecraft-borne instruments. The observations indicate that the magnetotail's cross-section is involved to a larger spatial extent than previously considered in the substorm process. Furthermore, convection changes result in topological changes of the magnetosphere on a fast time scale. The results show that the magnetosphere is, on a global magnetospheric scale, highly dynamic during convection changes and ensuing substorms.

    List of papers
    1. The dawn and dusk electrojet response to substorm onset
    Open this publication in new window or tab >>The dawn and dusk electrojet response to substorm onset
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    2000 (English)In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 18, no 9, p. 1097-1107Article in journal (Refereed) Published
    Abstract [en]

    We have investigated the time delay between substorm onset and related reactions in the dawn and dusk ionospheric electrojets, clearly separated from the nightside located substorm current wedge by several hours in MLT. We looked for substorm onsets occurring over Greenland, where the onset was identified by a LANL satellite and DMI magnetometers located on Greenland. With this setup the MARIA magnetometer network was located at dusk, monitoring the eastward electrojet, and the IMAGE chain at dawn, for the westward jet. In the first few minutes following substorm onset, sudden enhancements of the electrojets were identified by looking for rapid changes in magnetograms. These results show that the speed of information transfer between the region of onset and the dawn and dusk ionosphere is very high. A number of events where the reaction seemed to preceed the onset were explained by either unfavorable instrument locations, preventing proper onset timing, or by the inner magnetosphere's reaction to the Earthward fast flows from the near-Earth neutral line model. Case studies with ionospheric coherent (SuperDARN) and incoherent (EISCAT) radars have been performed to see whether a convection-induced electric field or enhanced conductivity is the main agent for the reactions in the electrojets. The results indicate an imposed electric field enhancement.

    Keywords
    Polar ionosphere, Electric field, Magnetospheric substorm, Delay time, Auroral electrojet, Radar observation, Magnetometry, Satellite observation, Greenland, North America, America
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-90580 (URN)
    Available from: 2003-05-15 Created: 2003-05-15 Last updated: 2017-12-14Bibliographically approved
    2. Timing of substorm onset signatures on the ground and at geostationary orbit
    Open this publication in new window or tab >>Timing of substorm onset signatures on the ground and at geostationary orbit
    2002 (English)In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 29, no 12, p. 33(1)-33(4)Article in journal (Refereed) Published
    Abstract [en]

    In order to study the relative timing of substorm onset signatures on the ground and at geostationary orbit we have used data of simultaneous dispersionless electron and proton injections from the LANL satellite 1991-80, located slightly westward of Scandinavia. Out of 9 years of data we have identified a number of events during which such injections occurred close to local magnetic midnight. By careful inspection of ground-based magnetograms from the Scandinavian magnetometer network, IMAGE, we then identified the location and time of the formation of a substorm current wedge (SCW) during these events. 40 clear cases of geostationary injections, which were clearly associated with the formation of SCWs, were found. A statistical study of these events reveals that there is a clear time delay of the order of several minutes in the occurrence of the substorm injection with respect to the first indication of the SCW measured on the ground.

    Keywords
    Europe, Scandinavia, Statistical analysis, Ion injection, Magnetosphere, Magnetospheric substorm, Delay time, Magnetogram, Proton, Electron injection, Timing
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-90581 (URN)
    Available from: 2003-05-15 Created: 2003-05-15 Last updated: 2017-12-14Bibliographically approved
    3. The global ionospheric response to a southward IMF turning
    Open this publication in new window or tab >>The global ionospheric response to a southward IMF turning
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    In: Annales Geophysicae, ISSN 0992-7689Article in journal (Refereed) Submitted
    Identifiers
    urn:nbn:se:uu:diva-90582 (URN)
    Available from: 2003-05-15 Created: 2003-05-15Bibliographically approved
    4. Correlation between ground-based observations of substorm signatures and magnetotail dynamics
    Open this publication in new window or tab >>Correlation between ground-based observations of substorm signatures and magnetotail dynamics
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    2005 (English)In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 23, p. 997-1011Article in journal (Refereed) Published
    Abstract [en]

    We present a substorm event study combining Cluster and ground-based instrumentation. For this event ground-based magnetograms show a substorm onset and two separate substorm intensifications over Scandinavia, at the time located in the pre-midnight sector. During the substorm Cluster is located in the southern plasma sheet at a downtail distance of 18.5 Re. For all the substorm signatures seen on ground, corresponding plasma sheet drop-outs and re-entries of all or individual spacecraft of the Cluster constellation are observed. In general, plasma sheet drop-outs are assumed to be due to plasma sheet thinning/thickening and/or to magnetotail flapping. However, in the literature there has been some disagreement on both spatial and temporal characteristics of plasma sheet thinning and thickening during substorms. We therefore investigate the causes for the plasma sheet drop-outs for this event, which at first glance appears to show plasma sheet thinning at substorm onset, contradictory to the present standpoint in the literature.

    Keywords
    Magnetospheric configuration and dynamics, Magnetotail, Plasma sheet, Storms and substorms
    National Category
    Physical Sciences
    Identifiers
    urn:nbn:se:uu:diva-90583 (URN)
    Available from: 2003-05-15 Created: 2003-05-15 Last updated: 2017-12-14Bibliographically approved
    5. Storm-time intense proton aurora and its relation to plasma sheet density
    Open this publication in new window or tab >>Storm-time intense proton aurora and its relation to plasma sheet density
    In: Annales Geophysicae, ISSN 0092-7689Article in journal (Refereed) Submitted
    Identifiers
    urn:nbn:se:uu:diva-90584 (URN)
    Available from: 2003-05-15 Created: 2003-05-15Bibliographically approved
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    FULLTEXT01
  • 77. Brain, D.
    et al.
    Barabash, S.
    Boesswetter, A.
    Bougher, S.
    Brecht, S.
    Chanteur, G.
    Hurley, D.
    Dubinin, E.
    Fang, X.
    Fraenz, M.
    Halekas, J.
    Harnett, E.
    Holmström, M.
    Kallio, E.
    Lammer, H.
    Ledvina, S.
    Liemohn, M.
    Liu, K.
    Luhmann, J.
    Ma, Y.
    Modolo, Ronan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Nagy, A.
    Motschmann, U.
    Nilsson, H.
    Shinagawa, H.
    Simon, S.
    Terada, N.
    A comparison of global models for the solar wind interaction with Mars2010In: Icarus (New York, N.Y. 1962), ISSN 0019-1035, E-ISSN 1090-2643, Vol. 206, no 1, p. 139-151Article in journal (Refereed)
    Abstract [en]

    We present initial results from the first community-wide effort to compare global plasma interaction model results for Mars. Seven modeling groups participated in this activity, using MHD, multi-fluid, and hybrid assumptions in their simulations. Moderate solar wind and solar EUV conditions were chosen, and the conditions were implemented in the models and run to steady state. Model output was compared in three ways to determine how pressure was partitioned and conserved in each model, the location and asymmetry of plasma boundaries and pathways for planetary ion escape, and the total escape flux of planetary oxygen ions. The two participating MHD models provided similar results, while the five sets of multi-fluid and hybrid results were different in many ways. All hybrid results, however, showed two main channels for oxygen ion escape (a pickup ion 'plume' in the hemisphere toward which the solar wind convection electric field is directed, and a channel in the opposite hemisphere of the central magnetotail), while the MHD models showed one (a roughly symmetric channel in the central magnetotail). Most models showed a transition from an upstream region dominated by plasma dynamic pressure to a magnetosheath region dominated by thermal pressure to a low altitude region dominated by magnetic pressure. However, calculated escape rates for a single ion species varied by roughly an order of magnitude for similar input conditions, suggesting that the uncertainties in both the current and integrated escape over martian history as determined by models are large. These uncertainties are in addition to those associated with the evolution of the Sun, the martian dynamo, and the early atmosphere, highlighting the challenges we face in constructing Mars' past using models.

  • 78.
    Breuillard, H.
    et al.
    Univ Orleans, CNES, CNRS, UMR7328,LPC2E, Orleans, France;Univ Paris Sud, Sorbonne Univ, Ecole Polytech, UMR7648 CNRS,Lab Phys Plasmas, Paris, France.
    Henri, P.
    Univ Orleans, CNES, CNRS, UMR7328,LPC2E, Orleans, France.
    Bucciantini, L.
    Univ Orleans, CNES, CNRS, UMR7328,LPC2E, Orleans, France.
    Volwerk, M.
    Austrian Acad Sci, Space Res Inst, Graz, Austria.
    Karlsson, T.
    KTH Royal Inst Technol, Stockholm, Sweden.
    Eriksson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Johansson, Fredrik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Odelstad, E.
    Swedish Inst Space Phys, Uppsala, Sweden.
    Richter, I
    Tech Univ Carolo Wilhelmina Braunschweig, Braunschweig, Germany.
    Goetz, C.
    Tech Univ Carolo Wilhelmina Braunschweig, Braunschweig, Germany.
    Vallieres, X.
    Univ Orleans, CNES, CNRS, UMR7328,LPC2E, Orleans, France.
    Hajra, R.
    Univ Orleans, CNES, CNRS, UMR7328,LPC2E, Orleans, France;Natl Atmospher Res Lab, Tirupati, Andhra Pradesh, India.
    Properties of the singing comet waves in the 67P/Churyumov-Gerasimenko plasma environment as observed by the Rosetta mission2019In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 630, article id A39Article in journal (Refereed)
    Abstract [en]

    Using in situ measurements from different instruments on board the Rosetta spacecraft, we investigate the properties of the newly discovered low-frequency oscillations, known as singing comet waves, that sometimes dominate the close plasma environment of comet 67P/Churyumov-Gerasimenko. These waves are thought to be generated by a modified ion-Weibel instability that grows due to a beam of water ions created by water molecules that outgass from the comet. We take advantage of a cometary outburst event that occurred on 2016 February 19 to probe this generation mechanism. We analyze the 3D magnetic field waveforms to infer the properties of the magnetic oscillations of the cometary ion waves. They are observed in the typical frequency range (similar to 50 mHz) before the cometary outburst, but at similar to 20 mHz during the outburst. They are also observed to be elliptically right-hand polarized and to propagate rather closely (similar to 0-50 degrees) to the background magnetic field. We also construct a density dataset with a high enough time resolution that allows us to study the plasma contribution to the ion cometary waves. The correlation between plasma and magnetic field variations associated with the waves indicates that they are mostly in phase before and during the outburst, which means that they are compressional waves. We therefore show that the measurements from multiple instruments are consistent with the modified ion-Weibel instability as the source of the singing comet wave activity. We also argue that the observed frequency of the singing comet waves could be a way to indirectly probe the strength of neutral plasma coupling in the 67P environment.

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    FULLTEXT01
  • 79.
    Breuillard, H.
    et al.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Observ Paris, Paris, France..
    Le Contel, O.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Observ Paris, Paris, France..
    Chust, T.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Observ Paris, Paris, France..
    Berthomier, M.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Observ Paris, Paris, France..
    Retino, A.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Observ Paris, Paris, France..
    Turner, D. L.
    Aerosp Corp, Space Sci Dept, El Segundo, CA 90245 USA..
    Nakamura, R.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Baumjohann, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Cozzani, G.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Observ Paris, Paris, France..
    Catapano, F.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Observ Paris, Paris, France..
    Alexandrova, A.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Observ Paris, Paris, France..
    Mirioni, L.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Observ Paris, Paris, France..
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Argall, M. R.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Fischer, D.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Wilder, F. D.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Varsani, A.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Lindqvist, P. -A
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Marklund, G.
    Royal Inst Technol, Stockholm, Sweden..
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Goodrich, K. A.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Ahmadi, N.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA..
    Torbert, R. B.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Needell, G.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Chutter, M.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Rau, D.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Dors, I.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.;Univ New Hampshire, Space Sci Ctr, Durham, NH 03824 USA..
    Russell, C. T.
    Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Strangeway, R. J.
    Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA..
    Bromund, K. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Wei, H.
    Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA..
    Plaschke, F.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Anderson, B. J.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Le, G.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Moore, T. E.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Paterson, W. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Pollock, C. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Avanov, L. A.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Saito, Y.
    Inst Space & Astronaut Sci, Sagamihara, Kanagawa, Japan..
    Lavraud, B.
    Univ Paul Sabatier, CNRS UMR5277, Inst Rech Astrophys & Planetol, Toulouse, France..
    Fuselier, S. A.
    Southwest Res Inst, San Antonio, TX USA..
    Mauk, B. H.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Cohen, I. J.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Fennell, J. F.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Observ Paris, Paris, France..
    The Properties of Lion Roars and Electron Dynamics in Mirror Mode Waves Observed by the Magnetospheric MultiScale Mission2018In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 123, no 1, p. 93-103Article in journal (Refereed)
    Abstract [en]

    Mirror mode waves are ubiquitous in the Earth's magnetosheath, in particular behind the quasi‐perpendicular shock. Embedded in these nonlinear structures, intense lion roars are often observed. Lion roars are characterized by whistler wave packets at a frequency ∼100 Hz, which are thought to be generated in the magnetic field minima. In this study, we make use of the high time resolution instruments on board the Magnetospheric MultiScale mission to investigate these waves and the associated electron dynamics in the quasi‐perpendicular magnetosheath on 22 January 2016. We show that despite a core electron parallel anisotropy, lion roars can be generated locally in the range 0.05–0.2fce by the perpendicular anisotropy of electrons in a particular energy range. We also show that intense lion roars can be observed up to higher frequencies due to the sharp nonlinear peaks of the signal, which appear as sharp spikes in the dynamic spectra. As a result, a high sampling rate is needed to estimate correctly their amplitude, and the latter might have been underestimated in previous studies using lower time resolution instruments. We also present for the first‐time 3‐D high time resolution electron velocity distribution functions in mirror modes. We demonstrate that the dynamics of electrons trapped in the mirror mode structures are consistent with the Kivelson and Southwood (1996) model. However, these electrons can also interact with the embedded lion roars: first signatures of electron quasi‐linear pitch angle diffusion and possible signatures of nonlinear interaction with high‐amplitude wave packets are presented. These processes can lead to electron untrapping from mirror modes.

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  • 80.
    Breuillard, H.
    et al.
    CNRS, LPP, UMR, Paris, France..
    Le Contel, O.
    CNRS, LPP, UMR, Paris, France..
    Retino, A.
    CNRS, LPP, UMR, Paris, France..
    Chasapis, A.
    Univ Delaware, Dept Phys & Astron, Newark, DE 19716 USA..
    Chust, T.
    CNRS, LPP, UMR, Paris, France..
    Mirioni, L.
    CNRS, LPP, UMR, Paris, France..
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Wilder, F. D.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Cohen, I.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Lindqvist, P. -A
    Royal Inst Technol, Alfven Lab, Stockholm, Sweden.
    Marklund, G. T.
    Royal Inst Technol, Alfven Lab, Stockholm, Sweden..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA..
    Torbert, R. B.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA.;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Ergun, R. E.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Goodrich, K. A.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Macri, J.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA.;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Needell, J.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA.;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Chutter, M.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA.;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Rau, D.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA.;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Dors, I.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA.;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Russell, C. T.
    Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst IWF, Graz, Austria..
    Strangeway, R. J.
    Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA..
    Bromund, K. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Plaschke, F.
    Austrian Acad Sci, Space Res Inst IWF, Graz, Austria..
    Fischer, D.
    Austrian Acad Sci, Space Res Inst IWF, Graz, Austria..
    Leinweber, H. K.
    Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA..
    Anderson, B. J.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Le, G.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Slavin, J. A.
    Univ Michigan, Dept Climate & Space Sci & Engn, Ann Arbor, MI 48109 USA..
    Kepko, E. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Baumjohann, W.
    Austrian Acad Sci, Space Res Inst IWF, Graz, Austria..
    Mauk, B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Fuselier, S. A.
    Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX USA..
    Nakamura, R.
    Austrian Acad Sci, Space Res Inst IWF, Graz, Austria..
    Multispacecraft analysis of dipolarization fronts and associated whistler wave emissions using MMS data2016In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, no 14, p. 7279-7286Article in journal (Refereed)
    Abstract [en]

    Dipolarization fronts (DFs), embedded in bursty bulk flows, play a crucial role in Earth's plasma sheet dynamics because the energy input from the solar wind is partly dissipated in their vicinity. This dissipation is in the form of strong low-frequency waves that can heat and accelerate energetic electrons up to the high-latitude plasma sheet. However, the dynamics of DF propagation and associated low-frequency waves in the magnetotail are still under debate due to instrumental limitations and spacecraft separation distances. In May 2015 the Magnetospheric Multiscale (MMS) mission was in a string-of-pearls configuration with an average intersatellite distance of 160km, which allows us to study in detail the microphysics of DFs. Thus, in this letter we employ MMS data to investigate the properties of dipolarization fronts propagating earthward and associated whistler mode wave emissions. We show that the spatial dynamics of DFs are below the ion gyroradius scale in this region (approximate to 500km), which can modify the dynamics of ions in the vicinity of the DF (e.g., making their motion nonadiabatic). We also show that whistler wave dynamics have a temporal scale of the order of the ion gyroperiod (a few seconds), indicating that the perpendicular temperature anisotropy can vary on such time scales.

  • 81.
    Breuillard, H.
    et al.
    Univ Paris Sud, Sorbonne Univ, Ecole Polytech, Lab Phys Plasmas,UMR7648,CNRS, Paris, France.
    Matteini, L.
    UPMC Univ Paris 06, Univ Paris Diderot, PSL Res Univ, LESIA Observ Paris,CNRS, Meudon, France.
    Argall, M. R.
    Univ New Hampshire, Durham, NH 03824 USA.
    Sahraoui, F.
    Univ Paris Sud, Sorbonne Univ, Ecole Polytech, Lab Phys Plasmas,UMR7648,CNRS, Paris, France.
    Andriopoulou, M.
    Austrian Acad Sci, Space Res Inst, Graz, Austria.
    Le Contel, O.
    Univ Paris Sud, Sorbonne Univ, Ecole Polytech, Lab Phys Plasmas,UMR7648,CNRS, Paris, France.
    Retino, A.
    Univ Paris Sud, Sorbonne Univ, Ecole Polytech, Lab Phys Plasmas,UMR7648,CNRS, Paris, France.
    Mirioni, L.
    Univ Paris Sud, Sorbonne Univ, Ecole Polytech, Lab Phys Plasmas,UMR7648,CNRS, Paris, France.
    Huang, S. Y.
    Wuhan Univ, Sch Elect & Informat, Beijing, Peoples R China.
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Wilder, F. D.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Goodrich, K. A.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Ahmadi, N.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Yordanova, Emiliya
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Turner, D. L.
    Aerosp Corp, Space Sci Dept, El Segundo, CA 90245 USA.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Lindqvist, P. -A
    Chasapis, A.
    Univ Delaware, Newark, DE USA.
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA.
    Torbert, R. B.
    Univ New Hampshire, Durham, NH 03824 USA.
    Russell, C. T.
    Univ Calif Los Angeles, Los Angeles, CA USA.
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria.
    Strangeway, R. J.
    Plaschke, F.
    Austrian Acad Sci, Space Res Inst, Graz, Austria.
    Moore, T. E.
    Giles, B. L.
    Paterson, W. R.
    Pollock, C. J.
    Lavraud, B.
    Univ Paul Sabatier, CNRS UMR5277, IRAP, Toulouse, France.
    Fuselier, S. A.
    Southwest Res Inst, San Antonio, TX USA.
    Cohen, I. J.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA.
    New Insights into the Nature of Turbulence in the Earth's Magnetosheath Using Magnetospheric MultiScale Mission Data2018In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 859, no 2, article id 127Article in journal (Refereed)
    Abstract [en]

    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 > 1Hz) 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.

  • 82.
    Breuillard, H.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Yordanova, Emiliya
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Alexandrova, O.
    LESIA Observ Paris Meudon, Meudon, France..
    The Effects Of Kinetic Instabilities On Small-Scale Turbulence In Earth's Magnetosheath2016In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 829, no 1, article id 54Article in journal (Refereed)
    Abstract [en]

    The Earth's magnetosheath is the region delimited by the bow shock and the magnetopause. It is characterized by highly turbulent fluctuations covering all scales from MHD down to kinetic scales. Turbulence is thought to play a fundamental role in key processes such as energy transport and dissipation in plasma. In addition to turbulence, different plasma instabilities are generated in the magnetosheath because of the large anisotropies in plasma temperature introduced by its boundaries. In this study we use high-quality magnetic field measurements from Cluster spacecraft to investigate the effects of such instabilities on the small-scale turbulence (from ion down to electron scales). We show that the steepening of the power spectrum of magnetic field fluctuations in the magnetosheath occurs at the largest characteristic ion scale. However, the spectrum can be modified by the presence of waves/structures at ion scales, shifting the onset of the small-scale turbulent cascade toward the smallest ion scale. This cascade is therefore highly dependent on the presence of kinetic instabilities, waves, and local plasma parameters. Here we show that in the absence of strong waves the small-scale turbulence is quasi-isotropic and has a spectral index alpha approximate to 2.8. When transverse or compressive waves are present, we observe an anisotropy in the magnetic field components and a decrease in the absolute value of alpha. Slab/2D turbulence also develops in the presence of transverse/compressive waves, resulting in gyrotropy/non-gyrotropy of small-scale fluctuations. The presence of both types of waves reduces the anisotropy in the amplitude of fluctuations in the small-scale range.

  • 83.
    Broiles, Thomas W.
    et al.
    Southwest Res Inst, Div Space Sci & Engn, 6220 Culebra Rd, San Antonio, TX 78238 USA..
    Burch, J. L.
    Southwest Res Inst, Div Space Sci & Engn, 6220 Culebra Rd, San Antonio, TX 78238 USA..
    Chae, K.
    Southwest Res Inst, Div Space Sci & Engn, 6220 Culebra Rd, San Antonio, TX 78238 USA..
    Clark, G.
    Johns Hopkins Univ, Appl Phys Lab, 11100 Johns Hopkins Rd, Laurel, MD 20723 USA..
    Cravens, T. E.
    Univ Kansas, Dept Phys & Astron, 1450 Jayhawk Blvd, Lawrence, KS 66045 USA..
    Eriksson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Fuselier, S. A.
    Southwest Res Inst, Div Space Sci & Engn, 6220 Culebra Rd, San Antonio, TX 78238 USA.;Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX 78249 USA..
    Frahm, R. A.
    Southwest Res Inst, Div Space Sci & Engn, 6220 Culebra Rd, San Antonio, TX 78238 USA..
    Gasc, S.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Goldstein, R.
    Southwest Res Inst, Div Space Sci & Engn, 6220 Culebra Rd, San Antonio, TX 78238 USA..
    Henri, P.
    CNRS, LPC2E, F-45071 Orleans, France..
    Koenders, C.
    Tech Univ Carolo Wilhelmina Braunschweig, Inst Geophys & Extraterr Phys, Mendelssohnstr 3, D-38106 Braunschweig, Germany..
    Livadiotis, G.
    Southwest Res Inst, Div Space Sci & Engn, 6220 Culebra Rd, San Antonio, TX 78238 USA..
    Mandt, K. E.
    Southwest Res Inst, Div Space Sci & Engn, 6220 Culebra Rd, San Antonio, TX 78238 USA.;Univ Texas San Antonio, Dept Phys & Astron, San Antonio, TX 78249 USA..
    Mokashi, P.
    Southwest Res Inst, Div Space Sci & Engn, 6220 Culebra Rd, San Antonio, TX 78238 USA..
    Nemeth, Z.
    Wigner Res Ctr Phys, H-1121 Budapest, Hungary..
    Odelstad, Elias
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Space Plasma Physics. Univ Kansas, Dept Phys & Astron, 1450 Jayhawk Blvd, Lawrence, KS 66045 USA..
    Rubin, M.
    Univ Bern, Phys Inst, Sidlerstr 5, CH-3012 Bern, Switzerland..
    Samara, M.
    Goddard Space Flight Ctr, Heliophys Div, 8800 Greenbelt Rd, Greenbelt, MD 20771 USA..
    Statistical analysis of suprathermal electron drivers at 67P/Churyumov-Gerasimenko2016In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 462, p. S312-S322Article in journal (Refereed)
    Abstract [en]

    We use observations from the Ion and Electron Sensor (IES) on board the Rosetta spacecraft to study the relationship between the cometary suprathermal electrons and the drivers that affect their density and temperature. We fit the IES electron observations with the summation of two kappa distributions, which we characterize as a dense and warm population (similar to 10 cm(-3) and similar to 16 eV) and a rarefied and hot population (similar to 0.01 cm(-3) and similar to 43 eV). The parameters of our fitting technique determine the populations' density, temperature, and invariant kappa index. We focus our analysis on the warm population to determine its origin by comparing the density and temperature with the neutral density and magnetic field strength. We find that the warm electron population is actually two separate sub-populations: electron distributions with temperatures above 8.6 eV and electron distributions with temperatures below 8.6 eV. The two sub-populations have different relationships between their density and temperature. Moreover, the two sub-populations are affected by different drivers. The hotter sub-population temperature is strongly correlated with neutral density, while the cooler sub-population is unaffected by neutral density and is only weakly correlated with magnetic field strength. We suggest that the population with temperatures above 8.6 eV is being heated by lower hybrid waves driven by counterstreaming solar wind protons and newly formed, cometary ions created in localized, dense neutral streams. To the best of our knowledge, this represents the first observations of cometary electrons heated through wave-particle interactions.

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  • 84.
    Brown, P.
    et al.
    Imperial Coll London, Blackett Lab, London, England.
    Auster, U.
    TU Braunschweig, Braunschweig, Germany.
    Bergman, Jan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Fredriksson, Jesper
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Kasaba, Y.
    Tohoku Univ, Sendai, Miyagi, Japan.
    Mansour, M.
    Ecole Polytech, Lab Phys Plasmas, Palaiseau, France.
    Pollinger, A.
    Austrian Acad Sci, Space Res Inst, Vienna, Austria.
    Baughen, R.
    Imperial Coll London, Blackett Lab, London, England.
    Berglund, Martin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Hercik, D.
    TU Braunschweig, Braunschweig, Germany.
    Misawa, H.
    Tohoku Univ, Sendai, Miyagi, Japan.
    Retino, A.
    Ecole Polytech, Lab Phys Plasmas, Palaiseau, France.
    Bendyk, M.
    Imperial Coll London, Blackett Lab, London, England.
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Vienna, Austria.
    Cecconi, B.
    Observ Paris, LESIA, Meudon, France.
    Dougherty, M. K.
    Imperial Coll London, Blackett Lab, London, England.
    Fischer, G.
    Austrian Acad Sci, Space Res Inst, Vienna, Austria.
    Meeting the Magnetic Emc Challenges for the In-Situ Field Measurements on the Juice Mission2019In: Proceedings of 2019 ESA Workshop on Aerospace EMC (Aerospace EMC), IEEE, 2019Conference paper (Refereed)
    Abstract [en]

    The JUICE (JUpiter ICy moon Explorer) mission features instrument designs tailored to meet the specific challenges of the respective measuring environment, including EMC constraints. We describe the magnetic field science requirements for this mission and show how they drive the EMC requirements on the spacecraft and selected in-situ instrument configurations. We describe the results of two mutual interference campaigns and discuss the design mitigations employed in order to realise in-situ magnetic and electric field data in-flight with the accuracy required to meet very challenging mission science goals.

  • 85.
    Buchert, Stephan C.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Eriksson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Gill, Reine
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Nilsson, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Åhlén, Lennart
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Wahlund, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Knudsen, David
    Univ Calgary, Calgary, AB, Canada..
    Burchill, Johnathan
    Univ Calgary, Calgary, AB, Canada..
    Archer, William
    Univ Calgary, Calgary, AB, Canada..
    Kouznetsov, Alexei
    Univ Calgary, Calgary, AB, Canada..
    Stricker, Nico
    ESA ESTEC, Noordwijk, Netherlands..
    Bouridah, Abderrazak
    ESA ESTEC, Noordwijk, Netherlands..
    Bock, Ralph
    ESA ESTEC, Noordwijk, Netherlands..
    Haggstrom, Ingemar
    EISCAT Sci Assoc, Headquarters, Kiruna, Sweden..
    Rietveld, Michael
    EISCAT Sci Assoc, Tromso, Norway..
    Gonzalez, Sixto
    Natl Astron & Ionosphere Ctr, Arecibo, PR USA..
    Aponte, Nestor
    Natl Astron & Ionosphere Ctr, Arecibo, PR USA..
    First results from the Langmuir probes on the Swarm satellites2014In: 2014 XXXITH URSI General Assembly And Scientific Symposium (URSI GASS), 2014Conference paper (Refereed)
  • 86.
    Buchert, Stephan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Tsuda, T.
    Fujii, R.
    Nozawa, S.
    The Pedersen current carried by electrons: a non-linear response of the ionosphere to magnetospheric forcing2008In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 26, no 9, p. 2837-2844Article in journal (Refereed)
    Abstract [en]

    Observations by the EISCAT Svalbard radar show that electron temperatures T-e in the cusp electrojet reach up to about 4000 K. The heat is tapped and converted from plasma convection in the near Earth space by a Pedersen current that is carried by electrons due to the presence of irregularities and their demagnetising effect. The heat is transfered to the neutral gas by collisions. In order to enhance T-e to such high temperatures the maximally possible dissipation at 50% demagnetisation must nearly be reached. The effective Pedersen conductances are found to be enhanced by up to 60% compared to classical values. Conductivities and conductances respond significantly to variations of the electric field strength E, and "Ohm's law" for the ionosphere becomes non-linear for large E.

  • 87.
    Buchert, Stephan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Zangerl, Franz
    Sust, Manfred
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Eriksson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Wahlund, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Opgenoorth, Hermann
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    SWARM observations of equatorial electron densities and topside GPS track losses2015In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 42, no 7, p. 2088-2092Article in journal (Refereed)
    Abstract [en]

    The SWARM satellites have both upward looking GPS receivers and Langmuir probes. The receivers repeatedly lost track of the L1 band signal in January-February 2014 at postsunset hours, when SWARM was at nearly 500km altitude. This indicates that the signal was disturbed by ionospheric irregularities at this height and above. The track losses occurred right at density gradients associated with equatorial plasma bubbles and predominantly where the measured background density was highest. The signal showed strong phase scintillations rather than in amplitude, indicating that SWARM might be in the near field of an ionospheric phase screen. Density biteouts, depletions between steep gradients, were up to almost 3 orders of magnitude deep in the background of a more shallow trough centered at the magnetic equator. Comparison between satellites shows that the biteout structure strongly varied in longitude over approximate to 100km and has in north-south steep walls.

  • 88. Bunce, E. J.
    et al.
    Grodent, D. C.
    Jinks, S. L.
    Andrews, David J.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Badman, S. V.
    Coates, A. J.
    Cowley, S. W. H.
    Dougherty, M. K.
    Kurth, W. S.
    Mitchell, D. G.
    Provan, G.
    Cassini nightside observations of the oscillatory motion of Saturn's northern auroral oval2014In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, Vol. 119, no 5, p. 3528-3543Article in journal (Refereed)
    Abstract [en]

    In recent years we have benefitted greatly from the first in-orbit multi-wavelength images of Saturn's polar atmosphere from the Cassini spacecraft. Specifically, images obtained from the Cassini UltraViolet Imaging Spectrograph (UVIS) provide an excellent view of the planet's auroral emissions, which in turn give an account of the large-scale magnetosphere-ionosphere coupling and dynamics within the system. However, obtaining near-simultaneous views of the auroral regions with in situ measurements of magnetic field and plasma populations at high latitudes is more difficult to routinely achieve. Here we present an unusual case, during Revolution 99 in January 2009, where UVIS observes the entire northern UV auroral oval during a 2h interval while Cassini traverses the magnetic flux tubes connecting to the auroral regions near 21 LT, sampling the related magnetic field, particle, and radio and plasma wave signatures. The motion of the auroral oval evident from the UVIS images requires a careful interpretation of the associated latitudinally oscillating magnetic field and auroral field-aligned current signatures, whereas previous interpretations have assumed a static current system. Concurrent observations of the auroral hiss (typically generated in regions of downward directed field-aligned current) support this revised interpretation of an oscillating current system. The nature of the motion of the auroral oval evident in the UVIS image sequence, and the simultaneous measured motion of the field-aligned currents (and related plasma boundary) in this interval, is shown to be related to the northern hemisphere magnetosphere oscillation phase. This is in agreement with previous observations of the auroral oval oscillatory motion.

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  • 89.
    Burch, J. L.
    et al.
    Southwest Res Inst, San Antonio, TX 78238 USA.
    Dokgo, K.
    Southwest Res Inst, San Antonio, TX 78238 USA.
    Hwang, K. J.
    Southwest Res Inst, San Antonio, TX 78238 USA.
    Torbert, R. B.
    Southwest Res Inst, San Antonio, TX 78238 USA;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Webster, J. M.
    Rice Univ, Dept Phys & Astron, Houston, TX USA.
    Ergun, R. E.
    Univ Colorado, LASP, Boulder, CO 80309 USA.
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Allen, R. C.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA.
    Chen, L-J
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Wang, S.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA.
    Genestreti, K. J.
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.
    Russell, C. T.
    Univ Calif Los Angeles, Earth & Planetary Sci, Los Angeles, CA USA.
    Strangeway, R. J.
    Univ Calif Los Angeles, Earth & Planetary Sci, Los Angeles, CA USA.
    Le Contel, O.
    Univ Paris Sud, Observ Paris, Sorbonne Univ, Lab Phys Plasmas,CNRS,Ecole Polytech, Paris, France.
    High-Frequency Wave Generation in Magnetotail Reconnection: Linear Dispersion Analysis2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 8, p. 4089-4097Article in journal (Refereed)
    Abstract [en]

    Plasma and wave measurements from the NASA Magnetospheric Multiscale mission are presented for magnetotail reconnection events on 3 July and 11 July 2017. Linear dispersion analyses were performed using distribution functions comprising up to six drifting bi-Maxwellian distributions. In both events electron crescent-shaped distributions are shown to be responsible for upper hybrid waves near the X-line. In an adjacent location within the 3 July event a monodirectional field-aligned electron beam drove parallel-propagating beam-mode waves. In the 11 July event an electron distribution consisting of a drifting core and two crescents was shown to generate upper-hybrid and beam-mode waves at three different frequencies, explaining the observed broadband waves. Multiple harmonics of the upper hybrid waves were observed but cannot be explained by the linear dispersion analysis since they result from nonlinear beam interactions. Plain Language Summary Magnetic reconnection is a process that occurs throughout the universe in ionized gases (plasmas) containing embedded magnetic fields. This process converts magnetic energy to electron and ion energy, causing phenomena such as solar flares and auroras. The NASA Magnetospheric Multiscale mission has shown that in magnetic reconnection regions there are intense electric field oscillations or waves and that electrons form crescent and beam-like populations propagating both along and perpendicular to the magnetic field. This study shows that the observed electron populations are responsible for high-frequency waves including their propagation directions and frequency ranges.

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  • 90.
    Burch, J. L.
    et al.
    Southwest Res Inst, San Antonio, TX 78238 USA.
    Ergun, R. E.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Cassak, P. A.
    Univ Virginia, Dept Phys & Astron, Morgantown, WV USA..
    Webster, J. M.
    Rice Univ, Dept Phys & Astron, Houston, TX USA..
    Torbert, R. B.
    Southwest Res Inst, San Antonio, USA.;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Rager, A. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.;Catholic Univ Amer, Dept Phys, Washington, DC 20064 USA..
    Hwang, K. -J
    Southwest Res Inst, San Antonio, TX 78238 USA.
    Phan, T. D.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Genestreti, K. J.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Allen, R. C.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Chen, L. -J
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA.
    Wang, S.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Gershman, D.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Le Contel, O.
    Univ Paris Sud, Observ Paris, Lab Phys Plasmas, CNRS,Ecole Polytech,UPMC Univ Paris 06, Paris, France..
    Russell, C. T.
    Univ Calif Los Angeles, Dept Earth & Planetary Sci, Los Angeles, CA USA..
    Strangeway, R. J.
    Univ Calif Los Angeles, Dept Earth & Planetary Sci, Los Angeles, CA USA..
    Wilder, F. D.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Hesse, M.
    Univ Bergen, Dept Phys & Technol, Bergen, Norway..
    Drake, J. F.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Swisdak, M.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Price, L. M.
    Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Shay, M. A.
    Univ Delaware, Dept Phys & Astron, Newark, DE 19716 USA..
    Lindqvist, P. -A
    Royal Inst Technol, Dept Space & Plasma Phys, Stockholm, Sweden.
    Pollock, C. J.
    Denali Sci, Healy, AK USA..
    Denton, R. E.
    Dartmouth Coll, Dept Phys & Astron, Hanover, NH 03755 USA..
    Newman, D. L.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Localized Oscillatory Energy Conversion in Magnetopause Reconnection2018In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 45, no 3, p. 1237-1245Article in journal (Refereed)
    Abstract [en]

    Data from the NASA Magnetospheric Multiscale mission are used to investigate asymmetric magnetic reconnection at the dayside boundary between the Earth's magnetosphere and the solar wind. High-resolution measurements of plasmas and fields are used to identify highly localized (similar to 15 electron Debye lengths) standing wave structures with large electric field amplitudes (up to 100 mV/m). These wave structures are associated with spatially oscillatory energy conversion, which appears as alternatingly positive and negative values of J . E. For small guide magnetic fields the wave structures occur in the electron stagnation region at the magnetosphere edge of the electron diffusion region. For larger guide fields the structures also occur near the reconnection X-line. This difference is explained in terms of channels for the out-of-plane current (agyrotropic electrons at the stagnation point and guide field-aligned electrons at the X-line).

  • 91.
    Burch, J. L.
    et al.
    Southwest Res Inst, San Antonio, TX USA..
    Torbert, R. B.
    Southwest Res Inst, San Antonio, TX USA.;Univ New Hampshire, Durham, NH 03824 USA..
    Phan, T. D.
    Univ Calif Berkeley, Berkeley, CA 94720 USA..
    Chen, L. -J
    Moore, T. E.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Ergun, R. E.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Eastwood, J. P.
    Univ London Imperial Coll Sci Technol & Med, Blackett Lab, London, England..
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Cassak, P. A.
    W Virginia Univ, Morgantown, WV 26506 USA..
    Argall, M. R.
    Univ New Hampshire, Durham, NH 03824 USA..
    Wang, S.
    Univ Maryland, College Pk, MD 20742 USA..
    Hesse, M.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Pollock, C. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Nakamura, R.
    Austrian Acad Sci, Space Res Inst, A-8010 Graz, Austria..
    Mauk, B. H.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Fuselier, S. A.
    Southwest Res Inst, San Antonio, TX USA..
    Russell, C. T.
    Univ Calif Los Angeles, Los Angeles, CA USA..
    Strangeway, R. J.
    Univ Calif Los Angeles, Los Angeles, CA USA..
    Drake, J. F.
    Univ Maryland, College Pk, MD 20742 USA..
    Shay, M. A.
    Univ Delaware, Newark, DE USA..
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Lindqvist, P. -A
    Marklund, G.
    Royal Inst Technol, Stockholm, Sweden..
    Wilder, F. D.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Young, D. T.
    Southwest Res Inst, San Antonio, TX USA..
    Torkar, K.
    Austrian Acad Sci, Space Res Inst, A-8010 Graz, Austria..
    Goldstein, J.
    Southwest Res Inst, San Antonio, TX USA..
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Avanov, L. A.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Oka, M.
    Univ Calif Berkeley, Berkeley, CA 94720 USA..
    Baker, D. N.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Jaynes, A. N.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Goodrich, K. A.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Cohen, I. J.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Turner, D. L.
    Aerosp Corp, El Segundo, CA 90245 USA..
    Fennell, J. F.
    Aerosp Corp, El Segundo, CA 90245 USA..
    Blake, J. B.
    Aerosp Corp, El Segundo, CA 90245 USA..
    Clemmons, J.
    Aerosp Corp, El Segundo, CA 90245 USA..
    Goldman, M.
    Univ Colorado, Boulder, CO 80309 USA..
    Newman, D.
    Univ Colorado, Boulder, CO 80309 USA..
    Petrinec, S. M.
    Lockheed Martin Adv Technol Ctr, Palo Alto, CA USA..
    Trattner, K. J.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Lavraud, B.
    Inst Rech Astrophys & Planetol, Toulouse, France..
    Reiff, P. H.
    Rice Univ, Dept Phys & Astron, Houston, TX USA..
    Baumjohann, W.
    Austrian Acad Sci, Space Res Inst, A-8010 Graz, Austria..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, A-8010 Graz, Austria..
    Steller, M.
    Austrian Acad Sci, Space Res Inst, A-8010 Graz, Austria..
    Lewis, W.
    Southwest Res Inst, San Antonio, TX USA..
    Saito, Y.
    Inst Space & Astronaut Sci, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229, Japan..
    Coffey, V.
    NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA..
    Chandler, M.
    NASA, George C Marshall Space Flight Ctr, Huntsville, AL 35812 USA..
    Electron-scale measurements of magnetic reconnection in space2016In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 352, no 6290, p. 1189-+Article, review/survey (Refereed)
    Abstract [en]

    Magnetic reconnection is a fundamental physical process in plasmas whereby stored magnetic energy is converted into heat and kinetic energy of charged particles. Reconnection occurs in many astrophysical plasma environments and in laboratory plasmas. Using measurements with very high time resolution, NASA's Magnetospheric Multiscale (MMS) mission has found direct evidence for electron demagnetization and acceleration at sites along the sunward boundary of Earth's magnetosphere where the interplanetary magnetic field reconnects with the terrestrial magnetic field. We have (i) observed the conversion of magnetic energy to particle energy; (ii) measured the electric field and current, which together cause the dissipation of magnetic energy; and (iii) identified the electron population that carries the current as a result of demagnetization and acceleration within the reconnection diffusion/dissipation region.

  • 92.
    Burch, J. L.
    et al.
    Southwest Res Inst, San Antonio, TX, USA.
    Webster, J. M.
    Rice Univ, Dept Phys & Astron, Houston, TX USA.
    Genestreti, K. J.
    Austrian Acad Sci, Space Res Inst, Graz, Austria.
    Torbert, R. B.
    Southwest Res Inst, San Antonio, TX, USA; Univ New Hampshire, Dept Phys, Durham, NH, USA.
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Fuselier, S. A.
    Southwest Res Inst, San Antonio, TX, USA.
    Dorelli, J. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Rager, A. C.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA; Catholic Univ Amer, Dept Phys, Washington DC, USA..
    Phan, T. D.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA, USA.
    Allen, R. C.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA.
    Chen, L. -J
    Univ Maryland, Dept Astron, College Pk, MD, USA.
    Wang, S.
    Univ Maryland, Dept Astron, College Pk, MD, USA.
    Le Contel, O.
    Univ Paris Sud, UPMC Univ Paris 06, Lab Phys Plasmas, CNRS, Ecole Polytech,Observ Paris, Paris, France.
    Russell, C. T.
    Univ Calif Los Angeles, Earth & Planetary Sci, Los Angeles, CA, USA.
    Strangeway, R. J.
    Univ Calif Los Angeles, Earth & Planetary Sci, Los Angeles, CA, USA.
    Ergun, R. E.
    Univ Colorado, LASP, Boulder, CO, USA.
    Jaynes, A. N.
    Univ Iowa, Dept Phys & Astron, Iowa City, IA, USA.
    Lindqvist, P. -A
    Royal Inst Technol, Stockholm, Sweden.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Wilder, F. D.
    Univ Colorado, LASP, Boulder, CO, USA.
    Hwang, K. -J
    Southwest Res Inst, San Antonio, TX, USA.
    Goldstein, J.
    Southwest Res Inst, San Antonio, TX, USA.
    Wave Phenomena and Beam-Plasma Interactions at the Magnetopause Reconnection Region2018In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 123, no 2, p. 1118-1133Article in journal (Refereed)
    Abstract [en]

    This paper reports on Magnetospheric Multiscale observations of whistler mode chorus and higher-frequency electrostatic waves near and within a reconnection diffusion region on 23 November 2016. The diffusion region is bounded by crescent-shaped electron distributions and associated dissipation just upstream of the X-line and by magnetic field-aligned currents and electric fields leading to dissipation near the electron stagnation point. Measurements were made southward of the X-line as determined by southward directed ion and electron jets. We show that electrostatic wave generation is due to magnetosheath electron beams formed by the electron jets as they interact with a cold background plasma and more energetic population of magnetospheric electrons. On the magnetosphere side of the X-line the electron beams are accompanied by a strong perpendicular electron temperature anisotropy, which is shown to be the source of an observed rising-tone whistler mode chorus event. We show that the apex of the chorus event and the onset of electrostatic waves coincide with the opening of magnetic field lines at the electron stagnation point.

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  • 93.
    Cao, D.
    et al.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China.
    Fu, H. S.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China.
    Cao, J. B.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China.
    Wang, T. Y.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China.
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Chen, Z. Z.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China.
    Peng, F. Z.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China.
    Huang, S. Y.
    Wuhan Univ, Sch Elect & Informat, Wuhan, Peoples R China.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Russell, C. T.
    Univ Calif Los Angeles, Inst Geophys & Planetary Phys, Los Angeles, CA 90024 USA.
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Lindqvist, P. -A
    Torbert, R. B.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA.
    Ergun, R. E.
    Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA.
    Le Contel, O.
    UPMC, Ecole Polytech, CNRS, Lab Phys Plasmas, Palaiseau, France.
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA.
    MMS observations of whistler waves in electron diffusion region2017In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 44, no 9, p. 3954-3962Article in journal (Refereed)
    Abstract [en]

    Whistler waves that can produce anomalous resistivity by affecting electrons' motion have been suggested as one of the mechanisms responsible for magnetic reconnection in the electron diffusion region (EDR). Such type of waves, however, has rarely been observed inside the EDR so far. In this study, we report such an observation by Magnetospheric Multiscale (MMS) mission. We find large-amplitude whistler waves propagating away from the X line with a very small wave-normal angle. These waves are probably generated by the perpendicular temperature anisotropy of the -300eV electrons inside the EDR, according to our analysis of dispersion relation and cyclotron resonance condition; they significantly affect the electron-scale dynamics of magnetic reconnection and thus support previous simulations.

  • 94. Carbone, V.
    et al.
    Perri, S.
    Yordanova, Emiliya
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Veltri, P.
    Bruno, R.
    Khotyaintsev, Yuri
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    André, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Sign-Singularity of the Reduced Magnetic Helicity in the Solar Wind Plasma2010In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 104, no 18, p. 181101-Article in journal (Refereed)
    Abstract [en]

    We investigate the scaling laws of a signed measure derived from the reduced magnetic helicity which has been determined from Cluster data in the solar wind. This quantifies the handedness of the magnetic field; namely, it can be related to the polarization of the magnetic field fluctuations (right or left hand). The measure results to be sign-singular; that is, we do not observe any scale-dependent effect at the ion-and at electron-cyclotron frequencies. Cancellations between right-and left-hand polarizations go on in the dispersive or dissipative range, beyond the electron-cyclotron frequency. This means that the mechanism responsible for the generation of the dispersive or dissipative range is rather insensitive to the polarization of the magnetic field fluctuations.

  • 95. Carr, C.
    et al.
    Cupido, E.
    Lee, C. G. Y.
    Balogh, A.
    Beek, T.
    Burch, J. L.
    Dunford, C. N.
    Eriksson, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Gill, Reine
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Glassmeier, K. H.
    Goldstein, R.
    Lagoutte, D.
    Lundin, R.
    Lundin, K.
    Lybekk, B.
    Michau, J. L.
    Musmann, G.
    Nilsson, H.
    Pollock, C.
    Richter, I.
    Trotignon, J. G.
    RPC: The rosetta plasma consortium2007In: Space Science Reviews, ISSN 0038-6308, E-ISSN 1572-9672, Vol. 128, no 1-4, p. 629-647Article, review/survey (Refereed)
    Abstract [en]

    The Rosetta Plasma Consortium (RPC) will make in-situ measurements of the plasma enviromnent of comet 67P/Churyumov-Gerasimenko. The consortium will provide the complementary data sets necessary for an understanding of the plasma processes in the inner coma, and the structure and evolution of the coma with the increasing cometary activity. Five sensors have been selected to achieve this: the Ion and Electron Sensor (IES), the Ion Composition Analyser (ICA), the Langmuir Probe (LAP), the Mutual Impedance Probe (MIP) and the Magnetometer (MAG). The sensors interface to the spacecraft through the Plasma Interface Unit (PIU). The consortium approach allows for scientific, technical and operational coordination, and makes Optimum use of the available mass and power resources.

  • 96. Chasapis, A.
    et al.
    Retino, A.
    Sahraoui, F.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Sundkvist, D.
    Greco, A.
    Sorriso-Valvo, L.
    Canu, P.
    Thin Current Sheets and Associated Electron Heating in Turbulent Space Plasma2015In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 804, no 1, article id L1Article in journal (Refereed)
    Abstract [en]

    Intermittent structures, such as thin current sheets, are abundant in turbulent plasmas. Numerical simulations indicate that such current sheets are important sites of energy dissipation and particle heating occurring at kinetic scales. However, direct evidence of dissipation and associated heating within current sheets is scarce. Here, we show a new statistical study of local electron heating within proton-scale current sheets by using high-resolution spacecraft data. Current sheets are detected using the Partial Variance of Increments (PVI) method which identifies regions of strong intermittency. We find that strong electron heating occurs in high PVI (>3) current sheets while no significant heating occurs in low PVI cases (<3), indicating that the former are dominant for energy dissipation. Current sheets corresponding to very high PVI (>5) show the strongest heating and most of the time are consistent with ongoing magnetic reconnection. This suggests that reconnection is important for electron heating and dissipation at kinetic scales in turbulent plasmas.

  • 97.
    Chasapis, Alexandros
    et al.
    Univ Delaware, Newark, DC USA..
    Matthaeus, W. H.
    Univ Delaware, Newark, DC USA..
    Parashar, T. N.
    Univ Delaware, Newark, DC USA..
    LeContel, O.
    Lab Phys Plasmas, Paris, France..
    Retino, A.
    Lab Phys Plasmas, Paris, France..
    Breuillard, H.
    Lab Phys Plasmas, Paris, France..
    Khotyaintsev, Yuri
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vaivads, Andris
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Lavraud, B.
    Univ Toulouse UPS, Inst Rech Astrophys & Plantol, Toulouse, France.;Ctr Natl Rech Sci, UMR 5277, Toulouse, France..
    Eriksson, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Moore, T. E.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA..
    Torbert, R. B.
    Univ New Hampshire, Durham, NH 03824 USA..
    Lindqvist, P. -A
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO USA..
    Marklund, G.
    Royal Inst Technol, Stockholm, Sweden..
    Goodrich, K. A.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO USA..
    Wilder, F. D.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO USA..
    Chutter, M.
    Univ New Hampshire, Durham, NH 03824 USA..
    Needell, J.
    Univ New Hampshire, Durham, NH 03824 USA..
    Rau, D.
    Univ New Hampshire, Durham, NH 03824 USA..
    Dors, I.
    Univ New Hampshire, Durham, NH 03824 USA..
    Russell, C. T.
    Univ Calif Los Angeles, Los Angeles, CA USA..
    Le, G.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Magnes, W.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Strangeway, R. J.
    Univ Calif Los Angeles, Los Angeles, CA USA..
    Bromund, K. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Leinweber, H. K.
    Univ Calif Los Angeles, Los Angeles, CA USA..
    Plaschke, F.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Fischer, D.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Anderson, B. J.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Pollock, C. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Paterson, W. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Dorelli, J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Avanov, L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Saito, Y.
    Inst Space & Astronaut Sci, Sagamihara, Kanagawa, Japan..
    Electron Heating at Kinetic Scales in Magnetosheath Turbulence2017In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 836, no 2, article id 247Article in journal (Refereed)
    Abstract [en]

    We present a statistical study of coherent structures at kinetic scales, using data from the Magnetospheric Multiscale mission in the Earth's magnetosheath. We implemented the multi-spacecraft partial variance of increments (PVI) technique to detect these structures, which are associated with intermittency at kinetic scales. We examine the properties of the electron heating occurring within such structures. We find that, statistically, structures with a high PVI index are regions of significant electron heating. We also focus on one such structure, a current sheet, which shows some signatures consistent with magnetic reconnection. Strong parallel electron heating coincides with whistler emissions at the edges of the current sheet.

  • 98.
    Chasapis, Alexandros
    et al.
    Univ Delaware, Newark, DE 19716 USA.
    Matthaeus, W. H.
    Univ Delaware, Newark, DE 19716 USA.
    Parashar, T. N.
    Univ Delaware, Newark, DE 19716 USA.
    Wan, M.
    South Univ Sci & Technol China, Shenzhen, Guangdong, Peoples R China.
    Haggerty, C. C.
    Univ Delaware, Newark, DE 19716 USA.
    Pollock, C. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Paterson, W. R.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Dorelli, J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Gershman, D. J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Torbert, R. B.
    Univ New Hampshire, Durham, NH 03824 USA.
    Russell, C. T.
    Univ Calif Los Angeles, Los Angeles, CA USA.
    Lindqvist, P. -A
    Khotyaintsev, Yuri
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Moore, T. E.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80309 USA.
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA.
    In Situ Observation of Intermittent Dissipation at Kinetic Scales in the Earth's Magnetosheath2018In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 856, no 1, article id L19Article in journal (Refereed)
    Abstract [en]

    We present a study of signatures of energy dissipation at kinetic scales in plasma turbulence based on observations by the Magnetospheric Multiscale mission (MMS) in the Earth's magnetosheath. Using several intervals, and taking advantage of the high-resolution instrumentation on board MMS, we compute and discuss several statistical measures of coherent structures and heating associated with electrons, at previously unattainable scales in space and time. We use the multi-spacecraft Partial Variance of Increments (PVI) technique to study the intermittent structure of the magnetic field. Furthermore, we examine a measure of dissipation and its behavior with respect to the PVI as well as the current density. Additionally, we analyze the evolution of the anisotropic electron temperature and non-Maxwellian features of the particle distribution function. From these diagnostics emerges strong statistical evidence that electrons are preferentially heated in subproton-scale regions of strong electric current density, and this heating is preferentially in the parallel direction relative to the local magnetic field. Accordingly, the conversion of magnetic energy into electron kinetic energy occurs more strongly in regions of stronger current density, a finding consistent with several kinetic plasma simulation studies and hinted at by prior studies using lower resolution Cluster observations.

  • 99. Chaufray, J. Y.
    et al.
    Modolo, Ronan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Leblanc, F.
    Chanteur, G.
    Johnson, R. E.
    Luhmann, J. G.
    Mars solar wind interaction: Formation of the Martian corona and atmospheric loss to space2007In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 112, no E9, p. E09009-Article, review/survey (Refereed)
    Abstract [en]

    A three- dimensional ( 3- D) atomic oxygen corona of Mars is computed for periods of low and high solar activities. The thermal atomic oxygen corona is derived from a collisionless Chamberlain approach, whereas the nonthermal atomic oxygen corona is derived from Monte Carlo simulations. The two main sources of hot exospheric oxygen atoms at Mars are the dissociative recombination of O-2(+) between 120 and 300 km and the sputtering of the Martian atmosphere by incident O+ pickup ions. The reimpacting and escaping fluxes of pickup ions are derived from a 3- D hybrid model describing the interaction of the solar wind with our computed Martian oxygen exosphere. In this work it is shown that the role of the sputtering crucially depends on an accurate description of the Martian corona as well as of its interaction with the solar wind. The sputtering contribution to the total oxygen escape is smaller by one order of magnitude than the contribution due to the dissociative recombination. The neutral escape is dominant at both solar activities ( 1 x 10(25) s(-1) for low solar activity and 4 x 10(25) s(-1) for high solar activity), and the ion escape flux is estimated to be equal to 2 x 10(23) s(-1) at low solar activity and to 3.4 x 10(24) s(-1) at high solar activity. This work illustrates one more time the strong dependency of these loss rates on solar conditions. It underlines the difficulty of extrapolating the present measured loss rates to the past solar conditions without a better theoretical and observational knowledge of this dependency.

  • 100. Chen, L. -J
    et al.
    Hesse, M.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Wang, S.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Gershman, D.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Sci, Boulder, CO 80309 USA..
    Burch, J.
    Southwest Res Inst, San Antonio, TX USA..
    Bessho, N.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Torbert, R. B.
    Southwest Res Inst, San Antonio, TX USA.;Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Giles, B.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Webster, J.
    Rice Univ, Dept Phys & Astron, Houston, TX USA..
    Pollock, C.
    Denali Sci, Healy, AK USA..
    Dorelli, J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Moore, T.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Paterson, W.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Lavraud, B.
    Univ Toulouse, Inst Rech Astrophys & Planetol, Toulouse, France.;CNRS, UMR 5277, Toulouse, France..
    Strangeway, R.
    Univ Calif Los Angeles, Earth Planetary & Space Sci, Los Angeles, CA USA..
    Russell, C.
    Univ Calif Los Angeles, Earth Planetary & Space Sci, Los Angeles, CA USA..
    Khotyaintsev, Yuri
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Lindqvist, P. -A
    Avanov, L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Electron diffusion region during magnetopause reconnection with an intermediate guide field: Magnetospheric multiscale observations2017In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 122, no 5, p. 5235-5246Article in journal (Refereed)
    Abstract [en]

    An electron diffusion region (EDR) in magnetic reconnection with a guide magnetic field approximately 0.2 times the reconnecting component is encountered by the four Magnetospheric Multiscale spacecraft at the Earth's magnetopause. The distinct substructures in the EDR on both sides of the reconnecting current sheet are visualized with electron distribution functions that are 2 orders of magnitude higher cadence than ever achieved to enable the following new findings: (1) Motion of the demagnetized electrons plays an important role to sustain the reconnection current and contributes to the dissipation due to the nonideal electric field, (2) the finite guide field dominates over the Hall magnetic field in an electron-scale region in the exhaust and modifies the electron flow dynamics in the EDR, (3) the reconnection current is in part carried by inflowing field-aligned electrons in the magnetosphere part of the EDR, and (4) the reconnection electric field measured by multiple spacecraft is uniform over at least eight electron skin depths and corresponds to a reconnection rate of approximately 0.1. The observations establish the first look at the structure of the EDR under a weak but not negligible guide field.

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