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  • 101.
    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
  • 102.
    Boynton, R. J.
    et al.
    Univ Sheffield, Dept Automat Control & Syst Engn, Sheffield, S Yorkshire, England.
    Aryan, H.
    Univ Sheffield, Dept Automat Control & Syst Engn, Sheffield, S Yorkshire, England; Univ Calif Los Angeles, Dept Atmospher & Ocean Sci, Los Angeles, CA USA.
    Dimmock, Andrew P.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Balikhin, M. A.
    Univ Sheffield, Dept Automat Control & Syst Engn, Sheffield, S Yorkshire, England.
    System Identification of Local Time Electron Fluencies at Geostationary Orbit2020In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 125, no 11, article id e2020JA028262Article in journal (Refereed)
    Abstract [en]

    The electron fluxes at geostationary orbit measured by Geostationary Operational Environmental Satellite (GOES) 13, 14, and 15 spacecraft are modeled using system identification techniques. System identification, similar to machine learning, uses input-output data to train a model, which can then be used to provide forecasts. This study employs the nonlinear autoregressive moving average exogenous technique to deduce the electron flux models. The electron fluxes at geostationary orbit are known to vary in space and time, making it a spatiotemporal system, which complicates the modeling using system identification/machine learning approach. Therefore, the electron flux data are binned into 24 magnetic local time (MLT), and a separate model is developed for each of the 24 MLT bins. MLT models are developed for six of the GOES 13, 14, and 15 electron flux energy channels (75 keV, 150 keV, 275 keV, 475 keV, >800 keV, and >2 MeV). The models are assessed on separate test data by prediction efficiency (PE) and correlation coefficient (CC) and found these to vary by MLT and electron energy. The lowest energy of 75 keV at the midnight sector had a PE of 36.0 and CC of 59.3, which increased on the dayside to a PE of 66.9 and CC of 81.6. These metrics increased to the >2 MeV model, which had a low PE and CC of 63.0 and 81.8 on the nightside to a high of 80.3 and 90.8 on the dayside.

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    fulltext
  • 103. 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, 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.

  • 104.
    Branduardi-Raymont, G.
    et al.
    Univ Coll London, Mullard Space Sci Lab, Holmbury St Mary, Dorking RH5 6NT, Surrey, England..
    Berthomier, M.
    Lab Phys Plasmas, Paris, France..
    Bogdanova, Y. V.
    Rutherford Appleton Lab, Didcot, Oxon, England..
    Carter, J. A.
    Univ Leicester, Leicester, Leics, England..
    Collier, M.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Dimmock, Andrew P.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Dunlop, M.
    Rutherford Appleton Lab, Didcot, Oxon, England.;Beihang Univ, Sch Space & Environm, Beijing, Peoples R China..
    Fear, R. C.
    Univ Southampton, Southampton, Hants, England..
    Forsyth, C.
    Univ Coll London, Mullard Space Sci Lab, Holmbury St Mary, Dorking RH5 6NT, Surrey, England..
    Hubert, B.
    Univ Liege, Liege, Belgium..
    Kronberg, E. A.
    Univ Munich, Munich, Germany..
    Laundal, K. M.
    Univ Bergen, Bergen, Norway..
    Lester, M.
    Univ Leicester, Leicester, Leics, England..
    Milan, S.
    Univ Leicester, Leicester, Leics, England..
    Oksavik, K.
    Univ Bergen, Bergen, Norway..
    Ostgaard, N.
    Univ Bergen, Bergen, Norway..
    Palmroth, M.
    Univ Helsinki, Helsinki, Finland..
    Plaschke, F.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Porter, F. S.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Rae, I. J.
    Northumbria Univ, Newcastle Upon Tyne, Tyne & Wear, England..
    Read, A.
    Univ Leicester, Leicester, Leics, England..
    Samsonov, A. A.
    Univ Coll London, Mullard Space Sci Lab, Holmbury St Mary, Dorking RH5 6NT, Surrey, England..
    Sembay, S.
    Univ Leicester, Leicester, Leics, England..
    Shprits, Y.
    German Res Ctr Geosci, Potsdam, Germany..
    Sibeck, D. G.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Walsh, B.
    Boston Univ, Boston, MA 02215 USA..
    Yamauchi, M.
    Swedish Inst Space Phys, Kiruna, Sweden..
    Exploring solar-terrestrial interactions via multiple imaging observers2022In: Experimental astronomy, ISSN 0922-6435, E-ISSN 1572-9508, Vol. 54, no 2-3, p. 361-390Article in journal (Refereed)
    Abstract [en]

    How does solar wind energy flow through the Earth's magnetosphere, how is it converted and distributed? is the question we want to address. We need to understand how geomagnetic storms and substorms start and grow, not just as a matter of scientific curiosity, but to address a clear and pressing practical problem: space weather, which can influence the performance and reliability of our technological systems, in space and on the ground, and can endanger human life and health. Much knowledge has already been acquired over the past decades, particularly by making use of multiple spacecraft measuring conditions in situ, but the infant stage of space weather forecasting demonstrates that we still have a vast amount of learning to do. A novel global approach is now being taken by a number of space imaging missions which are under development and the first tantalising results of their exploration will be available in the next decade. In this White Paper, submitted to ESA in response to the Voyage 2050 Call, we propose the next step in the quest for a complete understanding of how the Sun controls the Earth's plasma environment: a tomographic imaging approach comprising two spacecraft in highly inclined polar orbits, enabling global imaging of magnetopause and cusps in soft X-rays, of auroral regions in FUV, of plasmasphere and ring current in EUV and ENA (Energetic Neutral Atoms), alongside in situ measurements. Such a mission, encompassing the variety of physical processes determining the conditions of geospace, will be crucial on the way to achieving scientific closure on the question of solar-terrestrial interactions.

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    FULLTEXT01
  • 105.
    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
  • 106.
    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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  • 107.
    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.

  • 108.
    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.

  • 109.
    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.

  • 110.
    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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  • 111.
    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.

  • 112.
    Buchert, Stephan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Entangled dynamos and Joule heating in the Earth's ionosphere2020In: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 38, p. 1019-1030Article in journal (Refereed)
    Abstract [en]

    The Earth's neutral atmosphere is the driver of the well-known solar quiet (Sq) and other magnetic variations observed for more than 100 years. Yet the understanding of how the neutral wind can accomplish a dynamo effect has been incomplete. A new viable model is presented where a dynamo effect is obtained only in the case of winds perpendicular to the magnetic field B that do not map along B. Winds where uxB is constant have no effect. We identify Sq as being driven by wind differences at magnetically conjugate points and not by a neutral wind per se. The view of two different but entangled dynamos is favoured, with some conceptual analogy to quantum mechanical states. Because of the large preponderance of the neutral gas mass over the ionized component in the Earth's ionosphere, the dominant effect of the plasma adjusting to the winds is Joule heating. The amount of global Joule heating power from Sq is estimated, with uncertainties, to be much lower than Joule heating from ionosphere-magnetosphere coupling at high latitudes in periods of strong geomagnetic activity. However, on average both contributions could be relatively comparable. The global contribution of heating by ionizing solar radiation in the same height range should be 2-3 orders of magnitude larger.

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  • 113.
    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)
  • 114.
    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.

  • 115.
    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.

  • 116. 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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  • 117.
    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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  • 118.
    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).

  • 119.
    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.

  • 120.
    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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    fulltext
  • 121.
    Burne, Sofia
    et al.
    UBA CONICET, IAFE, Buenos Aires, Argentina..
    Bertucci, Cesar
    UBA CONICET, IAFE, Buenos Aires, Argentina..
    Sergis, Nick
    Acad Athens, Athens, Greece..
    Morales, Laura F.
    UBA CONICET, INFIP, Buenos Aires, Argentina..
    Achilleos, Nicholas
    UCL, Ctr Planetary Sci, Dept Phys & Astron, London, England..
    Sanchez-Cano, Beatriz
    Univ Leicester, Sch Phys & Astron, Leicester, England..
    Collado-Vega, Yaireska
    NASA Goddard Space Flight Ctr, Greenbelt, MD USA..
    Dasso, Sergio
    UBA CONICET, IAFE, Buenos Aires, Argentina..
    Edberg, Niklas J. T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Kurth, Bill S.
    Univ Iowa, Dept Phys & Astron, Iowa City, IA USA..
    Space Weather in the Saturn-Titan System2023In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 948, no 1, article id 37Article in journal (Refereed)
    Abstract [en]

    New evidence based on Cassini magnetic field and plasma data has revealed that the discovery of Titan outside Saturn's magnetosphere during the T96 flyby on 2013 December 1 was the result of the impact of two consecutive interplanetary coronal mass ejections (ICMEs) that left the Sun in 2013 early November and interacted with the moon and the planet. We study the dynamic evolution of Saturn's magnetopause and bow shock, which evidences a magnetospheric compression from late November 28 to December 4 (at least), under prevailing solar wind dynamic pressures of 0.16-0.3 nPa. During this interval, transient disturbances associated with the two ICMEs are observed, allowing for the identification of their magnetic structures. By analyzing the magnetic field direction, and the pressure balance in Titan's induced magnetosphere, we show that Cassini finds Saturn's moon embedded in the second ICME after being swept by its interplanetary shock and amid a shower of solar energetic particles that may have caused dramatic changes in the moon's lower ionosphere. Analyzing a list of Saturn's bow shock crossings during 2004-2016, we find that the magnetospheric compression needed for Titan to be in the supersonic solar wind can be generally associated with the presence of an ICME or a corotating interaction region. This leads to the conclusion that Titan would rarely face the pristine solar wind, but would rather interact with transient solar structures under extreme space weather conditions.

  • 122.
    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.

  • 123.
    Carbone, F.
    et al.
    Univ Calabria, Natl Res Council, Inst Atmospher Pollut Res, I-87036 Arcavacata Di Rende, Italy..
    Sorriso-Valvo, Luca
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Ist Sci & Tecnol Plasmi, CNR, Via Amendola 122-D, I-70126 Bari, Italy.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Steinvall, Konrad
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vecchio, A.
    Univ Paris Diderot, Sorbonne Univ, Univ PSL, Observ Paris, Sorbonne Paris Cite,5 Pl Jules Janssen, F-92195 Meudon, France.;Radboud Univ Nijmegen, Res Inst Math Astrophys & Particle Phys, Nijmegen, Netherlands..
    Telloni, D.
    Natl Inst Astrophys, Astrophys Observ Torino, Turin, Italy..
    Yordanova, Emiliya
    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.
    Edberg, Niklas J. T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Eriksson, Anders I.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Johansson, Erik P. G.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Vásconez, C. L.
    Escuela Politec Nacl, Dept Fis, Ladron de Guevara E11-253, Quito 170525, Ecuador..
    Maksimovic, M.
    Radboud Univ Nijmegen, Res Inst Math Astrophys & Particle Phys, Nijmegen, Netherlands..
    Bruno, R.
    Natl Inst Astrophys INAF, Inst Space Astrophys & Planetol IAPS, Via Fosso del Cavaliere 100, I-00133 Rome, Italy..
    D'Amicis, R.
    Natl Inst Astrophys INAF, Inst Space Astrophys & Planetol IAPS, Via Fosso del Cavaliere 100, I-00133 Rome, Italy..
    Bale, S. D.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA.;Univ Calif Berkeley, Phys Dept, Berkeley, CA 94720 USA..
    Chust, T.
    Univ Paris Saclay, Observ Paris, Sorbonne Univ, Ecole Polytech,LPP,CNRS, Paris, France..
    Krasnoselskikh, V.
    CNRS, LPC2E, 3A Ave Rech Sci, Orleans, France..
    Kretzschmar, M.
    CNRS, LPC2E, 3A Ave Rech Sci, Orleans, France.;Univ Orleans, Orleans, France..
    Lorfèvre, E.
    CNES, 18 Ave Edouard Belin, F-31400 Toulouse, France..
    Plettemeier, D.
    Tech Univ Dresden, Wurzburger Str 35, D-01187 Dresden, Germany..
    Soucek, J.
    Czech Acad Sci, Inst Atmospher Phys, Prague, Czech Republic..
    Steller, M.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Stverák, S.
    Czech Acad Sci, Inst Atmospher Phys, Prague, Czech Republic.;Czech Acad Sci, Astron Inst, Prague, Czech Republic..
    Trávnicek, P.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA.;Czech Acad Sci, Inst Atmospher Phys, Prague, Czech Republic..
    Vaivads, A.
    CNRS, LPC2E, 3A Ave Rech Sci, Orleans, France.;Royal Inst Technol, Sch Elect Engn & Comp Sci, Dept Space & Plasma Phys, Stockholm, Sweden..
    Horbury, T. S.
    Imperial Coll London, Blackett Lab, Space & Atmospher Phys, London SW7 2AZ, England..
    O'Brien, H.
    Imperial Coll London, Blackett Lab, Space & Atmospher Phys, London SW7 2AZ, England..
    Angelini, V.
    Imperial Coll London, Blackett Lab, Space & Atmospher Phys, London SW7 2AZ, England..
    Evans, V.
    Imperial Coll London, Blackett Lab, Space & Atmospher Phys, London SW7 2AZ, England..
    Statistical study of electron density turbulence and ion-cyclotron waves in the inner heliosphere: Solar Orbiter observations2021In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 656, article id A16Article in journal (Refereed)
    Abstract [en]

    Context. The recently released spacecraft potential measured by the RPW instrument on board Solar Orbiter has been used to estimate the solar wind electron density in the inner heliosphere.

    Aims. The measurement of the solar wind’s electron density, taken in June 2020, has been analysed to obtain a thorough characterization of the turbulence and intermittency properties of the fluctuations. Magnetic field data have been used to describe the presence of ion-scale waves.

    Methods. To study and quantify the properties of turbulence, we extracted selected intervals. We used empirical mode decomposition to obtain the generalized marginal Hilbert spectrum, equivalent to the structure functions analysis, which additionally reduced issues typical of non-stationary, short time series. The presence of waves was quantitatively determined by introducing a parameter describing the time-dependent, frequency-filtered wave power.

    Results. A well-defined inertial range with power-law scalng was found almost everywhere in the sample studied. However, the Kolmogorov scaling and the typical intermittency effects are only present in fraction of the samples. Other intervals have shallower spectra and more irregular intermittency, which are not described by models of turbulence. These are observed predominantly during intervals of enhanced ion frequency wave activity. Comparisons with compressible magnetic field intermittency (from the MAG instrument) and with an estimate of the solar wind velocity (using electric and magnetic field) are also provided to give general context and help determine the cause of these anomalous fluctuations.

  • 124.
    Carbone, Francesco
    et al.
    Univ Calabria, Natl Res Council, Inst Atmospher Pollut Res, I-87036 Arcavacata Di Rende, Italy..
    Alberti, Tommaso
    Natl Inst Astrophys, Inst Space Astrophys & Planetol, I-00133 Rome, Italy..
    Faranda, Davide
    Univ Paris Saclay, Lab Sci Climat & lEnvironnem, CEA Saclay lOrme Merisiers, UMR CEA CNRS UVSQ 8212, F-91191 Gif Sur Yvette, France.;London Math Lab, London W6 8RH, England.;PSL Res Univ, Ecole Normale Super, LMD, IPSL, F-75005 Paris, France..
    Telloni, Daniele
    Natl Inst Astrophys, Astrophys Observ Torino, I-10025 Pino Torinese, Italy..
    Consolini, Giuseppe
    Natl Inst Astrophys, Inst Space Astrophys & Planetol, I-00133 Rome, Italy..
    Sorriso-Valvo, Luca
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Inst Plasma Sci & Technol, Natl Res Council, I-70126 Bari, Italy..
    Local dimensionality and inverse persistence analysis of atmospheric turbulence in the stable boundary layer2022In: Physical review. E, ISSN 2470-0045, E-ISSN 2470-0053, Vol. 106, no 6, article id 064211Article in journal (Refereed)
    Abstract [en]

    The dynamics across different scales in the stable atmospheric boundary layer has been investigated by means of two metrics, based on instantaneous fractal dimensions and grounded in dynamical systems theory. The wind velocity fluctuations obtained from data collected during the Cooperative Atmosphere-Surface Exchange Study- 1999 experiment were analyzed to provide a local (in terms of scales) and an instantaneous (in terms of time) description of the fractal properties and predictability of the system. By analyzing the phase-space projections of the continuous turbulent, intermittent, and radiative regimes, a progressive transformation, characterized by the emergence of multiple low-dimensional clusters embedded in a high-dimensional shell and a two-lobe mirror symmetrical structure of the inverse persistence, have been found. The phase space becomes increasingly complex and anisotropic as the turbulent fluctuations become uncorrelated. The phase space is characterized by a three-dimensional structure for the continuous turbulent samples in a range of scales compatible with the inertial subrange, where the phase-space-filling turbulent fluctuations dominate the dynamics, and is low dimensional in the other regimes. Moreover, lower-dimensional structures present a stronger persistence than the higher-dimensional structures. Eventually, all samples recover a three-dimensional structure and higher persistence level at large scales, far from the inertial subrange. The two metrics obtained in the analysis can be considered as proxies for the decorrelation time and the local anisotropy in the turbulent flow.

  • 125.
    Carbone, Francesco
    et al.
    Univ Calabria, Natl Res Council, Inst Atmospher Pollut Res, I-87036 Arcavacata Di Rende, Italy.
    Telloni, Daniele
    Natl Inst Astrophys Astrophys Observ Torino, Via Osservatorio 20, I-10025 Pino Torinese, Italy.
    Yordanova, Emiliya
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Sorriso-Valvo, Luca
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. CNR, Ist Sci & Tecnol Plasmi, Via Amendola 112-D, I-70126 Bari, Italy.
    Modulation of Solar Wind Impact on the Earth's Magnetosphere during the Solar Cycle2022In: Universe, E-ISSN 2218-1997, Vol. 8, no 6, article id 330Article in journal (Refereed)
    Abstract [en]

    The understanding of extreme geomagnetic storms is one of the key issues in space weather. Such phenomena have been receiving increasing attention, especially with the aim of forecasting strong geomagnetic storms generated by high-energy solar events since they can severely perturb the near-Earth space environment. Here, the disturbance storm time index Dst, a crucial geomagnetic activity proxy for Sun-Earth interactions, is analyzed as a function of the energy carried by different solar wind streams. To determine the solar cycle activity influence on Dst, a 12-year dataset was split into sub-periods of maximum and minimum solar activity. Solar wind energy and geomagnetic activity were closely correlated for both periods of activity. Slow wind streams had negligible effects on Earth regardless of their energy, while high-speed streams may induce severe geomagnetic storming depending on the energy (kinetic or magnetic) carried by the flow. The difference between the two periods may be related to the higher rate of geo-effective events during the maximum activity, where coronal mass ejections represent the most energetic and geo-effective driver. During the minimum period, despite a lower rate of high energetic events, a moderate disturbance in the Dst index can be induced.

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  • 126.
    Carbone, Francesco
    et al.
    Univ Calabria, Inst Atmospher Pollut Res, Natl Res Council, I-87036 Arcavacata Di Rende, Italy..
    Telloni, Daniele
    Astrophys Observ Torino, Natl Inst Astrophys, Via Osservatorio 20, I-10025 Pino Torinese, Italy..
    Zank, Gary
    Univ Alabama Huntsville, CSPAR, Huntsville, AL 35899 USA.;Univ Alabama Huntsville, Dept Space Sci, Huntsville, AL 35899 USA..
    Sorriso-Valvo, L.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Swedish Inst Space Phys, Angstrom Lab, Lagerhyddsvagen 1, SE-75121 Uppsala, Sweden.;CNR, Ist Sci & Tecnol Plasmi, Via Amendola 122-D, I-70126 Bari, Italy..
    Transition to turbulence in a five-mode Galerkin truncation of two-dimensional magnetohydrodynamics2021In: Physical review. E, ISSN 2470-0045, E-ISSN 2470-0053, Vol. 104, no 2, article id 025201Article in journal (Refereed)
    Abstract [en]

    The chaotic dynamics of a low-order Galerkin truncation of the two-dimensional magnetohydrodynamic system, which reproduces the dynamics of fluctuations described by nearly incompressible magnetohydrodynamic in the plane perpendicular to a background magnetic field, is investigated by increasing the external forcing terms. Although this is the case closest to two-dimensional hydrodynamics, which shares some aspects with the classical Feigenbaum scenario of transition to chaos, the presence of magnetic fluctuations yields a very complex interesting route to chaos, characterized by the splitting into multiharmonic structures of the field amplitudes, and a mixing of phase-locking and free phase precession acting intermittently. When the background magnetic field lies in the plane, the system supports the presence of Alfven waves thus lowering the nonlinear interactions. Interestingly enough, the dynamics critically depends on the angle between the direction of the magnetic field and the reference system of the wave vectors. Above a certain critical angle, independently from the external forcing, a breakdown of the phase locking appears, accompanied with a suppression of the chaotic dynamics, replaced by a simple periodic motion.

  • 127.
    Carbone, Francesco
    et al.
    Univ Calabria, Inst Atmospher Pollut Res, CNR, I-87036 Arcavacata Di Rende, Italy..
    Telloni, Daniele
    Astrophys Observ Torino, Natl Inst Astrophys, Via Osservatorio 20, I-10025 Pino Torinese, Italy..
    Zank, Gary
    Univ Alabama, Ctr Space Plasma & Aeron Res CSPAR, Huntsville, AL 35899 USA.;Univ Alabama, Dept Space Sci, Huntsville, AL 35899 USA..
    Sorriso-Valvo, Luca
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. CNR, Ist Sci & Tecnol Plasmi, Via Amendola 122-D, I-70126 Bari, Italy..
    Chaotic advection and particle pairs diffusion in a low-dimensional truncation of two-dimensional magnetohydrodynamics2022In: Europhysics letters, ISSN 0295-5075, E-ISSN 1286-4854, Vol. 138, no 5, article id 53001Article in journal (Refereed)
    Abstract [en]

    The chaotic advection of fluid particle pairs is investigated though a low-order model of two-dimensional magnetohydrodynamic (MHD), where only five nonlinearly interacting modes are retained. The model is inthrinsically inhomogeneous and anisotropic because of the influence of large-scale fluctuations. Therefore, even though dynamically chaotic, the fields are unable to form the typical scaling laws of fully developed turbulence. Results show that a super-ballistic dynamics, reminiscent of the Richardson law of particle-pairs diffusion in turbulent flows, is robustly obtained using the truncated model. Indeed, even in the strongly reduced truncation presented here, particle diffusion in MHD turbulence has the same laws as the separation of velocity of particle pairs. The inherent anisotropy only affects the scaling of diffusivity, by enhancing the diffusion properties along one direction for small time-scales. Finally, when further anisotropy is introduced in the system through Alfven waves, fluid particles are trapped by these, and super-ballistic diffusion is replaced by Brownian-like diffusion. On the other hand, when the magnetic field is removed, the kinetic counterpart of the model does not show super-ballistic dynamics.

  • 128. 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.

  • 129. 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.

  • 130.
    Carter, J. A.
    et al.
    Univ Leicester, Sch Phys & Astron, Planetary Sci Grp, Univ Rd, Leicester LE1 7RH, Leics, England..
    Dunlop, M.
    Rutherford Appleton Lab Space, Sci Technol Facil Council, Didcot, Oxon, England.;Beihang Univ, Sch Space & Environm, Beijing 100191, Peoples R China.;Minist Ind & Informat Technol, Key Lab Space Environm Monitoring & Informat Proc, Beijing 100017, Peoples R China..
    Forsyth, C.
    UCL, Dept Space & Climate Phys, Mullard Space Sci Lab, Holmbury St Mary, Dorking RH5 6NT, Surrey, England..
    Oksavik, K.
    Birkeland Centre for Space Science, Department of Physics and Technology., University of Bergen, Bergen, Norway;Arctic Geophysics, University Centre in Svalbard, Longyearbyen, Norway.
    Donovon, E.
    Univ Calgary, Dept Phys & Astron, 2500 Univ Dr, Calgary, AB T2N 1N4, Canada..
    Kavanagh, A.
    British Antarct Survey, Cambridge, England..
    Milan, S. E.
    Univ Leicester, Sch Phys & Astron, Planetary Sci Grp, Univ Rd, Leicester LE1 7RH, Leics, England..
    Sergienko, T.
    Swedish Inst Space Phys, Kiruna, Sweden..
    Fear, R. C.
    Univ Southampton, West Highfield Campus, Univ Rd, Southampton SO17 1BJ, Hants, England..
    Sibeck, D. G.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA..
    Connors, M.
    Athabasca Univ, Athabasca, AB, Canada..
    Yeoman, T.
    Univ Leicester, Sch Phys & Astron, Planetary Sci Grp, Univ Rd, Leicester LE1 7RH, Leics, England..
    Tan, X.
    Beihang Univ, Sch Space & Environm, Beijing 100191, Peoples R China..
    Taylor, M. G. G. T.
    European Space Agcy, ESTEC, Noordwijk, Netherlands..
    McWilliams, K.
    Univ Saskatchewan, Saskatoon, SK, Canada..
    Gjerloev, J.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Barnes, R.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Billet, D. D.
    Univ Saskatchewan, Saskatoon, SK, Canada..
    Chisham, G.
    British Antarctic Survey, Cambridge, UK.
    Dimmock, Andrew P.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Freeman, M. P.
    British Antarct Survey, Cambridge, England..
    Han, D. -S
    Tongji University, Shanghai 200092, China.
    Hartinger, M. D.
    Space Sci Inst, Ctr Space Plasma Phys, 4765 Walnut St Suite B, Boulder, CO 80301 USA..
    Hsieh, S. -YW.
    The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA.
    Hu, Z. -J
    Polar Research Institute of China, Shanghai 200136, China.
    James, M. K.
    Univ Leicester, Sch Phys & Astron, Planetary Sci Grp, Univ Rd, Leicester LE1 7RH, Leics, England..
    Juusola, L.
    Finnish Meteorol Inst FMI, Helsinki, Finland..
    Kauristie, K.
    Finnish Meteorol Inst FMI, Helsinki, Finland..
    Kronberg, E. A.
    Ludwig Maximilian Univ Munich LMU Munich, Dept Earth & Environm Sci Geophys, Theresienstr 41, D-80333 Munich, Germany..
    Lester, M.
    Univ Leicester, Sch Phys & Astron, Planetary Sci Grp, Univ Rd, Leicester LE1 7RH, Leics, England..
    Manuel, J.
    Canadian Space Agcy, Montreal, PQ, Canada..
    Matzka, J.
    GFZ German Res Ctr Geosci, Potsdam, Germany..
    McCrea, I.
    Rutherford Appleton Laboratory Space, Science Technology Facilities Council, Oxfordshire, UK.
    Miyoshi, Y.
    Nagoya Univ, Inst Space Earth Environm Res, Ctr Integrated Data Sci, Nagoya, Aichi 4648601, Japan..
    Rae, J.
    Northumbria Univ, Newcastle Upon Tyne NE1 8ST, Tyne & Wear, England..
    Ren, L.
    Chinese Acad Sci, Natl Space Sci Ctr, Beijing 100190, Peoples R China..
    Sigernes, F.
    Univ Ctr Svalbard, Arct Geophys, Longyearbyen, Norway..
    Spanswick, E.
    Department of Physics and Astronomy, University of Calgary, 2500 University Drive, Calgary, Alberta, Canada T2N 1N4.
    Sterne, K.
    Center for Space Plasma Physics, Space Science Institute, 4765 Walnut Street Suite B, Boulder, Colorado, 80301, USA.
    Steuwer, A.
    EISCAT, Kiruna, Sweden..
    Sun, T.
    Chinese Acad Sci, Natl Space Sci Ctr, Beijing 100190, Peoples R China..
    Walach, M. -T
    Space and Planetary Physics Group, Physics Department, Lancaster University, Lancaster, LA1 4YB, UK.
    Walsh, B.
    Boston Univ, Ctr Space Phys, Boston, MA USA..
    Wang, C.
    Chinese Acad Sci, Natl Space Sci Ctr, Beijing 100190, Peoples R China..
    Weygand, J.
    Univ Calif Los Angeles, Earth Planetary & Space Sci, Los Angeles, CA USA..
    Wild, J.
    Space and Planetary Physics Group, Physics Department, Lancaster University, Lancaster, LA1 4YB, UK.
    Yan, J.
    Chinese Acad Sci, Natl Space Sci Ctr, Beijing 100190, Peoples R China..
    Zhang, J.
    Chinese Acad Sci, Natl Space Sci Ctr, Beijing 100190, Peoples R China..
    Zhang, Q. -H
    Shandong Provincial Key Laboratory of Optical Astronomy;Solar-Terrestrial Environment, Institute of Space Sciences, Shandong University, Weihai Shandong 264209, China.
    Ground-based and additional science support for SMILE2024In: Earth and Planetary Physics, ISSN 2096-3955, Vol. 8, no 1, p. 275-298Article in journal (Refereed)
    Abstract [en]

    The joint European Space Agency and Chinese Academy of Sciences Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) mission will explore global dynamics of the magnetosphere under varying solar wind and interplanetary magnetic field conditions, and simultaneously monitor the auroral response of the Northern Hemisphere ionosphere. Combining these large-scale responses with medium and fine-scale measurements at a variety of cadences by additional ground-based and space-based instruments will enable a much greater scientific impact beyond the original goals of the SMILE mission. Here, we describe current community efforts to prepare for SMILE, and the benefits and context various experiments that have explicitly expressed support for SMILE can offer. A dedicated group of international scientists representing many different experiment types and geographical locations, the Ground-based and Additional Science Working Group, is facilitating these efforts. Preparations include constructing an online SMILE Data Fusion Facility, the discussion of particular or special modes for experiments such as coherent and incoherent scatter radar, and the consideration of particular observing strategies and spacecraft conjunctions. We anticipate growing interest and community engagement with the SMILE mission, and we welcome novel ideas and insights from the solar-terrestrial community.

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    FULLTEXT01
  • 131. Catapano, Filomena
    et al.
    Buchert, Stephan
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Qamili, Enkelejda
    Nilsson, Thomas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Bouffard, Jerome
    Siemes, Christian
    Coco, Igino
    D'Amicis, Raffaella
    Tøffner-Clausen, Lars
    Trenchi, Lorenzo
    Holmdahl Olsen, Poul Erik
    Stromme, Anja
    Swarm Langmuir probes' data quality validation and future improvements2022In: Geoscientific Instrumentation, Methods and Data Systems, ISSN 2193-0856, E-ISSN 2193-0864, Vol. 11, no 1, p. 149-162Article in journal (Refereed)
    Abstract [en]

    Swarm is the European Space Agency (ESA)'s first Earth observation constellation mission, which was launched in 2013 to study the geomagnetic field and its temporal evolution. Two Langmuir probes aboard each of the three Swarm satellites provide in situ measurements of plasma parameters, which contribute to the study of the ionospheric plasma dynamics. To maintain a high data quality for scientific and technical applications, the Swarm products are continuously monitored and validated via science-oriented diagnostics. This paper presents an overview of the data quality of the Swarm Langmuir probes' measurements. The data quality is assessed by analysing short and long data segments, where the latter are selected to be sufficiently long enough to consider the impact of the solar activity. Langmuir probe data have been validated through comparison with numerical models, other satellite missions, and ground observations. Based on the outcomes from quality control and validation activities conducted by ESA, as well as scientific analysis and feedback provided by the user community, the Swarm products are regularly upgraded. In this paper, we discuss the data quality improvements introduced with the latest baseline, and how the data quality is influenced by the solar cycle. In particular, plasma measurements are more accurate in day-side regions during high solar activity, while electron temperature measurements are more reliable during night side at middle and low latitudes during low solar activity. The main anomalies affecting the Langmuir probe measurements are described, as well as possible improvements in the derived plasma parameters to be implemented in future baselines.

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    fulltext
  • 132.
    Catapano, Filomena
    et al.
    Univ Paris Sud, Lab Phys Plasmas, CNRS, Ecole Polytech,Sorbonne Univ,Observ Paris, Paris, France.;Univ Calabria, Dipartimento Fis, Arcavacata Di Rende, Italy..
    Retino, Alessandro
    Univ Paris Sud, Lab Phys Plasmas, CNRS, Ecole Polytech,Sorbonne Univ,Observ Paris, Paris, France..
    Zimbardo, Gaetano
    Univ Calabria, Dipartimento Fis, Arcavacata Di Rende, Italy..
    Alexandrova, Alexandra
    Univ Paris Sud, Lab Phys Plasmas, CNRS, Ecole Polytech,Sorbonne Univ,Observ Paris, Paris, France..
    Cohen, Ian J.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Turner, Drew L.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Le Contel, Olivier
    Univ Paris Sud, Lab Phys Plasmas, CNRS, Ecole Polytech,Sorbonne Univ,Observ Paris, Paris, France..
    Cozzani, Giulia
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Perri, Silvia
    Univ Calabria, Dipartimento Fis, Arcavacata Di Rende, Italy..
    Greco, Antonella
    Univ Calabria, Dipartimento Fis, Arcavacata Di Rende, Italy..
    Breuillard, Hugo
    Univ Paris Sud, Lab Phys Plasmas, CNRS, Ecole Polytech,Sorbonne Univ,Observ Paris, Paris, France.;CNRS, Lab Phys & Chim Environm & Espace, Orleans, France..
    Delcourt, Dominique
    CNRS, Lab Phys & Chim Environm & Espace, Orleans, France..
    Mirioni, Laurent
    Univ Paris Sud, Lab Phys Plasmas, CNRS, Ecole Polytech,Sorbonne Univ,Observ Paris, 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.
    Giles, Barbara L.
    Goddard Space Flight Ctr, Greenbelt, MD USA..
    Mauk, Barry H.
    Johns Hopkins Univ, Appl Phys Lab, Laurel, MD USA..
    Fuselier, Stephen A.
    Southwest Res Inst, San Antonio, TX USA.;Univ Texas San Antonio, San Antonio, TX USA..
    Torbert, Roy B.
    Univ New Hampshire, Durham, NH 03824 USA..
    Russell, Christopher T.
    Univ Calif Los Angeles, Dept Earth & Space Sci, Los Angeles, CA 90024 USA..
    Lindqvist, Per A.
    Royal Inst Technol, Stockholm, Sweden..
    Ergun, Robert E.
    Univ Colorado, LASP, Boulder, CO 80309 USA..
    Moore, Thomas
    Goddard Space Flight Ctr, Greenbelt, MD USA..
    Burch, James L.
    Southwest Res Inst, San Antonio, TX USA..
    In Situ Evidence of Ion Acceleration between Consecutive Reconnection Jet Fronts2021In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 908, no 1, article id 73Article in journal (Refereed)
    Abstract [en]

    Processes driven by unsteady reconnection can efficiently accelerate particles in many astrophysical plasmas. An example is the reconnection jet fronts in an outflow region. We present evidence of suprathermal ion acceleration between two consecutive reconnection jet fronts observed by the Magnetospheric Multiscale mission in the terrestrial magnetotail. An earthward propagating jet is approached by a second faster jet. Between the jets, the thermal ions are mostly perpendicular to magnetic field, are trapped, and are gradually accelerated in the parallel direction up to 150 keV. Observations suggest that ions are predominantly accelerated by a Fermi-like mechanism in the contracting magnetic bottle formed between the two jet fronts. The ion acceleration mechanism is presumably efficient in other environments where jet fronts produced by variable rates of reconnection are common and where the interaction of multiple jet fronts can also develop a turbulent environment, e.g., in stellar and solar eruptions.

  • 133. 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.

  • 134.
    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.

  • 135.
    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.

  • 136.
    Chatain, A.
    et al.
    Univ Paris Saclay, UVSQ, CNRS, LATMOS, Guyancourt, France.;Sorbonne Univ, CNRS, Inst Polytech Paris, LPP,Ecole Polytech, Palaiseau, France..
    Wahlund, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Shebanits, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Imperial Coll London, South Kensington, England..
    Hadid, Lina Z
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Sorbonne Univ, CNRS, Inst Polytech Paris, LPP,Ecole Polytech, Palaiseau, France..
    Morooka, Michiko
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Edberg, Niklas J. T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Guaitella, O.
    Sorbonne Univ, CNRS, Inst Polytech Paris, LPP,Ecole Polytech, Palaiseau, France..
    Carrasco, N.
    Univ Paris Saclay, UVSQ, CNRS, LATMOS, Guyancourt, France..
    Re-Analysis of the Cassini RPWS/LP Data in Titan's Ionosphere: 1. Detection of Several Electron Populations2021In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 126, no 8, article id e2020JA028412Article in journal (Refereed)
    Abstract [en]

    Current models of Titan's ionosphere have difficulties in explaining the observed electron density and/or temperature. In order to get new insights, we re-analyzed the data taken in the ionosphere of Titan by the Cassini Langmuir probe (LP), part of the Radio and Plasma Wave Science (RPWS) instrument. This is the first of two papers that present the new analysis method (current paper) and statistics on the whole data set. We suggest that between two and four electron populations are necessary to fit the data. Each population is defined by a potential, an electron density and an electron temperature and is easily visualized by a distinct peak in the second derivative of the electron current, which is physically related to the electron energy distribution function (Druyvesteyn method). The detected populations vary with solar illumination and altitude. We suggest that the four electron populations are due to photo-ionization, magnetospheric particles, dusty plasma and electron emission from the probe boom, respectively.

  • 137.
    Chatain, A.
    et al.
    Univ Paris Saclay, UVSQ, CNRS, LATMOS, Guyancourt, France.;Sorbonne Univ, LPP, CNRS, Ecole Polytech,Inst Polytech Paris, Palaiseau, France..
    Wahlund, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Shebanits, Oleg
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Imperial Coll London, London, England..
    Hadid, Lina Z
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division. Sorbonne Univ, LPP, CNRS, Ecole Polytech,Inst Polytech Paris, Palaiseau, France..
    Morooka, Michiko
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Edberg, Niklas J. T.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Guaitella, O.
    Sorbonne Univ, LPP, CNRS, Ecole Polytech,Inst Polytech Paris, Palaiseau, France..
    Carrasco, N.
    Univ Paris Saclay, UVSQ, CNRS, LATMOS, Guyancourt, France..
    Re-Analysis of the Cassini RPWS/LP Data in Titan's Ionosphere: 2. Statistics on 57 Flybys2021In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 126, no 8, article id e2020JA028413Article in journal (Refereed)
    Abstract [en]

    The ionosphere of Titan hosts a complex ion chemistry leading to the formation of organic dust below 1,200 km. Current models cannot fully explain the observed electron temperature in this dusty environment. To achieve new insight, we have re-analyzed the data taken in the ionosphere of Titan by the Cassini Langmuir probe (LP), part of the Radio and Plasma Wave Science package. A first paper (Chatain et al., 2021) introduces the new analysis method and discusses the identification of four electron populations produced by different ionization mechanisms. In this second paper, we present a statistical study of the whole LP dataset below 1,200 km which gives clues on the origin of the four populations. One small population is attributed to photo- or secondary electrons emitted from the surface of the probe boom. A second population is systematically observed, at a constant density (similar to 500 cm(-3)), and is attributed to background thermalized electrons from the ionization process of precipitating particles from the surrounding magnetosphere. The two last populations increase in density with pressure, solar illumination and Extreme ultraviolet flux. The third population is observed with varying densities at all altitudes and solar zenith angles (SZA) except on the far nightside (SZA > similar to 140 degrees), with a maximum density of 2,700 cm(-3). It is therefore certainly related to the photo-ionization of the atmospheric molecules. Finally, a fourth population detected only on the dayside and below 1,200 km reaching up to 2000 cm(-3) could be photo- or thermo-emitted from dust grains.

  • 138. 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.

  • 139. 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.

  • 140. Chen, L. -J
    et al.
    Wang, S.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA;Univ Maryland, Dept Astron, College Pk, MD 20742 USA.
    Hesse, M.
    Univ Bergen, Dept Phys & Technol, Bergen, Norway.
    Ergun, R. E.
    Univ Colorado, Atmospher & Space Phys Lab, Campus Box 392, Boulder, CO 80309 USA.
    Moore, T.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Giles, B.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Bessho, N.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA;Univ Maryland, Dept Astron, College Pk, MD 20742 USA.
    Russell, C.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA USA.
    Burch, J.
    Southwest Res Inst, San Antonio, TX USA.
    Torbert, R. B.
    Southwest Res Inst, San Antonio, TX USA;Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA.
    Genestreti, K. J.
    Univ New Hampshire, Ctr Space Sci, Durham, NH 03824 USA.
    Paterson, W.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Pollock, C.
    Denali Sci, Healy, AK USA.
    Lavraud, B.
    Univ Toulouse UPS, Inst Rech Astrophys & Planetol, CNRS, CNES, Toulouse, France.
    Le Contel, O.
    Univ Paris Sud, Lab Phys Plasmas UMR7648, Ecole Polytech, CNRS,Sorbonne Univ,Observ Paris, Paris, France.
    Strangeway, R.
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA USA.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Lindqvist, P. -A
    Electron Diffusion Regions in Magnetotail Reconnection Under Varying Guide Fields2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 12, p. 6230-6238Article in journal (Refereed)
    Abstract [en]

    Kinetic structures of electron diffusion regions (EDRs) under finite guide fields in magnetotail reconnection are reported. The EDRs with guide fields 0.14-0.5 (in unit of the reconnecting component) are detected by the Magnetospheric Multiscale spacecraft. The key new features include the following: (1) cold inflowing electrons accelerated along the guide field and demagnetized at the magnetic field minimum while remaining a coherent population with a low perpendicular temperature, (2) wave fluctuations generating strong perpendicular electron flows followed by alternating parallel flows inside the reconnecting current sheet under an intermediate guide field, and (3) gyrophase bunched electrons with high parallel speeds leaving the X-line region. The normalized reconnection rates for the three EDRs range from 0.05 to 0.3. The measurements reveal that finite guide fields introduce new mechanisms to break the electron frozen-in condition. Plain Language Summary Magnetic reconnection plays a crucial role in the dynamics of the terrestrial magnetotail. For reconnection to occur, the plasma must decouple from the magnetic field. The bounce motion of particles in the magnetotail current sheet is regarded as a key to this decoupling for cases when the current sheet has no magnetic field along the direction of the current. This paper reports that while bounce motion remains relevant when a finite magnetic field is present along the current, new mechanisms to decouple electrons from the magnetic field are introduced, and new open questions unfold. The observations are based on measurements from the Magnetospheric Multiscale mission. The mission's unprecedented high cadence electron data make possible the revelation of the new mechanisms. The results reported in this paper expand the frontiers of our knowledge on magnetotail reconnection and have major implications on the fundamental physics of magnetic reconnection in all plasma systems where binary collisions are not effective, including solar, astrophysical, and laboratory plasmas. Rapid dissemination of the results will set the ground for advances in magnetic reconnection research.

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  • 141. Chen, L. -J
    et al.
    Wang, S.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA;Univ Maryland, Dept Astron, College Pk, MD 20747 USA.
    Wilson, L. B. , I I I
    Schwartz, S.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80305 USA.
    Bessho, N.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA;Univ Maryland, Dept Astron, College Pk, MD 20747 USA.
    Moore, T.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Gershman, D.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Giles, B.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Malaspina, D.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80305 USA.
    Wilder, F. D.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80305 USA.
    Ergun, R. E.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80305 USA.
    Hesse, M.
    Univ Bergen, N-5020 Bergen, Norway.
    Lai, H.
    Univ Calif Los Angeles, Los Angeles, CA 90095 USA.
    Russell, C.
    Univ Calif Los Angeles, Los Angeles, CA 90095 USA.
    Strangeway, R.
    Univ Calif Los Angeles, Los Angeles, CA 90095 USA.
    Torbert, R. B.
    Southwest Res Inst, San Antonio, TX 78238 USA.
    Vinas, A. F.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Burch, J.
    Southwest Res Inst, San Antonio, TX 78238 USA.
    Lee, S.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Pollock, C.
    Denali Sci, Healy, AK 99743 USA.
    Dorelli, J.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Paterson, W.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.
    Ahmadi, N.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80305 USA.
    Goodrich, K.
    Univ Colorado, Lab Atmospher & Space Phys, Boulder, CO 80305 USA.
    Lavraud, B.
    Univ Toulouse UPS, Inst Rech Astrophys & Planetol, CNRS, CNES, F-31028 Toulouse 4, France.
    Le Contel, O.
    Univ Paris Sud, Observ Paris, Lab Phys Plasmas, UMR7648,CNRS,Ecole Polytech,Sorbonne Univ, F-91128 Palaiseau, France.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Lindqvist, P. -A
    Boardsen, S.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA;Univ Maryland, Dept Astron, College Pk, MD 20747 USA.
    Wei, H.
    Univ Calif Los Angeles, Los Angeles, CA 90095 USA.
    Le, A.
    Los Alamos Natl Lab, Los Alamos, NM 87545 USA.
    Avanov, L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA;Univ Maryland, Dept Astron, College Pk, MD 20747 USA.
    Electron Bulk Acceleration and Thermalization at Earth's Quasiperpendicular Bow Shock2018In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 120, no 22, article id 225101Article in journal (Refereed)
    Abstract [en]

    Electron heating at Earth's quasiperpendicular bow shock has been surmised to be due to the combined effects of a quasistatic electric potential and scattering through wave-particle interaction. Here we report the observation of electron distribution functions indicating a new electron heating process occurring at the leading edge of the shock front. Incident solar wind electrons are accelerated parallel to the magnetic field toward downstream, reaching an electron-ion relative drift speed exceeding the electron thermal speed. The bulk acceleration is associated with an electric field pulse embedded in a whistler-mode wave. The high electron-ion relative drift is relaxed primarily through a nonlinear current-driven instability. The relaxed distributions contain a beam traveling toward the shock as a remnant of the accelerated electrons. Similar distribution functions prevail throughout the shock transition layer, suggesting that the observed acceleration and thermalization is essential to the cross-shock electron heating.

  • 142. Chen, Li-Jen
    et al.
    Bessho, N.
    Lefebvre, B.
    Vaith, H.
    Fazakerley, A.
    Bhattacharjee, A.
    Puhl-Quinn, P. A.
    Runov, A.
    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.
    Georgescu, E.
    Torbert, R.
    Evidence of an extended electron current sheet and its neighboring magnetic island during magnetotail reconnection2008In: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 113, no A12, p. A12213-Article in journal (Refereed)
    Abstract [en]

    We have identified a spatially extended electron current sheet (ECS) and its adjacent magnetic island during a magnetotail reconnection event with no appreciable guide field. This finding is based on data from the four Cluster spacecraft and is enabled by detailed maps of electron distribution functions and DC electric fields within the diffusion region. The maps are developed using two-dimensional particle-in-cell simulations with a mass ratio m(i)/m(e) = 800. One spacecraft crossed the ECS earthward of the reconnection null and, together with the other three spacecraft, registered the following properties: (1) The ECS is colocated with a layer of bipolar electric fields normal to the ECS, pointing toward the ECS, and with a half width less than 8 electron skin depths. (2) In the inflow region up to the ECS and separatrices, electrons have a temperature anisotropy (Te-parallel to/Te-perpendicular to > 1), and the anisotropy increases toward the ECS. (3) Within about 1 ion skin depth (d(i)) above and below the ECS, the electron density decreases toward the ECS by a factor of 3-4, reaching a minimum at edges of the ECS, and has a local distinct maximum at the ECS center. (4) A di-scale magnetic island is attached to the ECS, separating it from another reconnection layer. Our simulations established that the electric field normal to the ECS is due to charge imbalance and is of the ECS scale, and ions exhibit electron-scale structures in response to this electric field.

  • 143. Chen, Li-Jen
    et al.
    Bessho, Naoki
    Lefebvre, Bertrand
    Vaith, Hans
    Asnes, Arne
    Santolik, Ondrej
    Fazakerley, Andrew
    Puhl-Quinn, Pamela
    Bhattacharjee, Amitava
    Khotyaintsev, Yuri
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Daly, Patrick
    Torbert, Roy
    Multispacecraft observations of the electron current sheet, neighboring magnetic islands, and electron acceleration during magnetotail reconnection2009In: Physics of Plasmas, ISSN 1070-664X, E-ISSN 1089-7674, Vol. 16, no 5, p. 056501-Article in journal (Refereed)
    Abstract [en]

    Open questions concerning structures and dynamics of diffusion regions and electron acceleration in collisionless magnetic reconnection are addressed based on data from the four-spacecraft mission Cluster and particle-in-cell simulations. Using time series of electron distribution functions measured by the four spacecraft, distinct electron regions around a reconnection layer are mapped out to set the framework for studying diffusion regions. A spatially extended electron current sheet (ecs), a series of magnetic islands, and bursts of energetic electrons within islands are identified during magnetotail reconnection with no appreciable guide field. The ecs is collocated with a layer of electron-scale electric fields normal to the ecs and pointing toward the ecs center plane. Both the observed electron and ion densities vary by more than a factor of 2 within one ion skin depth north and south of the ecs, and from the ecs into magnetic islands. Within each of the identified islands, there is a burst of suprathermal electrons whose fluxes peak at density compression sites [L.-J. Chen , Nat. Phys. 4, 19 (2008)] and whose energy spectra exhibit power laws with indices ranging from 6 to 7.3. These results indicate that the in-plane electric field normal to the ecs can be of the electron scale at certain phases of reconnection, electrons and ions are highly compressible within the ion diffusion region, and for reconnection involving magnetic islands, primary electron acceleration occurs within the islands.

  • 144. Chen, Li-Jen
    et al.
    Bhattacharjee, A.
    Puhl-Quinn, P. A.
    Yang, H.
    Bessho, N.
    Imada, S.
    Muehlbachler, S.
    Daly, P. W.
    Lefebvre, B.
    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.
    Fazakerley, A.
    Georgescu, E.
    Observation of energetic electrons within magnetic islands2008In: Nature Physics, ISSN 1745-2473, E-ISSN 1745-2481, Vol. 4, no 1, p. 19-23Article in journal (Refereed)
    Abstract [en]

    Magnetic reconnection is the underlying process that releases impulsively an enormous amount of magnetic energy(1) in solar flares(2,3), flares on strongly magnetized neutron stars(4) and substorms in the Earth's magnetosphere(5). Studies of energy release during solar flares, in particular, indicate that up to 50% of the released energy is carried by accelerated 20-100 keV suprathermal electrons(6-8). How so many electrons can gain so much energy during reconnection has been a long-standing question. A recent theoretical study suggests that volume-filling contracting magnetic islands formed during reconnection can produce a large number of energetic electrons(9). Here we report the first evidence of the link between energetic electrons and magnetic islands during reconnection in the Earth's magnetosphere. The results indicate that energetic electron fluxes peak at sites of compressed density within islands, which imposes a new constraint on theories of electron acceleration.

  • 145.
    Chen, Li-Jen
    et al.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Hesse, Michael
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Wang, Shan
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Gershman, Daniel
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Ergun, Robert
    Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA..
    Pollock, Craig
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Torbert, Roy
    Univ New Hampshire, Dept Phys, Durham, NH 03824 USA..
    Bessho, Naoki
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Daughton, William
    Los Alamos Natl Lab, Los Alamos, NM USA..
    Dorelli, John
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Giles, Barbara
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Strangeway, Robert
    Univ Calif Los Angeles, Dept Earth Planetary & Space Sci, Los Angeles, CA USA..
    Russell, Christopher
    Univ Calif Los Angeles, Dept 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.
    Burch, Jim
    Southwest Res Inst, San Antonio, TX USA..
    Moore, Thomas
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA..
    Lavraud, Benoit
    Univ Toulouse, Inst Rech Astrophys & Plantol, Toulouse, France.;CNRS, Toulouse, France..
    Phan, Tai
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Avanov, Levon
    NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA.;Univ Maryland, Dept Astron, College Pk, MD 20742 USA..
    Electron energization and mixing observed by MMS in the vicinity of an electron diffusion region during magnetopause reconnection2016In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 43, no 12, p. 6036-6043Article in journal (Refereed)
    Abstract [en]

    Measurements from the Magnetospheric Multiscale (MMS) mission are reported to show distinct features of electron energization and mixing in the diffusion region of the terrestrial magnetopause reconnection. At the ion jet and magnetic field reversals, distribution functions exhibiting signatures of accelerated meandering electrons are observed at an electron out-of-plane flow peak. The meandering signatures manifested as triangular and crescent structures are established features of the electron diffusion region (EDR). Effects of meandering electrons on the electric field normal to the reconnection layer are detected. Parallel acceleration and mixing of the inflowing electrons with exhaust electrons shape the exhaust flow pattern. In the EDR vicinity, the measured distribution functions indicate that locally, the electron energization and mixing physics is captured by two-dimensional reconnection, yet to account for the simultaneous four-point measurements, translational invariant in the third dimension must be violated on the ion-skin-depth scale.

  • 146.
    Chen, L-J
    et al.
    NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA..
    Wang, S.
    NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA.;Univ Maryland, College Pk, MD 20747 USA..
    Le Contel, O.
    Univ Paris Sud, Sorbonne Univ, Observ Paris, CNRS,Ecole Polytech, F-91128 Paris, France..
    Rager, A.
    NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA..
    Hesse, M.
    Univ Bergen, N-5020 Bergen, Norway..
    Drake, J.
    Univ Maryland, College Pk, MD 20747 USA..
    Dorelli, J.
    NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA..
    Ng, J.
    NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA.;Univ Maryland, College Pk, MD 20747 USA..
    Bessho, N.
    NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA.;Univ Maryland, College Pk, MD 20747 USA..
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Wilson, Lynn B., III
    NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA..
    Moore, T.
    NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA..
    Giles, B.
    NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA..
    Paterson, W.
    NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA..
    Lavraud, B.
    Univ Toulouse UPS, CNRS, CNES, Inst Rech Astrophys & Planetol, F-31027 Toulouse 4, France..
    Genestreti, K.
    Univ New Hampshire, Durham, NH 03824 USA..
    Nakamura, R.
    Austrian Acad Sci, Space Res Inst, A-8042 Graz, Austria..
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Ergun, R. E.
    Univ Colorado, Boulder, CO 80305 USA..
    Torbert, R. B.
    Univ New Hampshire, Durham, NH 03824 USA..
    Burch, J.
    Southwest Res Inst, San Antonio, TX 78238 USA..
    Pollock, C.
    Denali Sci, Healy, AK 99743 USA..
    Russell, C. T.
    Univ Calif Los Angeles, Los Angeles, CA 90095 USA..
    Lindqvist, P-A
    KTH Royal Inst Technol, SE-11428 Stockholm, Sweden..
    Avanov, L.
    NASA, Goddard Space Flight Ctr, Code 916, Greenbelt, MD 20771 USA.;Univ Maryland, College Pk, MD 20747 USA..
    Lower-Hybrid Drift Waves Driving Electron Nongyrotropic Heating and Vortical Flows in a Magnetic Reconnection Layer2020In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 125, no 2, article id 025103Article in journal (Refereed)
    Abstract [en]

    We report measurements of lower-hybrid drift waves driving electron heating and vortical flows in an electron-scale reconnection layer under a guide field. Electrons accelerated by the electrostatic potential of the waves exhibit perpendicular and nongyrotropic heating. The vortical flows generate magnetic field perturbations comparable to the guide field magnitude. The measurements reveal a new regime of electron-wave interaction and how this interaction modifies the electron dynamics in the reconnection layer.

  • 147.
    Chen, Z. Z.
    et al.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China.
    Fu, H. S.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China.
    Liu, C. M.
    Beihang Univ, Sch Space & Environm, Beijing, Peoples R China.
    Wang, T. Y.
    STFC, RAL Space, Didcot, Oxon, England.
    Ergun, R. E.
    Univ Colorado, Dept Astrophys & Planetary Sci, Boulder, CO 80309 USA.
    Cozzani, G.
    UPMC, Ecole Polytech, CNRS, Lab Phys Plasmas, Palaiseau, France.
    Huang, S. Y.
    Wuhan Univ, Sch Elect Informat, Wuhan, Hubei, Peoples R China.
    Khotyaintsev, Yuri V.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Le Contel, O.
    UPMC, Ecole Polytech, CNRS, Lab Phys Plasmas, Palaiseau, France.
    Giles, B. L.
    NASA, Goddard Space Flight Ctr, Greenbelt, MD USA.
    Burch, J. L.
    Southwest Res Inst, San Antonio, TX USA.
    Electron-Driven Dissipation in a Tailward Flow Burst2019In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 46, no 11, p. 5698-5706Article in journal (Refereed)
    Abstract [en]

    Traditionally, the magnetotail flow burst outside the diffusion region is known to carry ions and electrons together (V-i = V-e), with the frozen-in condition well satisfied (E + V-e x B = 0). Such picture, however, may not be true, based on our analyses of the high-resolution MMS (Magnetospheric Multiscale mission) data. We find that inside the flow burst the electrons and ions can be decoupled (V-e not equal V-i), with the electron speed 5 times larger than the ion speed. Such super-Alfvenic electron jet, having scale of 10 d(i) (ion inertial length) in X-GSM direction, is associated with electron demagnetization (E + V-e x B not equal 0), electron agyrotropy (crescent distribution), and O-line magnetic topology but not associated with the flow reversal and X-line topology; it can cause strong energy dissipation and electron heating. We quantitatively analyze the dissipation and find that it is primarily attributed to lower hybrid drift waves. These results emphasize the non-MHD (magnetohydrodynamics) behaviors of magnetotail flow bursts and the role of lower hybrid drift waves in dissipating energies.

  • 148.
    Chiappetta, Federica
    et al.
    Univ Calabria, Dipartimento Fis, Ponte P Bucci Cubo 31C, Arcavacata Di Rende, CS, Italy..
    Yordanova, Emiliya
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Voros, Zoltan
    Space Res Inst, Schmiedlstr 6, Graz, Austria.;HUN REN, Inst Earth Phys & Space Sci, Sopron, Hungary..
    Lepreti, Fabio
    Univ Calabria, Dipartimento Fis, Ponte P Bucci Cubo 31C, Arcavacata Di Rende, CS, Italy.;Ist Nazl Astrofis INAF, Direz Sci, Rome, Italy..
    Carbone, Vincenzo
    Univ Calabria, Dipartimento Fis, Ponte P Bucci Cubo 31C, Arcavacata Di Rende, CS, Italy.;Ist Nazl Astrofis INAF, Direz Sci, Rome, Italy..
    Energy Conversion through a Fluctuation-Dissipation Relation at Kinetic Scales in the Earth's Magnetosheath2023In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 957, no 2, article id 98Article in journal (Refereed)
    Abstract [en]

    Low-frequency fluctuations in the interplanetary medium represent a turbulent environment where universal scaling behavior, generated by an energy cascade, has been investigated. On the contrary, in some regions, for example, the magnetosheath, universality of statistics of fluctuations is lost. However, at kinetic scales where energy must be dissipated, the energy conversion seems to be realized through a mechanism similar to the free solar wind. Here we propose a Langevin model for magnetic fluctuations at kinetic scales, showing that the resulting fluctuation-dissipation relation is capable of describing the gross features of the spectral observations at kinetic scales in the magnetosheath. The fluctuation-dissipation relation regulates the energy conversion by imposing a relationship between fluctuations and dissipation, which at high frequencies are active at the same time in the same range of scales and represent two ingredients of the same physical process.

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  • 149.
    Chust, T.
    et al.
    Sorbonne Univ, Univ Paris Saclay, Observ Paris, Ecole Polytech,LPP,CNRS, Paris, France..
    Kretzschmar, M.
    Univ Orleans, CNRS, LPC2E, 3A Ave Rech Sci, Orleans, France..
    Graham, Daniel B.
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Le Contel, O.
    Sorbonne Univ, Univ Paris Saclay, Observ Paris, Ecole Polytech,LPP,CNRS, Paris, France..
    Retino, A.
    Sorbonne Univ, Univ Paris Saclay, Observ Paris, Ecole Polytech,LPP,CNRS, Paris, France..
    Alexandrova, A.
    Sorbonne Univ, Univ Paris Saclay, Observ Paris, Ecole Polytech,LPP,CNRS, Paris, France..
    Berthomier, M.
    Sorbonne Univ, Univ Paris Saclay, Observ Paris, Ecole Polytech,LPP,CNRS, Paris, France..
    Hadid, L. Z.
    Sorbonne Univ, Univ Paris Saclay, Observ Paris, Ecole Polytech,LPP,CNRS, Paris, France..
    Sahraoui, F.
    Sorbonne Univ, Univ Paris Saclay, Observ Paris, Ecole Polytech,LPP,CNRS, Paris, France..
    Jeandet, A.
    Sorbonne Univ, Univ Paris Saclay, Observ Paris, Ecole Polytech,LPP,CNRS, Paris, France..
    Leroy, P.
    Sorbonne Univ, Univ Paris Saclay, Observ Paris, Ecole Polytech,LPP,CNRS, Paris, France..
    Pellion, J-C
    Sorbonne Univ, Univ Paris Saclay, Observ Paris, Ecole Polytech,LPP,CNRS, Paris, France..
    Bouzid, V
    Sorbonne Univ, Univ Paris Saclay, Observ Paris, Ecole Polytech,LPP,CNRS, Paris, France..
    Katra, B.
    Sorbonne Univ, Univ Paris Saclay, Observ Paris, Ecole Polytech,LPP,CNRS, Paris, France..
    Piberne, R.
    Sorbonne Univ, Univ Paris Saclay, Observ Paris, Ecole Polytech,LPP,CNRS, Paris, France..
    Khotyaintsev, Yuri V.
    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. Royal Inst Technol, Sch Elect Engn & Comp Sci, Dept Space & Plasma Phys, Stockholm, Sweden..
    Krasnoselskikh, V
    Univ Orleans, CNRS, LPC2E, 3A Ave Rech Sci, Orleans, France..
    Soucek, J.
    Czech Acad Sci, Dept Space Phys, Inst Atmospher Phys, Prague, Czech Republic..
    Santolik, O.
    Czech Acad Sci, Dept Space Phys, Inst Atmospher Phys, Prague, Czech Republic.;Charles Univ Prague, Fac Math & Phys, Prague, Czech Republic..
    Lorfevre, E.
    CNES, 18 Ave Edouard Belin, F-31400 Toulouse, France..
    Plettemeier, D.
    Tech Univ Dresden, Wurzburger Str 35, D-01187 Dresden, Germany..
    Steller, M.
    Austrian Acad Sci, Space Res Inst, Graz, Austria..
    Stverak, S.
    Czech Acad Sci, Astron Inst, Prague, Czech Republic..
    Vecchio, A.
    Czech Acad Sci, Astron Inst, Prague, Czech Republic.;Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA..
    Maksimovic, M.
    Univ PSL, Sorbonne Univ, Univ Paris, Observ Paris,LESIA,CNRS, Meudon, France.;Radboud Univ Nijmegen, Dept Astrophys, Radboud Radio Lab, Nijmegen, Netherlands..
    Bale, S. D.
    Univ PSL, Sorbonne Univ, Univ Paris, Observ Paris,LESIA,CNRS, Meudon, France..
    Horbury, T. S.
    Univ Calif Berkeley, Space Sci Lab, Berkeley, CA 94720 USA.;Univ Calif Berkeley, Phys Dept, Berkeley, CA USA.;Stellar Sci, Berkeley, CA USA..
    O'Brien, H.
    Imperial Coll, Dept Phys, London SW7 2AZ, England..
    Evans, V
    Imperial Coll, Dept Phys, London SW7 2AZ, England..
    Angelini, V
    Imperial Coll, Dept Phys, London SW7 2AZ, England..
    Observations of whistler mode waves by Solar Orbiter's RPW Low Frequency Receiver (LFR): In-flight performance and first results2021In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 656, article id A17Article in journal (Refereed)
    Abstract [en]

    Context. The Radio and Plasma Waves (RPW) instrument is one of the four in situ instruments of the ESA/NASA Solar Orbiter mission, which was successfully launched on February 10, 2020. The Low Frequency Receiver (LFR) is one of its subsystems, designed to characterize the low frequency electric (quasi-DC - 10 kHz) and magnetic (similar to 1 Hz-10 kHz) fields that develop, propagate, interact, and dissipate in the solar wind plasma. Combined with observations of the particles and the DC magnetic field, LFR measurements will help to improve the understanding of the heating and acceleration processes at work during solar wind expansion.

    Aims. The capability of LFR to observe and analyze a variety of low frequency plasma waves can be demontrated by taking advantage of whistler mode wave observations made just after the near-Earth commissioning phase of Solar Orbiter. In particular, this is related to its capability of measuring the wave normal vector, the phase velocity, and the Poynting vector for determining the propagation characteristics of the waves.

    Methods. Several case studies of whistler mode waves are presented, using all possible LFR onboard digital processing products, waveforms, spectral matrices, and basic wave parameters.

    Results. Here, we show that whistler mode waves can be very properly identified and characterized, along with their Doppler-shifted frequency, based on the waveform capture as well as on the LFR onboard spectral analysis.

    Conclusions. Despite the fact that calibrations of the electric and magnetic data still require some improvement, these first whistler observations show a good overall consistency between the RPW LFR data, indicating that many science results on these waves, as well as on other plasma waves, can be obtained by Solar Orbiter in the solar wind.

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    FULLTEXT01
  • 150. Coates, A. J.
    et al.
    Wahlund, Jan-Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Ågren, Karin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Edberg, Niklas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Swedish Institute of Space Physics, Uppsala Division.
    Cui, J.
    Wellbrock, A.
    Szego, K.
    Recent Results from Titan's Ionosphere2011In: Space Science Reviews, ISSN 0038-6308, E-ISSN 1572-9672, Vol. 162, no 1-4, p. 85-111Article, review/survey (Refereed)
    Abstract [en]

    Titan has the most significant atmosphere of any moon in the solar system, with a pressure at the surface larger than the Earth's. It also has a significant ionosphere, which is usually immersed in Saturn's magnetosphere. Occasionally it exits into Saturn's magnetosheath. In this paper we review several recent advances in our understanding of Titan's ionosphere, and present some comparisons with the other unmagnetized objects Mars and Venus. We present aspects of the ionospheric structure, chemistry, electrodynamic coupling and transport processes. We also review observations of ionospheric photoelectrons at Titan, Mars and Venus. Where appropriate, we mention the effects on ionospheric escape.

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