1
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Bale SD, Drake JF, McManus MD, Desai MI, Badman ST, Larson DE, Swisdak M, Horbury TS, Raouafi NE, Phan T, Velli M, McComas DJ, Cohen CMS, Mitchell D, Panasenco O, Kasper JC. Interchange reconnection as the source of the fast solar wind within coronal holes. Nature 2023; 618:252-256. [PMID: 37286648 DOI: 10.1038/s41586-023-05955-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 03/14/2023] [Indexed: 06/09/2023]
Abstract
The fast solar wind that fills the heliosphere originates from deep within regions of open magnetic field on the Sun called 'coronal holes'. The energy source responsible for accelerating the plasma is widely debated; however, there is evidence that it is ultimately magnetic in nature, with candidate mechanisms including wave heating1,2 and interchange reconnection3-5. The coronal magnetic field near the solar surface is structured on scales associated with 'supergranulation' convection cells, whereby descending flows create intense fields. The energy density in these 'network' magnetic field bundles is a candidate energy source for the wind. Here we report measurements of fast solar wind streams from the Parker Solar Probe (PSP) spacecraft6 that provide strong evidence for the interchange reconnection mechanism. We show that the supergranulation structure at the coronal base remains imprinted in the near-Sun solar wind, resulting in asymmetric patches of magnetic 'switchbacks'7,8 and bursty wind streams with power-law-like energetic ion spectra to beyond 100 keV. Computer simulations of interchange reconnection support key features of the observations, including the ion spectra. Important characteristics of interchange reconnection in the low corona are inferred from the data, including that the reconnection is collisionless and that the energy release rate is sufficient to power the fast wind. In this scenario, magnetic reconnection is continuous and the wind is driven by both the resulting plasma pressure and the radial Alfvénic flow bursts.
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Affiliation(s)
- S D Bale
- Physics Department, University of California, Berkeley, CA, USA.
- Space Sciences Laboratory, University of California, Berkeley, CA, USA.
| | - J F Drake
- Department of Physics, the Institute for Physical Science and Technology and the Joint Space Institute, University of Maryland, College Park, MD, USA
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD, USA
| | - M D McManus
- Physics Department, University of California, Berkeley, CA, USA
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - M I Desai
- Southwest Research Institute, San Antonio, TX, USA
| | - S T Badman
- Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA
| | - D E Larson
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - M Swisdak
- Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, MD, USA
| | - T S Horbury
- The Blackett Laboratory, Imperial College London, London, UK
| | - N E Raouafi
- Johns Hopkins Applied Physics Laboratory, Laurel, MD, USA
| | - T Phan
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - M Velli
- Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, CA, USA
- International Space Science Institute, Bern, Switzerland
| | - D J McComas
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ, USA
| | - C M S Cohen
- California Institute of Technology, Pasadena, CA, USA
| | - D Mitchell
- Johns Hopkins Applied Physics Laboratory, Laurel, MD, USA
| | - O Panasenco
- Advanced Heliophysics Inc., Los Angeles, CA, USA
| | - J C Kasper
- BWX Technologies, Inc., Washington, DC, USA
- Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI, USA
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2
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Persson M, Aizawa S, André N, Barabash S, Saito Y, Harada Y, Heyner D, Orsini S, Fedorov A, Mazelle C, Futaana Y, Hadid LZ, Volwerk M, Collinson G, Sanchez-Cano B, Barthe A, Penou E, Yokota S, Génot V, Sauvaud JA, Delcourt D, Fraenz M, Modolo R, Milillo A, Auster HU, Richter I, Mieth JZD, Louarn P, Owen CJ, Horbury TS, Asamura K, Matsuda S, Nilsson H, Wieser M, Alberti T, Varsani A, Mangano V, Mura A, Lichtenegger H, Laky G, Jeszenszky H, Masunaga K, Signoles C, Rojo M, Murakami G. BepiColombo mission confirms stagnation region of Venus and reveals its large extent. Nat Commun 2022; 13:7743. [PMID: 36522338 PMCID: PMC9755131 DOI: 10.1038/s41467-022-35061-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 11/16/2022] [Indexed: 12/23/2022] Open
Abstract
The second Venus flyby of the BepiColombo mission offer a unique opportunity to make a complete tour of one of the few gas-dynamics dominated interaction regions between the supersonic solar wind and a Solar System object. The spacecraft pass through the full Venusian magnetosheath following the plasma streamlines, and cross the subsolar stagnation region during very stable solar wind conditions as observed upstream by the neighboring Solar Orbiter mission. These rare multipoint synergistic observations and stable conditions experimentally confirm what was previously predicted for the barely-explored stagnation region close to solar minimum. Here, we show that this region has a large extend, up to an altitude of 1900 km, and the estimated low energy transfer near the subsolar point confirm that the atmosphere of Venus, despite being non-magnetized and less conductive due to lower ultraviolet flux at solar minimum, is capable of withstanding the solar wind under low dynamic pressure.
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Affiliation(s)
- M. Persson
- grid.15781.3a0000 0001 0723 035XInstitut de Recherche en Astrophysique et Planétologie, Centre National de la Recherche Scientifique, Centre National d’Etudes Spatiales, Université Paul Sabatier—Toulouse III, Toulouse, France
| | - S. Aizawa
- grid.15781.3a0000 0001 0723 035XInstitut de Recherche en Astrophysique et Planétologie, Centre National de la Recherche Scientifique, Centre National d’Etudes Spatiales, Université Paul Sabatier—Toulouse III, Toulouse, France
| | - N. André
- grid.15781.3a0000 0001 0723 035XInstitut de Recherche en Astrophysique et Planétologie, Centre National de la Recherche Scientifique, Centre National d’Etudes Spatiales, Université Paul Sabatier—Toulouse III, Toulouse, France
| | - S. Barabash
- grid.425140.60000 0001 0706 1867Swedish Institute of Space Physics, Kiruna, Sweden
| | - Y. Saito
- grid.62167.340000 0001 2220 7916Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Kyoto, Japan
| | - Y. Harada
- grid.258799.80000 0004 0372 2033Department of Geophysics, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - D. Heyner
- grid.6738.a0000 0001 1090 0254Institute for Geophysics and Extraterrestrial Physics, Technische Universität Braunschweig, Braunschweig, Germany
| | - S. Orsini
- grid.4293.c0000 0004 1792 8585Institute of Space Astrophysics and Planetology, Istituto Nazionale di Astrofisica, Rome, Italy
| | - A. Fedorov
- grid.15781.3a0000 0001 0723 035XInstitut de Recherche en Astrophysique et Planétologie, Centre National de la Recherche Scientifique, Centre National d’Etudes Spatiales, Université Paul Sabatier—Toulouse III, Toulouse, France
| | - C. Mazelle
- grid.15781.3a0000 0001 0723 035XInstitut de Recherche en Astrophysique et Planétologie, Centre National de la Recherche Scientifique, Centre National d’Etudes Spatiales, Université Paul Sabatier—Toulouse III, Toulouse, France
| | - Y. Futaana
- grid.425140.60000 0001 0706 1867Swedish Institute of Space Physics, Kiruna, Sweden
| | - L. Z. Hadid
- grid.508893.fLaboratoire de Physique des Plasmas (LPP), Centre National de la Recherche Scientifique, Observatoire de Paris, Sorbonne Université, Université Paris Saclay, École Polytechnique, Institut Polytechnique de Paris, Paris, France
| | - M. Volwerk
- grid.4299.60000 0001 2169 3852Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - G. Collinson
- grid.133275.10000 0004 0637 6666National Aeronautic and Space Administration, Goddard Space Flight Center, Greenbelt, MD USA
| | - B. Sanchez-Cano
- grid.9918.90000 0004 1936 8411School of Physics and Astronomy, University of Leicester, Leicester, UK
| | - A. Barthe
- grid.15781.3a0000 0001 0723 035XInstitut de Recherche en Astrophysique et Planétologie, Centre National de la Recherche Scientifique, Centre National d’Etudes Spatiales, Université Paul Sabatier—Toulouse III, Toulouse, France
| | - E. Penou
- grid.15781.3a0000 0001 0723 035XInstitut de Recherche en Astrophysique et Planétologie, Centre National de la Recherche Scientifique, Centre National d’Etudes Spatiales, Université Paul Sabatier—Toulouse III, Toulouse, France
| | - S. Yokota
- grid.136593.b0000 0004 0373 3971Department of Earth and Space Science, Graduate School of Science, Osaka University, Osaka, Japan
| | - V. Génot
- grid.15781.3a0000 0001 0723 035XInstitut de Recherche en Astrophysique et Planétologie, Centre National de la Recherche Scientifique, Centre National d’Etudes Spatiales, Université Paul Sabatier—Toulouse III, Toulouse, France
| | - J. A. Sauvaud
- grid.15781.3a0000 0001 0723 035XInstitut de Recherche en Astrophysique et Planétologie, Centre National de la Recherche Scientifique, Centre National d’Etudes Spatiales, Université Paul Sabatier—Toulouse III, Toulouse, France
| | - D. Delcourt
- grid.508893.fLaboratoire de Physique des Plasmas (LPP), Centre National de la Recherche Scientifique, Observatoire de Paris, Sorbonne Université, Université Paris Saclay, École Polytechnique, Institut Polytechnique de Paris, Paris, France
| | - M. Fraenz
- grid.435826.e0000 0001 2284 9011Max-Planck-Institute for Solar System Research, Göttingen, Germany
| | - R. Modolo
- Laboratoire Atmosphères, Milieux, Observations Spatiales, Institut Pierre Simon Laplace, Université Versailles Saint Quentin en Yvelines, Université Paris-Saclay, Université Pierre Marie Curie, Centre National de la Recherche Scientifique, Guyancourt, France
| | - A. Milillo
- grid.4293.c0000 0004 1792 8585Institute of Space Astrophysics and Planetology, Istituto Nazionale di Astrofisica, Rome, Italy
| | - H.-U. Auster
- grid.6738.a0000 0001 1090 0254Institute for Geophysics and Extraterrestrial Physics, Technische Universität Braunschweig, Braunschweig, Germany
| | - I. Richter
- grid.6738.a0000 0001 1090 0254Institute for Geophysics and Extraterrestrial Physics, Technische Universität Braunschweig, Braunschweig, Germany
| | - J. Z. D. Mieth
- grid.6738.a0000 0001 1090 0254Institute for Geophysics and Extraterrestrial Physics, Technische Universität Braunschweig, Braunschweig, Germany
| | - P. Louarn
- grid.15781.3a0000 0001 0723 035XInstitut de Recherche en Astrophysique et Planétologie, Centre National de la Recherche Scientifique, Centre National d’Etudes Spatiales, Université Paul Sabatier—Toulouse III, Toulouse, France
| | - C. J. Owen
- grid.83440.3b0000000121901201Mullard Space Science Laboratory, University College London, Holmbury St. Mary, UK
| | - T. S. Horbury
- grid.7445.20000 0001 2113 8111Imperial College London, South Kensington Campus, London, UK
| | - K. Asamura
- grid.62167.340000 0001 2220 7916Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Kyoto, Japan
| | - S. Matsuda
- grid.9707.90000 0001 2308 3329Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa, Japan
| | - H. Nilsson
- grid.425140.60000 0001 0706 1867Swedish Institute of Space Physics, Kiruna, Sweden
| | - M. Wieser
- grid.425140.60000 0001 0706 1867Swedish Institute of Space Physics, Kiruna, Sweden
| | - T. Alberti
- grid.4293.c0000 0004 1792 8585Institute of Space Astrophysics and Planetology, Istituto Nazionale di Astrofisica, Rome, Italy
| | - A. Varsani
- grid.4299.60000 0001 2169 3852Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - V. Mangano
- grid.4293.c0000 0004 1792 8585Institute of Space Astrophysics and Planetology, Istituto Nazionale di Astrofisica, Rome, Italy
| | - A. Mura
- grid.4293.c0000 0004 1792 8585Institute of Space Astrophysics and Planetology, Istituto Nazionale di Astrofisica, Rome, Italy
| | - H. Lichtenegger
- grid.4299.60000 0001 2169 3852Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - G. Laky
- grid.4299.60000 0001 2169 3852Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - H. Jeszenszky
- grid.4299.60000 0001 2169 3852Space Research Institute, Austrian Academy of Sciences, Graz, Austria
| | - K. Masunaga
- grid.62167.340000 0001 2220 7916Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Kyoto, Japan
| | - C. Signoles
- grid.15781.3a0000 0001 0723 035XInstitut de Recherche en Astrophysique et Planétologie, Centre National de la Recherche Scientifique, Centre National d’Etudes Spatiales, Université Paul Sabatier—Toulouse III, Toulouse, France
| | - M. Rojo
- grid.15781.3a0000 0001 0723 035XInstitut de Recherche en Astrophysique et Planétologie, Centre National de la Recherche Scientifique, Centre National d’Etudes Spatiales, Université Paul Sabatier—Toulouse III, Toulouse, France
| | - G. Murakami
- grid.62167.340000 0001 2220 7916Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Kyoto, Japan
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3
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Kasper JC, Bale SD, Belcher JW, Berthomier M, Case AW, Chandran BDG, Curtis DW, Gallagher D, Gary SP, Golub L, Halekas JS, Ho GC, Horbury TS, Hu Q, Huang J, Klein KG, Korreck KE, Larson DE, Livi R, Maruca B, Lavraud B, Louarn P, Maksimovic M, Martinovic M, McGinnis D, Pogorelov NV, Richardson JD, Skoug RM, Steinberg JT, Stevens ML, Szabo A, Velli M, Whittlesey PL, Wright KH, Zank GP, MacDowall RJ, McComas DJ, McNutt RL, Pulupa M, Raouafi NE, Schwadron NA. Alfvénic velocity spikes and rotational flows in the near-Sun solar wind. Nature 2019; 576:228-231. [PMID: 31802006 DOI: 10.1038/s41586-019-1813-z] [Citation(s) in RCA: 216] [Impact Index Per Article: 43.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Accepted: 10/17/2019] [Indexed: 11/09/2022]
Abstract
The prediction of a supersonic solar wind1 was first confirmed by spacecraft near Earth2,3 and later by spacecraft at heliocentric distances as small as 62 solar radii4. These missions showed that plasma accelerates as it emerges from the corona, aided by unidentified processes that transport energy outwards from the Sun before depositing it in the wind. Alfvénic fluctuations are a promising candidate for such a process because they are seen in the corona and solar wind and contain considerable energy5-7. Magnetic tension forces the corona to co-rotate with the Sun, but any residual rotation far from the Sun reported until now has been much smaller than the amplitude of waves and deflections from interacting wind streams8. Here we report observations of solar-wind plasma at heliocentric distances of about 35 solar radii9-11, well within the distance at which stream interactions become important. We find that Alfvén waves organize into structured velocity spikes with duration of up to minutes, which are associated with propagating S-like bends in the magnetic-field lines. We detect an increasing rotational component to the flow velocity of the solar wind around the Sun, peaking at 35 to 50 kilometres per second-considerably above the amplitude of the waves. These flows exceed classical velocity predictions of a few kilometres per second, challenging models of circulation in the corona and calling into question our understanding of how stars lose angular momentum and spin down as they age12-14.
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Affiliation(s)
- J C Kasper
- Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI, USA. .,Smithsonian Astrophysical Observatory, Cambridge, MA, USA.
| | - S D Bale
- Physics Department, University of California, Berkeley, CA, USA.,Space Sciences Laboratory, University of California, Berkeley, CA, USA.,The Blackett Laboratory, Imperial College London, London, UK
| | - J W Belcher
- Kavli Center for Astrophysics and Space Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - M Berthomier
- Laboratoire de Physique des Plasmas, CNRS, Sorbonne Université, Ecole Polytechnique, Observatoire de Paris, Université Paris-Saclay, Paris, France
| | - A W Case
- Smithsonian Astrophysical Observatory, Cambridge, MA, USA
| | - B D G Chandran
- Department of Physics and Astronomy, University of New Hampshire, Durham, NH, USA.,Space Science Center, University of New Hampshire, Durham, NH, USA
| | - D W Curtis
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - D Gallagher
- Heliophysics and Planetary Science Branch ST13, Marshall Space Flight Center, Huntsville, AL, USA
| | - S P Gary
- Los Alamos National Laboratory, Los Alamos, NM, USA
| | - L Golub
- Smithsonian Astrophysical Observatory, Cambridge, MA, USA
| | - J S Halekas
- Department of Physics and Astronomy, University of Iowa, IA, USA
| | - G C Ho
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - T S Horbury
- The Blackett Laboratory, Imperial College London, London, UK
| | - Q Hu
- Department of Space Science and Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL, USA
| | - J Huang
- Climate and Space Sciences and Engineering, University of Michigan, Ann Arbor, MI, USA
| | - K G Klein
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.,Department of Planetary Sciences, University of Arizona, Tucson, AZ, USA
| | - K E Korreck
- Smithsonian Astrophysical Observatory, Cambridge, MA, USA
| | - D E Larson
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - R Livi
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - B Maruca
- Department of Physics and Astronomy, University of Delaware, Newark, DE, USA.,Bartol Research Institute, University of Delaware, Newark, DE, USA
| | - B Lavraud
- Institut de Recherche en Astrophysique et Planétologie, CNRS, UPS, CNES, Université de Toulouse, Toulouse, France
| | - P Louarn
- Institut de Recherche en Astrophysique et Planétologie, CNRS, UPS, CNES, Université de Toulouse, Toulouse, France
| | - M Maksimovic
- LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, Meudon, France
| | - M Martinovic
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - D McGinnis
- Department of Physics and Astronomy, University of Iowa, IA, USA
| | - N V Pogorelov
- Department of Space Science and Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL, USA
| | - J D Richardson
- Kavli Center for Astrophysics and Space Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - R M Skoug
- Los Alamos National Laboratory, Los Alamos, NM, USA
| | | | - M L Stevens
- Smithsonian Astrophysical Observatory, Cambridge, MA, USA
| | - A Szabo
- NASA/Goddard Space Flight Center, Greenbelt, MD, USA
| | - M Velli
- Department of Earth, Planetary and Space Sciences, University of California, Los Angeles, CA, USA
| | - P L Whittlesey
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - K H Wright
- Universities Space Research Association, Science and Technology Institute, Huntsville, AL, USA
| | - G P Zank
- Department of Space Science and Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, Huntsville, AL, USA
| | - R J MacDowall
- NASA/Goddard Space Flight Center, Greenbelt, MD, USA
| | - D J McComas
- Department of Astrophysical Sciences, Princeton University, Princeton, NJ, USA
| | - R L McNutt
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - M Pulupa
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - N E Raouafi
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - N A Schwadron
- Department of Physics and Astronomy, University of New Hampshire, Durham, NH, USA.,Space Science Center, University of New Hampshire, Durham, NH, USA
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4
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Owens MJ, Riley P, Horbury TS. Probabilistic Solar Wind and Geomagnetic Forecasting Using an Analogue Ensemble or "Similar Day" Approach. Sol Phys 2017; 292:69. [PMID: 32055078 PMCID: PMC6991991 DOI: 10.1007/s11207-017-1090-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 03/30/2017] [Indexed: 06/07/2023]
Abstract
Effective space-weather prediction and mitigation requires accurate forecasting of near-Earth solar-wind conditions. Numerical magnetohydrodynamic models of the solar wind, driven by remote solar observations, are gaining skill at forecasting the large-scale solar-wind features that give rise to near-Earth variations over days and weeks. There remains a need for accurate short-term (hours to days) solar-wind forecasts, however. In this study we investigate the analogue ensemble (AnEn), or "similar day", approach that was developed for atmospheric weather forecasting. The central premise of the AnEn is that past variations that are analogous or similar to current conditions can be used to provide a good estimate of future variations. By considering an ensemble of past analogues, the AnEn forecast is inherently probabilistic and provides a measure of the forecast uncertainty. We show that forecasts of solar-wind speed can be improved by considering both speed and density when determining past analogues, whereas forecasts of the out-of-ecliptic magnetic field [ B N ] are improved by also considering the in-ecliptic magnetic-field components. In general, the best forecasts are found by considering only the previous 6 - 12 hours of observations. Using these parameters, the AnEn provides a valuable probabilistic forecast for solar-wind speed, density, and in-ecliptic magnetic field over lead times from a few hours to around four days. For B N , which is central to space-weather disturbance, the AnEn only provides a valuable forecast out to around six to seven hours. As the inherent predictability of this parameter is low, this is still likely a marked improvement over other forecast methods. We also investigate the use of the AnEn in forecasting geomagnetic indices Dst and Kp. The AnEn provides a valuable probabilistic forecast of both indices out to around four days. We outline a number of future improvements to AnEn forecasts of near-Earth solar-wind and geomagnetic conditions.
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Affiliation(s)
- M. J. Owens
- Space and Atmospheric Electricity Group, Department of Meteorology, University of Reading, Earley Gate, PO Box 243, Reading, RG6 6BB UK
| | - P. Riley
- Predictive Science Inc., 9990 Mesa Rim Rd, Suite 170, San Diego, CA 92121 USA
| | - T. S. Horbury
- Blackett Laboratory, Imperial College London, London, SW7 2BZ UK
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5
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Bale SD, Goetz K, Harvey PR, Turin P, Bonnell JW, de Wit TD, Ergun RE, MacDowall RJ, Pulupa M, Andre M, Bolton M, Bougeret JL, Bowen TA, Burgess D, Cattell CA, Chandran BDG, Chaston CC, Chen CHK, Choi MK, Connerney JE, Cranmer S, Diaz-Aguado M, Donakowski W, Drake JF, Farrell WM, Fergeau P, Fermin J, Fischer J, Fox N, Glaser D, Goldstein M, Gordon D, Hanson E, Harris SE, Hayes LM, Hinze JJ, Hollweg JV, Horbury TS, Howard RA, Hoxie V, Jannet G, Karlsson M, Kasper JC, Kellogg PJ, Kien M, Klimchuk JA, Krasnoselskikh VV, Krucker S, Lynch JJ, Maksimovic M, Malaspina DM, Marker S, Martin P, Martinez-Oliveros J, McCauley J, McComas DJ, McDonald T, Meyer-Vernet N, Moncuquet M, Monson SJ, Mozer FS, Murphy SD, Odom J, Oliverson R, Olson J, Parker EN, Pankow D, Phan T, Quataert E, Quinn T, Ruplin SW, Salem C, Seitz D, Sheppard DA, Siy A, Stevens K, Summers D, Szabo A, Timofeeva M, Vaivads A, Velli M, Yehle A, Werthimer D, Wygant JR. The FIELDS Instrument Suite for Solar Probe Plus: Measuring the Coronal Plasma and Magnetic Field, Plasma Waves and Turbulence, and Radio Signatures of Solar Transients. Space Sci Rev 2016; 204:49-82. [PMID: 29755144 PMCID: PMC5942226 DOI: 10.1007/s11214-016-0244-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
NASA's Solar Probe Plus (SPP) mission will make the first in situ measurements of the solar corona and the birthplace of the solar wind. The FIELDS instrument suite on SPP will make direct measurements of electric and magnetic fields, the properties of in situ plasma waves, electron density and temperature profiles, and interplanetary radio emissions, amongst other things. Here, we describe the scientific objectives targeted by the SPP/FIELDS instrument, the instrument design itself, and the instrument concept of operations and planned data products.
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Affiliation(s)
- S D Bale
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
- Physics Department, University of California, Berkeley, CA, USA
| | - K Goetz
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA
| | - P R Harvey
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - P Turin
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - J W Bonnell
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - T Dudok de Wit
- LPC2E, CNRS, 3A avenue de la Recherche Scientifique, Orléans, France
| | - R E Ergun
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
| | - R J MacDowall
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - M Pulupa
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - M Andre
- Swedish Institute of Space Physics (IRF), Uppsala, Sweden
| | - M Bolton
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
| | | | - T A Bowen
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
- Physics Department, University of California, Berkeley, CA, USA
| | - D Burgess
- Astronomy Unit, Queen Mary, University of London, London, UK
| | - C A Cattell
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA
| | - B D G Chandran
- Department of Physics, University of New Hampshire, Durham, NH, USA
| | - C C Chaston
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - C H K Chen
- Department of Physics, Imperial College, London, UK
| | - M K Choi
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - J E Connerney
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - S Cranmer
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
| | - M Diaz-Aguado
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - W Donakowski
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - J F Drake
- Department of Physics, University of Maryland, College Park, MD, USA
| | - W M Farrell
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - P Fergeau
- LPC2E, CNRS, 3A avenue de la Recherche Scientifique, Orléans, France
| | - J Fermin
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - J Fischer
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - N Fox
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - D Glaser
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - M Goldstein
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - D Gordon
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - E Hanson
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
- Physics Department, University of California, Berkeley, CA, USA
| | - S E Harris
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - L M Hayes
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - J J Hinze
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA
| | - J V Hollweg
- Department of Physics, University of New Hampshire, Durham, NH, USA
| | - T S Horbury
- Department of Physics, Imperial College, London, UK
| | - R A Howard
- Space Science Division, Naval Research Laboratory, Washington, DC, USA
| | - V Hoxie
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
| | - G Jannet
- LPC2E, CNRS, 3A avenue de la Recherche Scientifique, Orléans, France
| | - M Karlsson
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
| | - J C Kasper
- University of Michigan, Ann Arbor, MI, USA
| | - P J Kellogg
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA
| | - M Kien
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
| | - J A Klimchuk
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | | | - S Krucker
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - J J Lynch
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA
| | | | - D M Malaspina
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
| | - S Marker
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - P Martin
- LPC2E, CNRS, 3A avenue de la Recherche Scientifique, Orléans, France
| | | | - J McCauley
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - D J McComas
- Southwest Research Institute, San Antonio, TX, USA
| | - T McDonald
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | | | - M Moncuquet
- LESIA, Observatoire de Paris, Meudon, France
| | - S J Monson
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA
| | - F S Mozer
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - S D Murphy
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - J Odom
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - R Oliverson
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - J Olson
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - E N Parker
- Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL, USA
| | - D Pankow
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - T Phan
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - E Quataert
- Astronomy Department, University of California, Berkeley, CA, USA
| | - T Quinn
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | | | - C Salem
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - D Seitz
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - D A Sheppard
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - A Siy
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - K Stevens
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
| | - D Summers
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
| | - A Szabo
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - M Timofeeva
- LPC2E, CNRS, 3A avenue de la Recherche Scientifique, Orléans, France
| | - A Vaivads
- Swedish Institute of Space Physics (IRF), Uppsala, Sweden
| | - M Velli
- Earth, Planetary, and Space Sciences, UCLA, Los Angelos, CA, USA
| | - A Yehle
- Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
| | - D Werthimer
- Space Sciences Laboratory, University of California, Berkeley, CA, USA
| | - J R Wygant
- School of Physics and Astronomy, University of Minnesota, Minneapolis, MN, USA
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Brown P, Whiteside BJ, Beek TJ, Fox P, Horbury TS, Oddy TM, Archer MO, Eastwood JP, Sanz-Hernández D, Sample JG, Cupido E, O'Brien H, Carr CM. Space magnetometer based on an anisotropic magnetoresistive hybrid sensor. Rev Sci Instrum 2014; 85:125117. [PMID: 25554336 DOI: 10.1063/1.4904702] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report on the design and development of a low resource, dual sensor vector magnetometer for space science applications on very small spacecraft. It is based on a hybrid device combining an orthogonal triad of commercial anisotropic magnetoresistive (AMR) sensors with a totem pole H-Bridge drive on a ceramic substrate. The drive enables AMR operation in the more sensitive flipped mode and this is achieved without the need for current spike transmission down a sensor harness. The magnetometer has sensitivity of better than 3 nT in a 0-10 Hz band and a total mass of 104 g. Three instruments have been launched as part of the TRIO-CINEMA space weather mission, inter-calibration against the International Geomagnetic Reference Field model makes it possible to extract physical signals such as field-aligned current deflections of 20-60 nT within an approximately 45,000 nT ambient field.
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Affiliation(s)
- P Brown
- Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
| | - B J Whiteside
- Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
| | - T J Beek
- Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
| | - P Fox
- Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
| | - T S Horbury
- Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
| | - T M Oddy
- Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
| | - M O Archer
- Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
| | - J P Eastwood
- Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
| | | | - J G Sample
- Space Sciences Laboratory, University of California, Berkeley, California 94720, USA
| | - E Cupido
- Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
| | - H O'Brien
- Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
| | - C M Carr
- Blackett Laboratory, Imperial College London, London SW7 2BW, United Kingdom
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7
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Owens MJ, Horbury TS, Wicks RT, McGregor SL, Savani NP, Xiong M. Ensemble downscaling in coupled solar wind-magnetosphere modeling for space weather forecasting. Space Weather 2014; 12:395-405. [PMID: 26213518 PMCID: PMC4508929 DOI: 10.1002/2014sw001064] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 05/06/2014] [Indexed: 06/07/2023]
Abstract
UNLABELLED Advanced forecasting of space weather requires simulation of the whole Sun-to-Earth system, which necessitates driving magnetospheric models with the outputs from solar wind models. This presents a fundamental difficulty, as the magnetosphere is sensitive to both large-scale solar wind structures, which can be captured by solar wind models, and small-scale solar wind "noise," which is far below typical solar wind model resolution and results primarily from stochastic processes. Following similar approaches in terrestrial climate modeling, we propose statistical "downscaling" of solar wind model results prior to their use as input to a magnetospheric model. As magnetospheric response can be highly nonlinear, this is preferable to downscaling the results of magnetospheric modeling. To demonstrate the benefit of this approach, we first approximate solar wind model output by smoothing solar wind observations with an 8 h filter, then add small-scale structure back in through the addition of random noise with the observed spectral characteristics. Here we use a very simple parameterization of noise based upon the observed probability distribution functions of solar wind parameters, but more sophisticated methods will be developed in the future. An ensemble of results from the simple downscaling scheme are tested using a model-independent method and shown to add value to the magnetospheric forecast, both improving the best estimate and quantifying the uncertainty. We suggest a number of features desirable in an operational solar wind downscaling scheme. KEY POINTS Solar wind models must be downscaled in order to drive magnetospheric models Ensemble downscaling is more effective than deterministic downscaling The magnetosphere responds nonlinearly to small-scale solar wind fluctuations.
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Affiliation(s)
- M J Owens
- Space Environment Physics Group, Department of Meteorology, University of Reading Reading, UK
| | - T S Horbury
- Space and Atmospheric Physics, Imperial College London London, UK
| | - R T Wicks
- NASA Goddard Space Flight Center Greenbelt, Maryland, USA ; Astronomy Department, University of Maryland College Park, Maryland, USA
| | - S L McGregor
- Department of Physics and Astronomy, Dartmouth College Hanover, New Hampshire, USA
| | - N P Savani
- NASA Goddard Space Flight Center Greenbelt, Maryland, USA ; School of Physics, Astronomy, Computational Sciences, George Mason University Fairfax, Virginia, USA
| | - M Xiong
- State Key Laboratory for SpaceWeather, Center for Space Science and Applied Research, Chinese Academy of Sciences Beijing, China
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Wicks RT, Mallet A, Horbury TS, Chen CHK, Schekochihin AA, Mitchell JJ. Alignment and scaling of large-scale fluctuations in the solar wind. Phys Rev Lett 2013; 110:025003. [PMID: 23383909 DOI: 10.1103/physrevlett.110.025003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2012] [Revised: 09/24/2012] [Indexed: 06/01/2023]
Abstract
We investigate the dependence of solar wind fluctuations measured by the Wind spacecraft on scale and on the degree of alignment between oppositely directed Elsasser fields. This alignment controls the strength of the nonlinear interactions and, therefore, the turbulence. We find that at scales larger than the outer scale of the turbulence the Elsasser fluctuations become on average more antialigned as the outer scale is approached from above. Conditioning structure functions using the alignment angle reveals turbulent scaling of unaligned fluctuations at scales previously believed to lie outside the turbulent cascade in the "1/f range." We argue that the 1/f range contains a mixture of a noninteracting antialigned population of Alfvén waves and magnetic force-free structures plus a subdominant population of unaligned cascading turbulent fluctuations.
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Affiliation(s)
- R T Wicks
- Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.
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9
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Wicks RT, Horbury TS, Chen CHK, Schekochihin AA. Anisotropy of imbalanced Alfvénic turbulence in fast solar wind. Phys Rev Lett 2011; 106:045001. [PMID: 21405329 DOI: 10.1103/physrevlett.106.045001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Indexed: 05/30/2023]
Abstract
We present the first measurement of the scale-dependent power anisotropy of Elsasser variables in imbalanced fast solar wind turbulence. The dominant Elsasser mode is isotropic at lower spacecraft frequencies but becomes increasingly anisotropic at higher frequencies. The subdominant mode is anisotropic throughout. There are two distinct subranges exhibiting different scalings within what is normally considered the inertial range. The low Alfvén ratio and the different scaling of the Elsasser modes suggests an interpretation of the observed discrepancy between the velocity and magnetic field scalings, the total energy is dominated by the latter. These results do not appear to be fully explained by any of the current theories of incompressible imbalanced MHD turbulence.
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Affiliation(s)
- R T Wicks
- Space and Atmospheric Physics Group, Imperial College London, London, United Kingdom.
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10
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Chen CHK, Horbury TS, Schekochihin AA, Wicks RT, Alexandrova O, Mitchell J. Anisotropy of solar wind turbulence between ion and electron scales. Phys Rev Lett 2010; 104:255002. [PMID: 20867388 DOI: 10.1103/physrevlett.104.255002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Indexed: 05/29/2023]
Abstract
The anisotropy of turbulence in the fast solar wind, between the ion and electron gyroscales, is directly observed using a multispacecraft analysis technique. Second order structure functions are calculated at different angles to the local magnetic field, for magnetic fluctuations both perpendicular and parallel to the mean field. In both components, the structure function value at large angles to the field S{⊥} is greater than at small angles S{∥}: in the perpendicular component S{⊥}/S{∥}=5±1 and in the parallel component S{⊥}/S{∥}>3, implying spatially anisotropic fluctuations, k{⊥}>k{∥}. The spectral index of the perpendicular component is -2.6 at large angles and -3 at small angles, in broad agreement with critically balanced whistler and kinetic Alfvén wave predictions. For the parallel component, however, it is shallower than -1.9, which is considerably less steep than predicted for a kinetic Alfvén wave cascade.
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Affiliation(s)
- C H K Chen
- The Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom.
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11
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Owens MJ, Arge CN, Crooker NU, Schwadron NA, Horbury TS. Estimating total heliospheric magnetic flux from single-point in situ measurements. ACTA ACUST UNITED AC 2008. [DOI: 10.1029/2008ja013677] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- M. J. Owens
- Center for Space Physics; Boston University; Boston Massachusetts USA
| | - C. N. Arge
- Space Vehicles Directorate; Air Force Research Laboratory; Kirtland Air Force Base New Mexico USA
| | - N. U. Crooker
- Center for Space Physics; Boston University; Boston Massachusetts USA
| | - N. A. Schwadron
- Center for Space Physics; Boston University; Boston Massachusetts USA
| | - T. S. Horbury
- Space and Atmospheric Physics, Blackett Laboratory; Imperial College London; London UK
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12
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Bale SD, Kellogg PJ, Mozer FS, Horbury TS, Reme H. Measurement of the electric fluctuation spectrum of magnetohydrodynamic turbulence. Phys Rev Lett 2005; 94:215002. [PMID: 16090328 DOI: 10.1103/physrevlett.94.215002] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2005] [Indexed: 05/03/2023]
Abstract
Magnetohydrodynamic (MHD) turbulence in the solar wind is observed to show the spectral behavior of classical Kolmogorov fluid turbulence over an inertial subrange and departures from this at short wavelengths, where energy should be dissipated. Here we present the first measurements of the electric field fluctuation spectrum over the inertial and dissipative wave number ranges in a Beta > or approximately = 1 plasma. The k(-5/3) inertial subrange is observed and agrees strikingly with the magnetic fluctuation spectrum; the wave phase speed in this regime is shown to be consistent with the Alfvén speed. At smaller wavelengths krho(i) > or = 1 the electric spectrum is enhanced and is consistent with the expected dispersion relation of short-wavelength kinetic Alfvén waves. Kinetic Alfvén waves damp on the solar wind ions and electrons and may act to isotropize them. This effect may explain the fluidlike nature of the solar wind.
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Affiliation(s)
- S D Bale
- Department of Physics and Space Sciences Laboratory, University of California, Berkeley, California 94720, USA
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13
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Abstract
Measurements of a spacecraft floating potential, on the four Cluster spacecraft, are used as a proxy for electron plasma density to study, for the first time, the macroscopic density transition scale at 98 crossings of the quasiperpendicular terrestrial bow shock. A timing analysis gives shock speeds and normals; the shock speed is used to convert the temporal measurement to a spatial one. A hyperbolic tangent function is fitted to each density transition, which captures the main shock transition, but not overshoot or undershoot nor foot features. We find that, at a low Mach number M, the density transition is consistent with both ion inertial scales c/omega(pi) and convected gyroradii v(sh,n)/Omega(ci,2), while at M>/=4-5 only the convected gyroradius is the preferred scale for the shock density transition and takes the value L approximately 0.4v(sh,n)/Omega(ci,2).
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Affiliation(s)
- S D Bale
- Space Sciences Laboratory and Department of Physics, University of California, Berkeley, California 94720, USA.
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14
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Horbury TS, Cargill PJ, Lucek EA, Eastwood J, Balogh A, Dunlop MW, Fornacon KH, Georgescu E. Four spacecraft measurements of the quasiperpendicular terrestrial bow shock: Orientation and motion. ACTA ACUST UNITED AC 2002. [DOI: 10.1029/2001ja000273] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
| | | | - E. A. Lucek
- Blackett Laboratory; Imperial College; London UK
| | - J. Eastwood
- Blackett Laboratory; Imperial College; London UK
| | - A. Balogh
- Blackett Laboratory; Imperial College; London UK
| | - M. W. Dunlop
- Blackett Laboratory; Imperial College; London UK
| | - K.-H. Fornacon
- Institut für Geophysik und Meteorologie; Technische Universitat; Braunschweig Germany
| | - E. Georgescu
- Max-Planck-Institut für Extraterrestrische Physik; Garching Germany
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15
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Horbury TS, Balogh A. Evolution of magnetic field fluctuations in high-speed solar wind streams: Ulysses and Helios observations. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2000ja000108] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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17
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Balogh A, Southwood DJ, Forsyth RJ, Horbury TS, Smith EJ, Tsurutani BT. The Heliospheric Magnetic Field Over the South Polar Region of the Sun. Science 1995; 268:1007-10. [PMID: 17774226 DOI: 10.1126/science.268.5213.1007] [Citation(s) in RCA: 221] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Magnetic field measurements from the Ulysses space mission overthe south polar regions of the sun showed that the structure and properties of the three-dimensional heliosphere were determined by the fast solar wind flow and magnetic fields from the large coronal holes in the polar regions of the sun. This conclusion applies at the current, minimum phase of the 11-year solar activity cycle. Unexpectedly, the radial component of the magnetic field was independent of latitude. The high-latitude magnetic field deviated significantly from the expected Parker geometry, probably because of large amplitude transverse fluctuations. Low-frequency fluctuations had a high level of variance. The rate of occurrence of discontinuities also increased significantly at high latitudes.
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