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Cho IH, Moon YJ, Nakariakov VM, Bong SC, Lee JY, Song D, Lee H, Cho KS. Two-Dimensional Solar Wind Speeds from 6 to 26 Solar Radii in Solar Cycle 24 by Using Fourier Filtering. PHYSICAL REVIEW LETTERS 2018; 121:075101. [PMID: 30169071 DOI: 10.1103/physrevlett.121.075101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 05/28/2018] [Indexed: 06/08/2023]
Abstract
Measurement of the solar wind speed near the Sun is important for understanding the acceleration mechanism of the solar wind. In this Letter, we determine 2D solar wind speeds from 6 to 26 solar radii by applying Fourier motion filters to SOHO/LASCO C3 movies observed from 1999 to 2010. Our method successfully reproduces the original flow speeds in the artificially generated data as well as streamer blobs. We measure 2D solar wind speeds from one-day to one-year timescales and their variation in solar cycle 24. We find that the solar wind speeds at timescales longer than a month in the solar maximum period are relatively uniform in the azimuthal direction, while they are clearly bimodal in the minimum period, as expected from the Ulysses observations and interplanetary radio scintillation reconstruction. The bimodal structure appears at around 2006, becomes most distinctive in 2009, and abruptly disappears in 2010. The radial evolution of the solar wind speeds resembles the Parker's solar wind solution.
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Affiliation(s)
- Il-Hyun Cho
- Kyung Hee University, Yongin-si, Gyeonggi-do, 17104, Korea
| | - Yong-Jae Moon
- Kyung Hee University, Yongin-si, Gyeonggi-do, 17104, Korea
| | - Valery M Nakariakov
- Kyung Hee University, Yongin-si, Gyeonggi-do, 17104, Korea
- University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Su-Chan Bong
- Korea Astronomy and Space Science Institute, Yuseong-gu, Daejeon 34055, Korea
- University of Science and Technology, Yuseong-gu, Daejeon 34113, Korea
| | - Jin-Yi Lee
- Kyung Hee University, Yongin-si, Gyeonggi-do, 17104, Korea
| | - Donguk Song
- National Institutes of Natural Sciences, Mitaka, Tokyo 181-8588, Japan
| | - Harim Lee
- Kyung Hee University, Yongin-si, Gyeonggi-do, 17104, Korea
| | - Kyung-Suk Cho
- Korea Astronomy and Space Science Institute, Yuseong-gu, Daejeon 34055, Korea
- University of Science and Technology, Yuseong-gu, Daejeon 34113, Korea
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Sorriso-Valvo L, Marino R, Carbone V, Noullez A, Lepreti F, Veltri P, Bruno R, Bavassano B, Pietropaolo E. Observation of inertial energy cascade in interplanetary space plasma. PHYSICAL REVIEW LETTERS 2007; 99:115001. [PMID: 17930445 DOI: 10.1103/physrevlett.99.115001] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Indexed: 05/20/2023]
Abstract
Direct evidence for the presence of an inertial energy cascade, the most characteristic signature of hydromagnetic turbulence (MHD), is observed in the solar wind by the Ulysses spacecraft. After a brief rederivation of the equivalent of Yaglom's law for MHD turbulence, a linear relation is indeed observed for the scaling of mixed third-order structure functions involving Elsässer variables. This experimental result firmly establishes the turbulent character of low-frequency velocity and magnetic field fluctuations in the solar wind plasma.
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Affiliation(s)
- L Sorriso-Valvo
- Licryl Regional Laboratory - INFM/CNR, Ponte P. Bucci, Cubo 33C, 87036 Rende (CS), Italy
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Smith EJ, Marsden RG, Balogh A, Gloeckler G, Geiss J, McComas DJ, McKibben RB, MacDowall RJ, Lanzerotti LJ, Krupp N, Krueger H, Landgraf M. The Sun and Heliosphere at Solar Maximum. Science 2003; 302:1165-9. [PMID: 14615526 DOI: 10.1126/science.1086295] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Recent Ulysses observations from the Sun's equator to the poles reveal fundamental properties of the three-dimensional heliosphere at the maximum in solar activity. The heliospheric magnetic field originates from a magnetic dipole oriented nearly perpendicular to, instead of nearly parallel to, the Sun's rotation axis. Magnetic fields, solar wind, and energetic charged particles from low-latitude sources reach all latitudes, including the polar caps. The very fast high-latitude wind and polar coronal holes disappear and reappear together. Solar wind speed continues to be inversely correlated with coronal temperature. The cosmic ray flux is reduced symmetrically at all latitudes.
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Affiliation(s)
- E J Smith
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
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Walden AT, Cristan AC. The phase–corrected undecimated discrete wavelet packet transform and its application to interpreting the timing of events. Proc Math Phys Eng Sci 1998. [DOI: 10.1098/rspa.1998.0257] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- A. T. Walden
- Department of Mathematics, Imperial College of Science, Technology and Medicine, 180 Queen's Gate, London SW7 2BZ, UK
| | - A. Contreras Cristan
- Department of Mathematics, Imperial College of Science, Technology and Medicine, 180 Queen's Gate, London SW7 2BZ, UK
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Reiner MJ, Fainberg J, Stone RG. Large-Scale Interplanetary Magnetic Field Configuration Revealed by Solar Radio Bursts. Science 1995. [DOI: 10.1126/science.270.5235.461] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
| | - J. Fainberg
- J. Fainberg and R. G. Stone, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
| | - R. G. Stone
- J. Fainberg and R. G. Stone, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
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