Determining <b><i>L</i></b>‐<b><i>M</i></b>‐<b><i>N</i></b> Current Sheet Coordinates at the Magnetopause From Magnetospheric Multiscale Data
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- R. E. Denton
- Department of Physics and Astronomy Dartmouth College Hanover NH USA
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- B. U. Ö. Sonnerup
- Thayer School of Engineering Dartmouth College Hanover NH USA
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- C. T. Russell
- Institute of Geophysics and Planetary Physics University of California Los Angeles CA USA
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- H. Hasegawa
- Institute of Space and Astronautical Science JAXA Sagamihara Japan
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- T.‐D. Phan
- Space Science Laboratory University of California Berkeley CA USA
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- R. J. Strangeway
- Institute of Geophysics and Planetary Physics University of California Los Angeles CA USA
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- B. L. Giles
- NASA Goddard Space Flight Center Greenbelt MD USA
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- R. E Ergun
- Laboratory for Atmospheric and Space Physics University of Colorado Boulder Boulder CO USA
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- P.‐A. Lindqvist
- Space and Plasma Physics Royal Institute of Technology Stockholm Sweden
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- R. B. Torbert
- Institute for the Study of Earth, Oceans, and Space University of New Hampshire Durham NH USA
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- J. L Burch
- Space Science and Engineering Division Southwest Research Institute San Antonio TX USA
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- S. K. Vines
- Space Science and Engineering Division Southwest Research Institute San Antonio TX USA
Description
<jats:title>Abstract</jats:title><jats:p>We discuss methods to determine <jats:italic>L</jats:italic>‐<jats:italic>M</jats:italic>‐<jats:italic>N</jats:italic> coordinate systems for current sheet crossings observed by the Magnetospheric Multiscale (MMS) spacecraft mission during ongoing reconnection, where <jats:bold>e</jats:bold><jats:sub><jats:italic>L</jats:italic></jats:sub> is the direction of the reconnecting component of the magnetic field, <jats:bold>B</jats:bold>, and <jats:bold>e</jats:bold><jats:sub><jats:italic>N</jats:italic></jats:sub> is normal to the magnetopause. We present and test a new hybrid method, with <jats:bold>e</jats:bold><jats:sub><jats:italic>L</jats:italic></jats:sub> estimated as the maximum variance direction of <jats:bold>B</jats:bold> (MVAB) and <jats:bold>e</jats:bold><jats:sub><jats:italic>N</jats:italic></jats:sub> as the direction of maximum directional derivative of <jats:bold>B</jats:bold>, and then adjust these directions to be perpendicular. In the best case, only small adjustment is needed. Results from this method, applied to an MMS crossing of the dayside magnetopause at 1305:45 UT on 16 October 2015, are discussed and compared with those from other methods for which <jats:bold>e</jats:bold><jats:sub><jats:italic>N</jats:italic></jats:sub> is obtained by other means. Each of the other evaluations can be combined with <jats:bold>e</jats:bold><jats:sub><jats:italic>L</jats:italic></jats:sub> from MVAB in a generalized hybrid approach to provide an <jats:italic>L</jats:italic>‐<jats:italic>M</jats:italic>‐<jats:italic>N</jats:italic> system. The quality of the results is judged by eigenvalue ratios, constancy of directions using different data segments and methods, and expected sign and magnitude of the normal component of <jats:bold>B</jats:bold>. For this event, the hybrid method appears to produce <jats:bold>e</jats:bold><jats:sub><jats:italic>N</jats:italic></jats:sub> accurate to within less than 10°. We discuss variance analysis using the electric current density, <jats:bold>J</jats:bold>, or the <jats:bold>J</jats:bold> × <jats:bold>B</jats:bold> force, which yield promising results, and minimum Faraday residue analysis and MVAB alone, which can be useful for other events. We also briefly discuss results from our hybrid method and MVAB alone for a few other MMS reconnection events.</jats:p>
Journal
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- Journal of Geophysical Research: Space Physics
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Journal of Geophysical Research: Space Physics 123 (3), 2274-2295, 2018-03
American Geophysical Union (AGU)
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Details 詳細情報について
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- CRID
- 1360567179761726976
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- ISSN
- 21699402
- 21699380
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- Data Source
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- Crossref
- KAKEN