TERRAPUB Earth, Planets and Space

Earth Planets Space, Vol. 53 (No. 6), pp. 619-625, 2001

Evidence for an extended reconnection line at the dayside magnetopause

T. D. Phan1, M. P. Freeman2, L. M. Kistler3, B. Klecker4, G. Haerendel4, G. Paschmann4, B. U. Ö. Sonnerup5, W. Baumjohann4, M. B. Bavassano-Cattaneo6, C. W. Carlson1, A. M. DiLellis6, K.-H. Fornacon7, L. A. Frank8, M. Fujimoto9, E. Georgescu4,10, S. Kokubun11, E. Moebius3, T. Mukai12, W. R. Paterson8, and H. Reme13

1Space Sciences Laboratory, University of California, Berkeley, CA 94720, U.S.A.
2British Antarctic Survey, Cambridge, CB3 OET, United Kingdom
3Space Science Center, University of New Hampshire, NH 03824, U.S.A.
4Max-Planck-Institut für extraterrestrische Physik, 85740 Garching, Germany
5Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, U.S.A.
6IFSI-CNR, 00133 Roma, Italy
7Technische Universität Braunschweig, 38106 Braunschweig, Germany
8Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52242, U.S.A.
9Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Meguro 152-8551, Japan
10Institute of Space Sciences, Bucharest, Romania
11Solar-Terrestrial Environment Laboratory, Nagoya University, Aichi 442-8507, Japan
12The Institute of Space and Astronautical Science, Sagamihara, Kanagawa 229-8510, Japan
13Centre d'Etude Spatiale des Rayonnements, Université Paul Sabatier, Toulouse, France

(Received May 25, 2000; Revised November 7, 2000; Accepted November 27, 2000)

Abstract: We report in-situ detection by two spacecraft of oppositely directed jets of plasma emanating from a magnetic reconnection site at the Earth's dayside magnetopause, confirming a key element inherent in all reconnection scenarios. The dual-spacecraft (Equator-S and Geotail) observations at the flank magnetopause, together with SuperDARN Halley radar observations of the subsolar cusp region, reveal the presence of a rather stable and extended reconnection line which lies along the equatorial magnetopause. These observations were made under persistent southward interplanetary magnetic field (IMF) conditions, implying that under these conditions the reconnection sites are determined by the large-scale interactions between the solar wind magnetic field and the dayside magnetosphere, rather than by local conditions at the magnetopause. Control by local conditions would result in patchy reconnection, distributed in a less well-organized fashion over the magnetopause surface.

Corresponding author E-mail: phan@ssl.berkeley.edu

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