Ion Bernstein waves in the magnetic reconnection region
Y. Narita1,2,R. Nakamura1,W. Baumjohann1,K.-H. Glassmeier2,3,U. Motschmann4,5,and H. Comişel4,6Y. Narita et al. Y. Narita1,2,R. Nakamura1,W. Baumjohann1,K.-H. Glassmeier2,3,U. Motschmann4,5,and H. Comişel4,6
1Space Research Institute, Austrian Academy of Sciences,
Schmiedlstr. 6, 8042 Graz, Austria
2Institut für Geophysik und
extraterrestrische Physik, Technische Universität Braunschweig,
Mendelssohnstr. 3, 38106 Braunschweig, Germany
3Max-Planck-Institut für Sonnensystemforschung,
Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
4Institut für
Theoretische Physik, Technische Universität Braunschweig, Mendelssohnstr.
3, 38106 Braunschweig, Germany
5Deutsches Zentrum für Luft- und
Raumfahrt, Institut für Planetenforschung, Rutherfordstr. 2, 12489 Berlin,
Germany
6Institute for Space Sciences, Atomiştilor 409,
P.O. Box MG-23, Bucharest-Măgurele, 077125, Romania
1Space Research Institute, Austrian Academy of Sciences,
Schmiedlstr. 6, 8042 Graz, Austria
2Institut für Geophysik und
extraterrestrische Physik, Technische Universität Braunschweig,
Mendelssohnstr. 3, 38106 Braunschweig, Germany
3Max-Planck-Institut für Sonnensystemforschung,
Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany
4Institut für
Theoretische Physik, Technische Universität Braunschweig, Mendelssohnstr.
3, 38106 Braunschweig, Germany
5Deutsches Zentrum für Luft- und
Raumfahrt, Institut für Planetenforschung, Rutherfordstr. 2, 12489 Berlin,
Germany
6Institute for Space Sciences, Atomiştilor 409,
P.O. Box MG-23, Bucharest-Măgurele, 077125, Romania
Correspondence: Y. Narita (yasuhito.narita@oeaw.ac.at)
Received: 02 Dec 2015 – Accepted: 12 Jan 2016 – Published: 21 Jan 2016
Abstract. Four-dimensional energy spectra and a diagram for dispersion relations are determined for the first time in a magnetic reconnection region in the magnetotail using data from four-spacecraft measurements by the Cluster mission on a spatial scale of 200 km, about 0.1 ion inertial lengths. The energy spectra are anisotropic with an extension in the perpendicular direction and axially asymmetric with respect to the mean magnetic field. The dispersion diagram in the plasma rest frame is in reasonably good agreement with the ion Bernstein waves at the second and higher harmonics of the proton gyrofrequency. Perpendicular-propagating ion Bernstein waves likely exist in an outflow region of magnetic reconnection, which may contribute to bifurcation of the current sheet in the outflow region.
Four-spacecraft Cluster observations of turbulent fluctuations in the magnetic reconnection region in the geomagnetic tail show for the first time an indication of ion Bernstein waves, electromagnetic waves that propagate nearly perpendicular to the mean magnetic field and are in resonance with ions. Bernstein waves may influence current sheet dynamics in the reconnection outflow such as a bifurcation of the current sheet.
Four-spacecraft Cluster observations of turbulent fluctuations in the magnetic reconnection...
