HR: 10:20h
AN: SM52A-01    [Abstracts]
TI: Reconstruction of flux transfer events from Cluster data
AU: Sonnerup, B U
EM: sonnerup@dartmouth.edu
AF: Thayer School of Engineering, Dartmouth College, 8000 Cummings Hall, Hanover, NH 03755 United States
AU: * Hasegawa, H
EM: hiroshi.hasegawa@dartmouth.edu
AF: Thayer School of Engineering, Dartmouth College, 8000 Cummings Hall, Hanover, NH 03755 United States
AU: Klecker, B
EM: berndt.klecker@mpe.mpg.de
AF: Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse, Garching, 85741 Germany
AU: Paschmann, G
EM: goetz.paschmann@mpe.mpg.de
AF: Max-Planck-Institut fuer extraterrestrische Physik, Giessenbachstrasse, Garching, 85741 Germany
AU: Dunlop, M W
EM: M.W.Dunlop@rl.ac.uk
AF: Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 0QX United Kingdom
AU: Reme, H
EM: Henri.Reme@cesr.fr
AF: Centre d'Etude Spatiale des Rayonnements, BP-4346, Toulouse, 31029 France
AB: The structure of flux transfer events (FTEs), encountered by the Cluster satellites near the northern cusp, is visualized using the Grad-Shafranov reconstruction technique. The method produces a map of the FTE cross section, using combined magnetic field and plasma data from all four spacecraft, under the assumptions that the structures are two-dimensional and time-independent. In a test case, the reconstructed FTE consists of a flux rope with diameter \sim1 $R_{E}$, embedded in the magnetopause. The flux rope is more or less rounded and no signatures of currently active reconnection are found, suggesting that it was created by reconnection at low latitudes and that it had reached an approximate equilibrium by the time Cluster encountered it. The orientation of the flux rope axis can be fairly well determined through a process of optimizing the map, the result being consistent with those from various single-spacecraft methods. Thanks to this, the unambiguous presence of the strong core field is confirmed, providing evidence for component merging. The orientation of the reconnection line at which the flux rope was produced can also be deduced. The amount of the magnetic flux in the flux rope can be calculated from the map and, by dividing it by the time separation between consecutive FTEs, we can estimate a lower limit of the reconnection electric field during the formation of the flux rope. The speed of the flux rope along the magnetopause can be determined and is found to be supersonic relative to the magnetospheric plasma. Maps of other FTEs are also shown and the nature of magnetopause reconnection leading to those FTEs is discussed.
DE: 7819 Experimental and mathematical techniques
DE: 7835 Magnetic reconnection
DE: 2724 Magnetopause, cusp, and boundary layers
DE: 2753 Numerical modeling
DE: 2784 Solar wind/magnetosphere interactions
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting