Slavin, J.A. (1), E. Tanskanen (1), C.J. Owen (2), M.W. Dunlop (3), E. Lucek (4), A. Balogh (4), and K.-H Glassmeier (5)

(1) GSFC

2) Mullard Space Science Laboratory, England, UK

3) Rutherford Appleton Laboratory, England, UK

4) Imperial College, England, UK

5) Institut fur Geophysik und Meteorologie, Technische Universitat, Braunschweig, Germany)

Cluster observations of TCRs and magnetic flux removal from the lobes of the near-tail

Abstract

Here we report the frequent observation by Cluster of traveling compression regions (TCRs) and accompanying rarefaction wave fronts in the lobes of the near-tail. Using the 4 spacecraft magnetic field measurements, the propagation speeds for the TCRs are determined. The ratio of the earthward to tailward propagating TCRs and rarefactions at X ~ -16 to -18 Re is approximately 4 to 1. Their mean speed of propagation is comparable to that of BBFs, i.e. ~ 800 km/s. Furthermore, the directions of propagation of the TCRs shows evidence of deflection about the inner magnetosphere as reported for BBFs. These speeds and the temporal durations of the TCRs imply spatial widths of ~ 3 - 4 Re in close agreement with the dimensions of the magnetic flux ropes observed in the near-tail plasma sheet by Geotail and Cluster. Many of the TCRs are coincident with a rarefaction wave front that removes magnetic flux from the tail lobes. Our results suggest that the generation of bursty bulk flows and the removal of magnetic flux from the tail lobes are closely associated with the simultaneous occurrence of reconnection a multiple X-lines in the plasma sheet.