HR: 16:00h
AN: SM14A-01    [Abstracts]
TI: Comparative Examination of Magnetic Flux Ropes and Traveling Compression Regions in the Cluster and Geotail Observations
AU: * Slavin, J A
EM: james.a.slavin@nasa.gov
AF: NASA GSFC, Code 696, Greenbelt, MD 20771 United States
AU: Tanskanen, E I
EM: etanskanen@lepvax.gsfc.nasa.gov
AF: NASA GSFC, Code 696, Greenbelt, MD 20771 United States
AB: Magnetic flux rope (FR) and traveling compression region (TCR) populations in the near-tail have now been well sampled by the Cluster and Geotail missions. Together, these missions provide detailed measurements from X ~ -10 to -30 Re under both quiet and active times. Using the measurements returned by both of these missions we present statistical analyses showing clear radial and east - west gradients in a number of their key properties. For example, the Bz variations associated with these structures change near X ~ -25 Re from the south-then-north (SN) variation that dominates in the near-tail to the north-then-south (NS) that is usually seen in the distant tail. There is also a strong decrease in the rate of FR/TCR occurrence earthward of X ~ -20 Re probably due to both a decreasing likelihood of reconnection so close to the Earth and the dissipation of flux ropes through "re-reconnection" as they are pushed up against the dipole magnetic fields of the inner magnetosphere. We also found that the mean speeds of the flux ropes and TCRs are very similar at 600- 800 km/s as are their mean diameters of ~ 3 to 4 Re. Overall, the existing observations of FRs and TCRs suggest that dynamics of the near-tail is dominated by simultaneous reconnection at multiple X-lines that filaments the cross-tail current sheet and leads to the formation of a dominant near-Earth neutral line.
DE: 2740 Magnetospheric configuration and dynamics
DE: 2744 Magnetotail
DE: 2788 Storms and substorms
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting