HR: 1340h
AN: SM43A-1154    [Abstracts]
TI: Effects of Ejecta-Ejecta Interactions on the Magnetosphere: The Double Great Storm on March 31, 2001
AU: * Farrugia, C J
EM: charlie.farrugia@unh.edu
AF: Space Science Center and Department of Physics, University of New Hampshire, Durham, NH 03820
AU: Jordanova, V K
EM: vania.jordanova@unh.edu
AF: Space Science Center and Department of Physics, University of New Hampshire, Durham, NH 03820
AU: Berdichevsky, D B
EM: xrdbb@lepvax.gsfc.nasa.gov
AF: NASA/Goddard Space Flight Center, Greenbelt Rd., Greenbelt, MD 20771
AU: Thomsen, M F
EM: michelle.thomsen@lanl.gov
AF: Los Alamos National Lab, Los Alamos, Los Alamos, NM 87545
AU: Lu, G
EM: Gang.Lu@hao.gov
AF: High Altitude Laboratory, Boulder, Boulder, CO 80307
AB: When ejecta interact with each other en route to Earth, their parameters are changed in significant ways, and with it their geoeffectiveness. Among the effects of such interactions are: heating of the plasma, acceleration of the leading ejecta and deceleration of the trailing ejecta, compressed field and plasma in the leading ejecta, disappearance of shocks originally driven by the trailing ejecta, and the strengthening of shocks driven by the accelerated ejecta. Here we model the ring current enhancement and radiation belt behavior and try to isolate the effects these changes had on the magnetosphere when 2 ejecta in the process of coalescing reached Earth on March 31, 2001. The magnetosphere senses the presence of the two ejecta and reacts with a re-activation of the ring current soon after it started to recover from the first ejection, giving rise to a double-dip great storm (Dst < -250 nT). The compression of the plasma in the leading ejecta by itself gives a contribution of > 100 nT to the Dst corrected for magnetopause currents. This is about three times that due (i) to the compression behind the shock and (ii) the compression in the trailing ejecta. The high, but monotonically decreasing, plasma sheet density is probably also a result of the compression of the plasma in the leading ejecta. The non-linear behavior of the magnetosphere is illustrated with the behavior of the cross-polar cap potential, as calculated using the AMIE technique. Acknowledgements. This work is supported by the Wind Grant NAG5-11803 and by NASA Living with a Star Grants NAG5-10883, NAG5-13512, NASW/02035, and NSF Space Weather grants ATM-0208414 and NATM-0309585.
DE: 2111 Ejecta, driver gases, and magnetic clouds
DE: 2435 Ionospheric disturbances
DE: 2778 Ring current
DE: 2784 Solar wind/magnetosphere interactions
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting