HR: 0800h
AN: SM51A-0280    [Abstracts]
TI: Temporal Development of Auroral Acceleration Potentials: High-Altitude Evolutionary Sequences, Drivers and Consequences
AU: * Hull, A J
EM: ahull@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720, United States
AU: Wilber, M
EM: wilber@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720, United States
AU: Chaston, C
EM: ccc@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720, United States
AU: Bonnell, J
EM: jwb@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720, United States
AU: Mozer, F
EM: fmozer@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720, United States
AU: McFadden, J
EM: mcfadden@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720, United States
AU: Goldstein, M
EM: melvyn.l.goldstein@nasa.gov
AF: NASA Goddard Space Flight Center, Code 692, Greenbelt, MD 20771, United States
AU: Fillingim, M
EM: matt@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720, United States
AB: The region above the auroral acceleration region is an integral part of the auroral zone electrodynamic system. At these altitudes (≥ 3 Re) we find the source plasma and fields that determine acceleration processes occurring at lower altitudes, which play a key role in the transport of mass and energy into the ionosphere. Dynamic changes in these high-altitude regions can affect and/or control lower-altitude acceleration processes according to how field-aligned currents and specific plasma sources form and decay and how they are spatially distributed, and through magnetic configuration changes deeper in the magnetotail. Though much progress has been made, the time development and consequential effects of the high-altitude plasma and fields are still not fully understood. We present Cluster multi-point observations at key instances within and above the acceleration region (> 3 R_E) of evolving auroral arc current systems. Results are presented from events occurring under different conditions, such as magnetospheric activity, associations with density depletions or gradients, and Alfvenic turbulence. A preliminary survey, primarily at or near the plasma sheet boundary, indicates quasi- static up-down current pair systems are at times associated with density depletions and other instances occur in association with density gradients. The data suggest that such quasi-static current systems may be evolving from structured Alfvenic current systems. We will discuss the temporal development of auroral acceleration potentials, plasma and currents, including quasi-static system formation from turbulent systems of structured Alfvenic field-aligned currents, density depletion and constituent reorganization of the source and ionospheric plasma that transpire in such systems. Of particular emphasis is how temporal changes in magnetospheric source plasma and fields affect the development of auroral acceleration potentials at lower altitudes.
DE: 2431 Ionosphere/magnetosphere interactions (2736)
DE: 2451 Particle acceleration
DE: 2704 Auroral phenomena (2407)
DE: 2721 Field-aligned currents and current systems (2409)
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting