HR: 14:25h
AN: SM13D-03    [Abstracts]
TI: Spatial Structure of Plasmaspheric Plumes Observed by THEMIS
AU: * McFadden, J P
EM: mcfadden@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, Berkeley, CA 94720, United States
AU: Carlson, C
EM: cwc@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, Berkeley, CA 94720, United States
AU: Angelopoulos, V
EM: vassilis@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, Berkeley, CA 94720, United States
AU: Bonnell, J
EM: jbonnell@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, Berkeley, CA 94720, United States
AU: Larson, D
EM: davin@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, Berkeley, CA 94720, United States
AU: Mozer, F
EM: fmozer@ssl.berkeley.edu
AF: Space Sciences Laboratory, University of California, Berkeley, CA 94720, United States
AU: Ergun, R
EM: ree@fast.colorado.edu
AF: LASP, University of Colorado, Bolder, CO 80303, United States
AU: Glassmeier, K
EM: k-h.glassmeier@tu-bs.de
AF: TUBS, Mendelssohnstr 3, Braunschweig, 38106, Germany
AU: Auster, U
EM: uli.auster@tu-bs.de
AF: TUBS, Mendelssohnstr 3, Braunschweig, 38106, Germany
AU: Roux, A
EM: Alain.Roux@cetp.ipsl.fr
AF: CETP, 10-12 avenue de l'Europe, Velizy, 78140, France
AU: LeContel, O
EM: Olivier.LeContel@cetp.ipsl.fr
AF: CETP, 10-12 avenue de l'Europe, Velizy, 78140, France
AB: During the first 6 months of the THEMIS mission, the five spacecraft were configured in a string-of-pearls that sampled the dayside magnetosphere revealing the dominance of cold plasma in this region. Although cold ions can only be detected when MP motion increases their energy in the spacecraft frame allowing penetration of the spacecraft potential, comparisons of electron density with ion density provide identification of the hidden cold ions. Spacecraft potential is also used to infer hidden cold plasma, supporting the plasma measurements. As expected, the largest cold plasma densities are observed in the post-noon sector where plasmaspheric plumes are convected to the magnetopause. These multi-spacecraft measurements offer a unique picture of the spatial and temporal structure of these plumes. Order of magnitude density variations over 100 km scales are observed indicating these plumes can be highly structured. Plume densities >10/cc near the magnetopause were observed on a dozen orbits, with one observation revealing 60/cc. Cold plasma is generally found to dominate the number density in the post-noon sector by a factor of 10-100 over the hot component. These measurements indicate that cold plasma must play a major role in magnetospheric dynamics, affecting wave dispersion relations, field line resonances, and reconnection. This paper will focus on structure revealed by the multi- satellite measurements.
DE: 2724 Magnetopause and boundary layers
DE: 2731 Magnetosphere: outer
DE: 2740 Magnetospheric configuration and dynamics
DE: 2760 Plasma convection (2463)
DE: 2768 Plasmasphere
SC: SPA-Magnetospheric Physics [SM]
MN: 2007 Fall Meeting