HR: 0800h
AN: SM51C-0393    [Abstracts]
TI: Ionospheric Signatures of Plasma Injections in the Cusp Triggered by Solar Wind Pressure Pulses
AU: Cerisier, J
EM: cerisier@cetp.ipsl.fr
AF: CETP, 4 Av.de Neptune, Saint Maur, 94107 France
AU: Marchaudon, A
EM: am@mssl.ucl.ac.uk
AF: MSSL, Holmbury Street, Mary, Dor RH5 6NT United Kingdom
AU: Bosqued, J
EM: bosqued@cesr.fr
AF: CESR, 9 Av. du colonnel Roche BP 4346, Toulouse, 31028 France
AU: McWilliams, K
EM: kathryn.mcwilliams@usask.ca
AF: University of Saskatchewan, 116 Science Place, Saskatoon, SK S7N 5E2 Canada
AU: Frey, H
EM: hfrey@ssl.berkeley.edu
AF: SSL, Univ. California 7 Gauss way, Berkeley, CA 94720-7450 United States
AU: * Bouhram, M
EM: bouhram@cetp.ipsl.fr
AF: CETP, 4 Av.de Neptune, Saint Maur, 94107 France
AU: Forster, M
AF: MPI, Giessenbachstrasse, Garching, 85741 Germany
AB: During sporadic reconnection events (flux transfer events or FTEs) at the dayside magnetopause, magnetosheath plasma enters the magnetosphere along cusp field lines. It is expected that these enhanced parallel plasma flows occur in conjunction with enhanced ionospheric convection events driven by the magnetic tension at the reconnection site. Associated optical auroral emissions result from enhanced precipitation of the magnetosheath plasma. If such events have long been recognised as due to IMF variations, the triggering role of solar wind pressure pulses is not definitely established. We analyse coordinated observations made on July 14, 2001 simultaneously in the mid-altitude cusp by Cluster and at the ionospheric magnetic footprint by SuperDARN and IMAGE during a period of three successive solar wind dynamic pressure pulses. In association with each of these pulses, Cluster observes plasma injections while auroral images from the IMAGE spacecraft show enhanced precipitation in the cusp. Following these plasma injections, convection flow channels are observed in the ionosphere by the SuperDARN radars. Based on the spatial and temporal relation between these various signatures, a description of the response of the dayside magnetosphere to the pressure pulses is proposed. The main considerations involved in this description are: (1) the solar wind dynamic pressure pulses are the drivers of plasma injections from the magnetosheath. (2) The ionospheric convection bursts start shortly after the auroral intensifications and their duration is much longer (10 min as against 4 to 6 min for the auroral intensifications). (3) The convection bursts do not occur at the same latitude as the precipitation, but on the poleward side of the cusp precipitation. (4) Alfv‚n waves are responsible of the transmission of the magnetic stress from the reconnection site to the ionosphere where they are strongly attenuated by reflection in the upper ionosphere. This set of observations demonstrates that the convection bursts are a "fossil" signature of the compression-injection process as it is also the case for reconnection at the dayside magnetopause driven by the IMF alone.
DE: 2411 Electric fields (2712)
DE: 2437 Ionospheric dynamics
DE: 2724 Magnetopause, cusp, and boundary layers
DE: 2736 Magnetosphere/ionosphere interactions
SC: SPA-Magnetospheric Physics [SM]
MN: 2004 AGU Fall Meeting