HR: 16:30h
AN: SM32D-03    [PDF]
TI: Time and Length Scales of Magnetic Field Variations in the Quasi-Perpendicular Terrestrial Bowshock
AU: * Horbury, T
EM: t.horbury@imperial.ac.uk
AF: Imperial College London, The Blackett Laboratory Prince Consort Road, London, SW7 2BW United Kingdom
AU: Lucek, E
AF: Imperial College London, The Blackett Laboratory Prince Consort Road, London, SW7 2BW United Kingdom
AU: Balogh, A
AF: Imperial College London, The Blackett Laboratory Prince Consort Road, London, SW7 2BW United Kingdom
AU: Dandouras, I
AF: CESR, 9, avenue du Colonel Roche 31028, Toulouse, Cedex 4 France
AU: Reme, H
AF: CESR, 9, avenue du Colonel Roche 31028, Toulouse, Cedex 4 France
AB: The terrestrial bowshock is an example of a moderate Mach number collisionless shock which can be studied in detail. Despite decades of study of the quasi-perpendicular shock, several questions remain, such as the scales of various parts of the shock transition and in particular the time and length scales of its variability. Recent measurements using the four Cluster spacecraft make it possible to measure the orientation and motion of the quasi-perpendicular bowshock surface and also, by comparing profiles measured by different spacecraft, its variability. We present estimates of the variation with Mach number of the ramp, overshoot and undershoot scales and compare these with earlier work. We also discuss the variability of shock structures, such as the peak magnetic field and the ramp itself, and demonstrate that the shock ramp varies on scales of a few seconds, but appears to be stable over scales of hundreds of km.
DE: 2154 Planetary bow shocks
DE: 7851 Shock waves
DE: 7871 Waves and instabilities
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting