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Ann. Geophys., 20, 321-327, 2002
www.ann-geophys.net/20/321/2002/
© European Geosciences Union 2002
Interball-tail observations of vertical plasma motions in the magnetotail
A. A. Petrukovich1 and Y. I. Yermolaev1
1Space Research Institute, 84/32 Profsoyuznaya St., Moscow, 117810, Russia
Correspondence to: A. A. Petrukovich
(apetruko@iki.rssi.ru)
Abstract. The Interball spacecraft
configuration favors, in contrast to previous experiments, investigation of
vertical ion flows (GSM Vz ). We use measurements of the CORALL
instrument for the statistical study of Vz and Vy plasma
flows in the mid-tail plasma sheet. In agreement with the previous
observations, the mean Vy was positive on the dusk side and negative
on the dawn side. When IMF was southward, the mean Vz consisted of
the convection flow towards the equatorial plane ~ 7 km/s and the northward
flow ~ 8 km/s. When IMF was northward, both components nearly vanished. The
velocity variance was much larger than the mean values. The Vz
variance maximized on the dawn flank and was always 15–20% smaller than the Vy
one. The Vy variance maximized in the pre-midnight sector closer to
the neutral sheet. We conclude that velocity fluctuations are composed with the
inherent high-beta plasma turbulence contributing to all components, and the
BBF-related activity contributing mainly to Vy in the pre-midnight
plasma sheet.
Key words. Magnetospheric physics (magnetotail;
plasma sheet; plasma convection)
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