Interball-tail observations of vertical plasma motions in the magnetotail

A. A. Petrukovich (1) , Y. I. Yermolaev (1)

1 IKI - Space Research Institute of the Russian Academy of Sciences

The Interball spacecraft configuration favors, in contrast to previous experiments, investigation of vertical ion flows (GSM V_z ). We use measurements of the CORALL instrument for the statistical study of V_z and V_y plasma flows in the mid-tail plasma sheet. In agreement with the previous observations, the mean V_y was positive on the dusk side and negative on the dawn side. When IMF was southward, the mean V_z 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 V_z variance maximized on the dawn flank and was always 15?20% smaller than the V_y one. The V_y 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 V_y in the pre-midnight plasma sheet.

Domaines: Océan, Atmosphère; Sciences de la Terre

A. A. Petrukovich, Y. I. Yermolaev. Interball-tail observations of vertical plasma motions in the magnetotail. Annales Geophysicae, 2002, 20 (3), pp.321-327. ⟨hal-00316951⟩