Spatial scale of high-speed flows in the plasma sheet observed by Cluster
Balogh, A.; Zhang, T. L.; Klecker, B.; Kistler, L. M.; Nakamura, R.; Baumjohann, W.; Asano, Y.; Volwerk, M.; Rème, H.; Mouikis, C.; Runov, A.; Vörös, Z.
Abstract
Spatial gradients of high-speed flows in the midtail plasma sheet are determined using multipoint observations from the Cluster spacecraft along the ``dawn-dusk'' direction (perpendicular to the main flow and in the plane of the tail current sheet) and along the north-south direction. If we take the average or median of the spatial gradients and assume that the flow channel has a linear gradient, these values suggest that the full width of the flow channel is 2-3 RE in the ``dawn-dusk'' direction and 1.5-2 RE in the north-south direction. The velocity gradient at the duskward edge of a flow tends to be sharper than that at the dawnward edge, possibly reflecting an asymmetry in the magnetosphere-ionosphere coupling process associated with the flow.