AVERAGE PATTERNS OF PRECIPITATION AND PLASMA-FLOW IN THE PLASMA SHEET FLUX TUBES DURING STEADY MAGNETOSPHERIC CONVECTION

Average patterns of plasma drifts and auroral precipitation in the nightside auroral zone were constructed during a steady magnetospheric convection (SMC) event on 19 February 1978. By comparing these patterns with the measurements in the midtail plasma sheet made by ISEE-1, and using the corresponding magnetic field model, we infer the following features: (I) concentration of the earthward convection in the midnight portion of the plasma sheet (convection jet); (2) depleted plasma energy content of the flux tubes in the convection jet region (assuming pVy = K); and (3) Region 1 field-aligned currents generated in the midtail plasma sheet. We argue that these three elements are mutually consistent features appearing in the process of ionosphere-magnetosphere interaction during SMC periods. These configurational characteristics resemble the corresponding features of substorm expansions (enhanced convection and "dipolarized" magnetic field within the substorm current wedge) and appear to play the same role in regulating the plasma flow in the flux tubes connected to the plasma sheet. © 1990.