Global x-ray observations of magnetospheric convection-driven auroral disturbances

Global observations of the auroral x-ray emissions during three large magne tic storms in 1998 are presented from the Polar Ionospheric X-ray Imaging E xperiment (PIXIE). The cross-polar-cap potential drop (Delta Phi (PC)) rema ined large (> 100 kV) throughout most of the stormtime periods, and most of the x-ray emissions observed were associated with enhanced earthward conve ction and dawnward drift of electrons caused by substantial cross-tail elec tric fields. Large increases in Delta Phi (PC) drove impulsive disturbances termed convection enhancements that showed signatures inconsistent with su bstorm activity, including substantial auroral emissions in the morning sec tor and Little activity in the premidnight sector.