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

Global observations of the auroral x‐ray emissions during three large magnetic storms in 1998 are presented from the Polar Ionospheric X‐ray Imaging Experiment (PIXIE). The cross‐polar‐cap potential drop (ΔΦPC) remained large (>100 kV) throughout most of the stormtime periods, and most of the x‐ray emissions observed were associated with enhanced earthward convection and dawnward drift of electrons caused by substantial cross‐tail electric fields. Large increases in ΔΦPC drove impulsive disturbances termed convection enhancements that showed signatures inconsistent with substorm activity, including substantial auroral emissions in the morning sector and little activity in the premidnight sector.