Quantitative relationships between plasma sheet fast flows and nightside auroral power

[1] In this study we quantitatively investigate auroral power rate of change during periods of plasma sheet fast flows. We first identify plasma sheet fast flows from Geotail plasma and magnetic field data and then estimate the rate of change in integrated auroral power over the nightside auroral region using Polar Ultraviolet Imager auroral images over the course of the fast flows. It is found that almost all tailward fast flows are associated with increasing auroral power. Half of earthward fast flows are associated with decreasing auroral power, indicating that the earthward fast flows are not necessarily associated with increasing auroral power. In addition, we quantitatively investigate relationships between the integrated nightside auroral power rate of change and average local magnetic field B-z at Geotail during fast flow periods. We find that almost all negative B-z events are associated with increasing auroral power. The integrated auroral power for positive B-z events increases and decreases almost equally often. Results derived from a further division of the earthward fast flows events at X = -20 R-E show that 67% of the earthward fast flows for X > -20 R-E are associated with increasing auroral power, but 54% of the earthward fast flows for X < -20 R-E are associated with decreasing auroral power. Moreover, percentage of earthward fast flows with increasing auroral power for the 2300-0100 MLT sector is significantly larger than those for other two local time sectors (2100-2300 and 0100-0300 MLT).