On the Identification of the Dayside Auroral Region Using Incoherent Scatter Radar

Abstract

This paper presents a robust method combining electron temperatures and density to identify the winter dayside auroral region in Incoherent Scatter Radar (ISR) observations. In literature, a common proxy for identifying the dayside auroral region has been enhanced electron temperatures T_e at high altitudes. However, T_e is intimately related to N_e and their relationship is not completely settled. In this study, the relation between T_e, N_e, and the precipitation heat source Q is quantified. Using ESR fast elevation scans in the winter dayside auroral region, the intimate relationship between these three parameters is investigated. T_e decreases roughly linearly with exponentially increasing N_e, irrespective of the heat source. Precipitation creates a heated population with T_e above roughly 2,000 K (i.e., 500–1,300 K higher than the background plasma). Several extensions to the purely T_e based method were examined, and it is found that combining T_e and N_e yields consistent boundaries when compared to magnetic disturbance data from Swarm satellites and 6,300 Å auroral observations. Future applications of characterizing ionospheric dynamics are discussed.