Correlation of radar echoes from the aurora with satellite-measured auroral particle precipitation

Abstract

A 139- and 398-Mhz auroral radar located at Homer, Alaska, was used to study the correlation between radar auroral echoes and the precipitating charged particles, as measured by a polar orbit satellite, producing the aurora. On the several satellite passes that showed on significant precipitating particles in the region that could be observed by the radar, no radar auroral echoes were obtained. On the one pass when both precipitating electrons and protons were detected by the satellite, the radar obtained auroral echoes that were most closely correlated in space with the >2-kev electrons, and no echoes were associated with the peak position of the >20-kev proton precipitation. The energy of the electrons measured is sufficient to produce ionization in the height region from which the echoes are obtained. The very close spatial relationship between the auroral echoes and the precipitating electrons indicates that for this particular case the primary generating mechanisms for the echo-producing auroral ionization are precipitating electrons.