Radar auroral echo characteristics as seen by a 398-MHz phased array radar operated at Homer, Alaska

Abstract

In this paper we present the first results of the mapping of the spatial distribution of auroral echoes by a 398-MHz phased array radar recently installed at Homer, Alaska. The results are shown in the form of two-dimensional spatial maps of auroral echoes. These maps are classified into types that are extensions of the ‘diffuse’ and ‘discrete’ echo types introduced by Leadabrand et al. (1959) and Presnell et al. (1959) for narrow beam radars. The auroral echo signatures typically seen during the afternoon and evening sectors are then described and discussed in relation to radar auroral echo characteristics found by previous investigations and other auroral processes. We show that interpretation of the occurrence of auroral echoes in terms of control by an electric field and by electron density in the radar scattering volume produces a consistent morphology of the radar aurora in relation to the other observed auroral processes. Finally, we include a dynamic auroral echo signature that may be related to the growth phase of an auroral substorm.