STARE: A new radar auroral backscatter experiment in northern Scandinavia

As part of the ground-based program for the International Magnetospheric Study (IMS), a new two-station VHF radar auroral experiment, STARE, has been constructed in northern Scandinavia. Each of these stations can provide good spatial and temporal resolution measurements of the intensity and Doppler velocity of radar auroral irregularities within a 300,000 km² scattering region. Approximately 230,000 km² of these scattering regions are common to both radars and within this area it is possible to compare the backscattered signals observed by the two radars and to combine the Doppler data to derive the mean irregularity drift velocity. The drift velocity can ultimately be related to the ionospheric electric field. In this paper we describe the operation of these radars and the method by which the data are processed. We also describe the assumptions used in the drift velocity analysis and present some initial measurements supporting their validity. Finally, we present several examples of the STARE data during two periods of counterstreaming currents in the late evening auroral oval. The irregularity drift patterns are consistent with the expected electron drift patterns for these periods and, from these patterns, one can determine the two-dimensional structure of the ionospheric electric field.