Two widely separated 50-MHz Doppler radars were used during April 1973 to simultaneously examine the diffuse radar aurora in a spatially limited common area. The permanent NOAA radar at Anchorage and a portable NOAA radar located at Aniak, Alaska, were operated with antennas having narrow beams that crossed north of College, Alaska, defining an area 40 km on a side. The two radars provided a unique measurement of aspect sensitivity, and a value of approximately 8 dB/deg was obtained with this system. The scattering cross section of the diffuse radar aurora was determined to be essentially the same at the two observing azimuths, which were separated by 43¿. In addition, Doppler spectra obtained at the two sites indicate that the diffuse radar auroral irregularities are similar in some respects to equatorial type 2 irregularities. However, in this experiment we find two distinct velocity components for the drifting irregularities. Both components maximize in the same direction but have significantly different magnitudes, a fact that the irregularities associated with these two Doppler components may be occurring at different altitudes. We have inferred a northward E region electric field of 20-30 mV/m from the crossed beam auroral radar data, while simultaneous measurements with the nearby Chatanika incoherent scatter radar indicated an inferred northward F region field component of about 50 mV/m. |