Doppler investigations of the radar aurora at 400 mc

Abstract

By means of a relatively sensitive 400-Mc radar located at College, Alaska, the variation of Doppler shift of auroral echoes has been determined as a function of the following parameters: (1) azimuth angle of the radar ray; (2) off-perpendicular intersection angle of the radar ray and the earth's magnetic field; (3) elevation angle of the radar ray; (4) range of the echoes; (5) altitude of the reflection centers; (6) time of day; (7) number of occurrences; (8) strength of the echoes. These data have been further delineated in terms of the type of echo seen (discrete or diffuse) and whether the data were taken before or after magnetic midnight. An estimate of the spectrum spread of auroral echoes has also been determined by pulse and by CW techniques. A consistent trend in these data has been found which would indicate an east-west motion of the ionospheric irregularities. There is no appreciable variation in the direction of motion with time of day or with respect to magnetic midnight. The mean velocity of the east-west motion appears to be 500 meters per second. These conclusions agree with those of Kim and Curtie [1958] but disagree with those of Lyon and Kavadas [1958], Nichols [1957], and Bullough et al. [1957].