Auroral echoes observed north of the auroral zone on 51.9 mc/sec

Abstract

During November 1954, a simple radar system, designed for observation of auroral echoes at 51.9 Mc/sec, was operated at Point Barrow, Alaska. Because this location is north of the accepted maximum of the auroral zone, most of the visible aurora is seen to the south of the observing station. The radar used a continuously-rotating antenna to see with equal sensitivity in all directions, but more than 90 per cent of the echoes were obtained from directions north of east and west. Echoes were obtained only from 500 to 1100 km. These effects are explained by the theory of Moore as enlarged by Booker, Gartlein, and Nichols, requiring near-perpendicularity of radio ray paths to the lines of the earth's magnetic field. During visible aurora, propagation at 51.7 Mc/sec was investigated over an 800-km path from College to Barrow, across the auroral zone. Bursts of signal due to meteor ionization were readily observed. Propagation associated with aurora was almost non-existent, even with visible aurora at the mid-path. If the theory of auroral echoes of Harang and Landmark were true, auroral propagation should have been readily detected.