Continuous Observation of the Auroral Belt by Means of Radio

THE purpose of this communication is to show that the southern edge of the auroral belt (the latitudinal range over which aurorae occur at a given time and longitude) can be reliably tracked by radio means. With the multi-frequency high-frequency system used at College, Alaska, the auroral belt can be tracked from overhead at 65° to above 80° north latitude. This wide coverage is possible because the high-frequency system utilizes ordinary ionospheric reflexion to extend the northern limit of detection, and normal E and F layer refraction to produce perpendicularity between the wave and the geomagnetic field. The very-high-frequency auroral radar, on the other hand, can detect only those aurorally associated scatterers located in the E layer near the relatively limited region where the line of sight is normal to the geomagnetic field.