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The determination of the diurnal variation of the auroral belt by radio means
Bates, Howard F.
Bates, Howard F.
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Abstract
Backscatter echoes in the high frequency portion of the radio spectrum exhibit a systematic southward movement in the evening and northward in the morning. Typically, the scattering belt lies about 78°N geomagnetic latitude during the day, and moves south to 65 to 70° at night. The extent of the southward movement correlates strongly with geomagnetic activity and, to a lesser degree, local time. No significant difference was found between summer and winter diurnal variations of the scattering belt. The scattering belt has been found to include the optical auroral belt; thus, it is concluded that there is no significant difference in the diurnal variation in the position of the summer and winter auroral belts for given levels of magnetic disturbance. The scattering belt was present on the College magnetic meridian during most of the two and one-half years’ observations. This is interpreted as showing the optical auroral belt existed most of the time somewhere on the College meridian, and hence on others as well. Thus, the auroral belt during the solar activity minimum period existed as a more or less closed curve around the geomagnetic pole. When the latitudinal effects are considered versus local time, the auroral belt takes the form of an oval curve, the northernmost portion approximately on the noon meridian. The size of the oval at any time is proportional to the size of the disturbance. The scattering belts as determined from simultaneous College and Thule backscatter soundings over approximately reciprocal paths generally coincided. This result shows that simultaneous soundings in four to eight directions from the magnetic pole could be used to map the auroral belt completely around the earth at any given time.
Description
UAG R-170; Scientific Report.
Date
1965-09
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Publisher
Geophysical Institute at the University of Alaska Fairbanks
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Keywords
Auroras, Radio waves, Scattering