STATISTICS CONCERNING THE APPEARANCE OF ENHANCED VLF-EMISSIONS ON 8 KC/S OBSERVED NEAR THE AURORAL ZONE OVER A TWO-YEAR PERIOD

• Main Author: Harang,L.
• Other Authors: NORWEGIAN INST OF COSMIC PHYSICS UNIV OF OSLO
• Format: Text
• Language: English
• Published: 1965
• Subjects: Atmospheric Physics; *ATMOSPHERICS; NORWAY; PROPAGATION; Norway; Tromso
• Online Access: http://www.dtic.mil/docs/citations/AD0628748; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0628748

The results of a two-year period, June 1963 - June 1965, of VLF-emission recordings on 8 kc/s at the Auroral Observatory at Tromso, near the northern auroral zone, is given. The annual curve of appearance of the bursts shows a pronounced variation with a maximum during winter time and a minimum during summer time. In the months November - February VLF-emissions are likely to appear daily for a period of about 1 hour. The diurnal curve shows that the VLF-emissions are limted to appear within the six hours interval 18 - 24 MET. The character of the annual and diurnal curves is explained as due to absorption within the lower part of the ionosphere: the annual absorption effect as due to solar control of the absorption process, the diurnal absorption effect is controlled mainly by the ionospheric absorption due to geomagnetic and auroral disturbances and the after-effects of these. (Author)