APPEARANCE OF ENHANCED VLF-EMISSIONS ON 8 KC/S OBSERVED ALONG A N-S CHAIN OF STATIONS

• Main Author: Harang,L.
• Other Authors: NORWEGIAN INST OF COSMIC PHYSICS UNIV OF OSLO
• Format: Text
• Language: English
• Published: 1966
• Subjects: Atmospheric Physics; (*ATMOSPHERICS; VERY LOW FREQUENCY); NORWAY; MAGNETIC STORMS; ELECTROMAGNETIC RADIATION; PROPAGATION; METEOROLOGICAL PHENOMENA; Norway; Tromso
• Online Access: http://www.dtic.mil/docs/citations/AD0640470; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=AD0640470

VLF-emissions on 8 kc/s have been recorded simultaneously along a chain of stations in N-S direction: Tromso, Lycksele, Oslo and Chambon la Foret, covering a latitude difference from 70 degrees to 48 degrees N. It is shown that the polar VLF-emissions recorded close to the auroral zone at Tromso during the night also can be traced on the records from Oslo with amplitudes of about 1/k00 - 1/500 of the Tromso amplitudes. A new type of VLF-emissions has been shown to appear at the stations Lycksele - Oslo, but not appearing at Tromso and Cambon la Foret. These low-latitude VLF-emissions appear during day time. There is thus a time difference of about 12 hours in the mean appearance of these two types of VLF-emissions. It is further pointed out that whereas the polar VLF-bursts appear during weak or moderate geomagnetic storms and in many cases a coincidence in details appears between the amplitudes of the VLF-bursts and the geomagnetic variations, the low-latitude emission appear in the day and start after the commencement of a great geomagnetic storm, usually 10-16 hours after the start. There are thus reasons to believe that the two types of VLF-emissions, the polar type recorded close to the auroral zone, and the low-latitude type recorded 5 degrees - 10 degrees to the south of the auroral zone are produced by different primary processes of excitation. (Author) See also AD-628 281.