Accession Number : AD0640470

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

Corporate Author : NORWEGIAN INST OF COSMIC PHYSICS UNIV OF OSLO

Personal Author(s) : Harang,L.

Report Date : 15 JUN 1966

Pagination or Media Count : 25

Abstract : 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)

Descriptors :   (*ATMOSPHERICS, VERY LOW FREQUENCY), NORWAY, MAGNETIC STORMS, ELECTROMAGNETIC RADIATION, PROPAGATION, METEOROLOGICAL PHENOMENA

Subject Categories : Atmospheric Physics

Distribution Statement : APPROVED FOR PUBLIC RELEASE