VLF EMISSIONS DURING MAGNETIC STORMS AND THEIR ASSOCIATION WITH 40 keV ELECTRONS,
Abstract
Spectrograms of very low frequency radio noise recorded by University of Iowa satellite Injun 3 at invariant latitudes greater than 50N are used to determine the behavior of VLF emissions during magnetic storms. Variations in the wideband intensity of VLF emissions from L = 3 to L = 8 are studied for the period from 28 April to 28 August 1963 by means of the automatic gain control levels of the satellite VLF receiver. During a sudden-commencement magnetic storm the VLF emission called polar chorus characteristically appears at the onset of the storm, may increase in upper frequency extent to approximately 5 kHz, may change from spike to burst structure (normal chorus), and occurs over the greatest area on the fourth day of the storm, subsequently fades into low frequency, spike-structure polar chorus again and eventually disappears into the ELF hiss band generally present. Chorus occurrence shows symmetry about the 9:00 - 21:00 magnetic local time meridian with a large maximum in magnetic morning and a smaller maximum in magnetic evening. Daily regions of occurrence are shown for the duration of a prototypical storm. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1968
- Accession Number
- AD0676887
Entities
People
- David P. Cauffman
- Donald A. Gurnett
Organizations
- University of Iowa