VLF Emissions Associated with Enhanced Magnetospheric Electrons.
Abstract
During periods of geomagnetic disturbances, VLF emissions and enhancements of low energy electrons are simultaneously observed by the equatorial orbiting Explorer 45 satellite. These events are characterized by the following features: (1) the VLF emissions occur outside the plasmasphere in the nightside of the magnetosphere; (2) the VLF emissions consist of two frequency regimes, one below the local electron gyrofrequency f sub-g and the other above f sub-g; (3) the VLF emissions below f sub-g are relatively broadband whistlermode waves characteristic of chorus and frequently have a conspicuous band of missing emissions near f sub-g. (4) the emissions above f sub-g are electrostatic and typically have components near 3f sub-g/2 and occasionally, higher frequency components are also observed; and (5) the onset of the emissions coincides with abrupt increases outside the plasmasphere (L greater than or equal to 4) in 1-10 keV electrons to intensities of the order of 10 to the 8-th power electrons/sq cm/sec/ster/keV; less pronounced enhancements sometimes occur for electrons with energies as high as 70 keV; and (6) the cessation of the emissions coincides with a drop in the electron intensities to their pre-enhancement levels which are of the order to 10 to the 6-th power electrons/sq cm/sec/ster/keV or less. This drop in low energy electron intensities occurs before or when the satellite crosses the plasmapause back into the plasmasphere.
Document Details
- Document Type
- Technical Report
- Publication Date
- Feb 01, 1976
- Accession Number
- ADA031354
Entities
People
- Kaichi Maeda
- Roger R. Anderson
Organizations
- University of Iowa