Substorm-related VLF chorus events: Local-time dependence and relationship to newly-injected clouds of drifting energetic electrons
Abstract
VLF chorus, a naturally occurring, electromagnetic wave phenomenon generated in the Earth's magnetosphere during interactions between VLF waves and energetic electrons was studied. The macrostructure of a 9 day period of VLF ground station data, recorded at two antarctic stations was studied using compressed time scale spectrograms. A magnetically quiet period was chosen for analysis, within which isolated substorms occurred. It was found that chorus frequently occurs in events, the most characteristic feature of which is an initial rise in the upper cut off frequency of the chorus band. Two interpretations of the chorus events were investigated based on the time dependence theory. The first model suggests that the observed rise in frequency is due to an inward convection of a bunch of electrons under a substorm enhanced westward electric field. The second model suggests that the dispersion is responsible for the time evolution of the events.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- February 1979
- Bibcode:
- 1979PhDT........43T
- Keywords:
-
- Dawn Chorus;
- High Energy Electrons;
- Magnetic Storms;
- Time Dependence;
- Very Low Frequencies;
- Earth Magnetosphere;
- Electron Clouds;
- Electron Energy;
- Magnetic Fields;
- Mathematical Models;
- Communications and Radar