Giant PC5 pulsations in the outer magnetosphere: A survey of HEOS-1 data
Abstract
Magnetic field measurements from 133 low-latitude transits of the HEOS-1 satellite through the magnetosphere have been used to analyse the low-frequency pulsation activity in the outer regions of the geomagnetic field. Providing full longitude coverage in the sunward hemisphere at geocentric distances larger than ~7.5 Re, this survey complements previous low-frequency pulsation data from satellites at smaller geocentric distances. Several giant PC5 events, each being mainly compressional and lasting 1-2 hr, are described in detail and it is shown that this phenomenon is relatively common in the 8-12 Re, geocentric distance range near dusk. A depression of the ambient field magnitude always accompanied the events, suggesting that they are associated with a region of enhanced plasma pressure. The properties of these wave events are compared with the predictions of current micropulsation theories involving a Kelvin-Helmholtz generation mechanism and field-line resonance. Unlike the PC5 events observed nearer Earth, these events were not obviously related to periods of enhanced geomagnetic activity.
- Publication:
-
Planetary and Space Science
- Pub Date:
- October 1976
- DOI:
- 10.1016/0032-0633(76)90003-9
- Bibcode:
- 1976P&SS...24..921H
- Keywords:
-
- Earth Magnetosphere;
- Geomagnetic Pulsations;
- Heos Satellites;
- Magnetic Measurement;
- Propagation Modes;
- Ats 1;
- Data Processing;
- Magnetic Dipoles;
- Magnetic Field Configurations;
- Magnetic Signatures;
- Magnetopause;
- Plasma Pressure;
- Satellite-Borne Instruments;
- Geophysics