A Study of High Latitude Current Systems During Quiet Geomagnetic Conditions Using Magsat Data
- Thomas A. Potemra
Published Online: 21 MAR 2013
Copyright 1984 by the American Geophysical Union.
How to Cite
Burrows, J.R., Hughes, T.J. and Wilson, M. D. (1984) A Study of High Latitude Current Systems During Quiet Geomagnetic Conditions Using Magsat Data, in Magnetospheric Currents (ed T. A. Potemra), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM028p0104
- Published Online: 21 MAR 2013
- Published Print: 1 JAN 1984
Print ISBN: 9780875900551
Online ISBN: 9781118664131
- Magnetospheric currents—Congresses;
- Plasma instabilities—Congresses
Magsat has provided precise vector measurements of the geomagnetic field which have confirmed the large scale Birkeland current pattern observed earlier by higher altitude satellites such as TRIAD and ISIS 2. In addition to detecting Birkeland currents, MAGSAT's lower orbit (≈300–500 km) permits measurement of both ionospheric currents and crustal magnetic anomalies. The large scale Region 1 and 2 Birkeland currents, which are the dominant feature in the dawn and dusk sectors during moderate magnetic activity, tend to be replaced, during quiet magnetic periods, by structured, small scale current sheets throughout the polar region and by correspondingly reduced ionospheric electrojets. Several Magsat orbits across the dark, winter polar cap are quantitatively modelled. Total electrojet current intensities ranging from 1.8×104 A to 1.9×105 A are inferred along with ratios of zonal to meridional current densities ranging from 0.8 to 1.7. The extension of these modelling procedures to more structured current systems during very quiet magnetic condition is considered and a method of achieving better separation of crustal anomaly fields from external fields is proposed.