A source for the geomagnetic storm main phase ring current
Article first published online: 20 SEP 2012
Copyright © 1980 by the American Geophysical Union.
Journal of Geophysical Research: Space Physics (1978–2012)
Volume 85, Issue A2, pages 523–530, 1 February 1980
How to Cite
1980), A source for the geomagnetic storm main phase ring current, J. Geophys. Res., 85(A2), 523–530, doi:10.1029/JA085iA02p00523., and (
- Issue published online: 20 SEP 2012
- Article first published online: 20 SEP 2012
- Manuscript Accepted: 8 OCT 1979
- Manuscript Received: 28 FEB 1979
It is shown that the flux increases of trapped ions and electrons observed by Explorer 45 at L≤4 during two large geomagnetic storms can be quantitatively explained by a 1–3 RE inward radial displacement of the preexisting trapped particle distribution. This proposed source for the storm time ring current at L≤4 requires only the acceleration of the previously existing trapped particle population via inward displacement under conservation of the first two adiabatic invariants. No source of new trapped particles at L≤4 is required. It was not possible to test whether such an inward radial displacement can account for storm time flux increases at any radial distances beyond L=4; however, the existence of particle losses implies that new particles are injected into the trapping region beyond L=4. The required inward radial displacements of the trapped particles can be explained by an equatorial electric field with an average azimuthal component of ∼0.3–1.0 mV/m, which is a factor of 2 or 3 greater than electric fields observed within the plasmasphere in association with typical, nonstorm time, substorm activity. It is suggested that a significant difference between large geomagnetic storms and typical substorm activity may be inward convection occurring over a large (≳270°) longitude range during storms but only over a small (≲90°) longitude range during typical substorms.