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Title: Source for the geomagnetic storm main phase ring current

Journal Article · · J. Geophys. Res.; (United States)

It is shown that the flux increases of trapped ions and electrons observed by Explorer 45 at L< or =4 during two large geomagnetic stroms can be quantitatively explained by a 1--3 R/sub E/ inward radial displacement of the preexisting trapped particle distribution. This proposed source for the storm time ring current at L< or =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< or =4 is required. Is 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 displacement of the trapped particles can be explained by an equatorial electric field with an average azimuthal component of approx.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 (> or approx. =270 /sup 0/) longitude range during storms but only over a small (< or approx. =90 /sup 0/) longitude range during typical substorms.

Research Organization:
NOAA Space Environment Laboratory, Boulder, Colorado 80303
OSTI ID:
5391015
Journal Information:
J. Geophys. Res.; (United States), Vol. 85:A2
Country of Publication:
United States
Language:
English