Substorm injection of relativistic electrons to geosynchronous orbit during the great magnetic storm of March 24, 1991

Details Substorm injection of relativistic electrons to geosynchronous orbit during the great magnetic storm of March 24, 1991 Substorm injection of relativistic electrons to geosynchronous orbit during the great magnetic storm of March 24, 1991

Nov 2001

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2001jgr...10625759i&link_type=abstract

Journal of Geophysical Research, Volume 106, Issue A11, p. 25759-25776

Physics

12

Magnetospheric Physics: Energetic Particles, Trapped, Magnetospheric Physics: Magnetosphere-Outer, Magnetospheric Physics: Plasma Sheet, Magnetospheric Physics: Storms And Substorms

Scientific paper

The great March 1991 magnetic storm and the immediately preceding solar energetic particle event (SEP) were among the largest observed during the past solar cycle, and have been the object of intense study. We investigate here, using data from eight satellites, the very large delayed buildup of relativistic electron flux in the outer zone during a 1.5-day period beginning 2 days after onset of the main phase of this storm. A notable feature of the March storm is the intense substorm activity throughout the period of the relativistic flux buildup, and the good correlation between some temporal features of the lower-energy substorm-injected electron flux and the relativistic electron flux at geosynchronous orbit. Velocity dispersion analysis of these fluxes between geosynchronous satellites near local midnight and local noon shows evidence that both classes of electrons arrive at geosynchronous nearly simultaneously within a few hours of local midnight. From this we conclude that for this storm period the substorm inductive electric field transports not only the usual (50-300 keV) substorm electrons but also the relativistic (0.3 to several MeV) electrons to geosynchronous orbit. A simplified calculation of the electron E×B and gradient/curvature drifts indicates that sufficiently strong substorm dipolarization inductive electric fields (>~10 mV/m) could achieve this, provided sufficient relativistic electrons are present in the source region. Consistent with this interpretation, we find that the injected relativistic electrons have a pitch angle distribution that is markedly peaked perpendicular to the magnetic field. Furthermore, the equatorial phase space density at geosynchronous orbit (L=6.7) is greater than it is at GPS orbit at the equator (L=4.2) throughout this buildup period, indicating that a source for the relativistic electrons lies outside geosynchronous orbit during this time. Earthward transport of the relativistic electrons by large substorm dipolarization fields, since it is unidirectional, would constitute a strong addition to the transport by radial diffusion and, when it occurs, could result in unusually strong relativistic fluxes, as is reported here for this magnetic storm.

Affiliated with

Also associated with

No associations

Rating

Substorm injection of relativistic electrons to geosynchronous orbit during the great magnetic storm of March 24, 1991 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Substorm injection of relativistic electrons to geosynchronous orbit during the great magnetic storm of March 24, 1991, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Substorm injection of relativistic electrons to geosynchronous orbit during the great magnetic storm of March 24, 1991 will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-1555125