CRRES observations of the composition of the ring-current ion populations

J. L. Roeder*, J. F. Fennell, M. W. Chen, M. Schulz, M. Grande, S. Livi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

38 Citations (SciVal)


The Magnetospheric Ion Composition Spectrometer onboard the CRRES spacecraft provided mass and charge state composition data for positive ions in the energy-per-charge range 10-425 keV/e. The CRRES data is compared to the AMPTE/CCE observations during both geomagnetically quiet and active periods. The CRRES average radial profiles of H+, He+, and He++ during quiet intervals are remarkably similar to those measured by CCE. The excess of ions measured by CRRES at L < 4 compared to standard ion transport models tends to support the necessity of additional ion radial diffusion by ionospheric electric-field variations. A summary is also given of the measured storm-time variations of the major ion populations during the large storm of March 1991. The results are compared to previous observations by the AMPTE/CCE spacecraft during a large storm. The CRRES data confirm that the rapid initial recovery of the Dst magnetic index is due to a momentary change of the relative ion composition of the ring current to an oxygen-dominated state. A preliminary test of the Dessler-Parker-Sckopke relation between the ion energy and the global magnetic perturbation shows that the observed particle fluxes during the March 1991 storm could account for only 30-50% of the variation of the Dst magnetic index.

Original languageEnglish
Pages (from-to)17-24
Number of pages8
JournalAdvances in Space Research
Issue number10
Publication statusPublished - 1996


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