Evolution of the ring current ion population, as observed by the CRRES/MICS instrument
- Rutherford Appleton Lab (United Kingdom)
- Aerospace Corp. (United States of America)
- Max Plank Institute fur Aeronomie (Germany)
Using the MICS instrument on CRRES, we have examined high charge state magnetospheric ions in the energy range 20{endash}400 keV/Q, believed to be originally solar wind material, as well as singly charged Oxygen and helium. We will present survey plots of MICS data from the whole CRRES mission. These show a number of interesting features. In particular, it can be seen that the generic feature of storm bulk ring current composition changes is the emergence of a concentration of ionospheric material at low ({ital L}=3) altitude, and its rise to higher {ital L}-shells during the recovery. By contrast, solar wind material remains preponderantly at higher {ital L}-shells, and a belt of ring current alphas forms around {ital L}=4. The altitude of the peak in ionospheric material is a strong function of {ital D}st. Substorms are seen to reflect the background composition at energization, with onset properties apparently unrelated to injection composition, but may contribute to the upflow of oxygen subsequent to onset. During the solar storm of March 1991 we see a considerable increase in the numbers of alpha particles, Fe, Si and other species. Simultaneous changes in their charge states are seen. For example, in the case of iron, we can recognize charge peaks around 9 and 16, and swings between the dominant charge state. The swings in other species charge states are consistent with a change in source temperature from 1.1 to 2.5 million degrees, as expected for different streams of coronal origin. It is clear that this material is locally trapped within the magnetosphere, which suggests that not only has there been an abrupt change between fast and slow stream material, but also that this signature has penetrated promptly to geostationary altitude. This hypothesis is to some extent confirmed by data from the GOES 7 satellite, which shows evidence of a sudden compression of the magnetosphere coincident with the start of the main period of high charge state material.
- OSTI ID:
- 453343
- Report Number(s):
- CONF-9408182-; ISSN 0094-243X; TRN: 97:006579
- Journal Information:
- AIP Conference Proceedings, Vol. 383, Issue 1; Conference: 10. Taos workshop on the earth`s trapped particle environment, Taos, NM (United States), 14-19 Aug 1994; Other Information: PBD: Jul 1996
- Country of Publication:
- United States
- Language:
- English
Similar Records
Crres observations of the composition of the ring-current ion populations
Oxygen charge state abundance in the inner magnetosphere