تقرير
What is the source of observed annual variations in plasmaspheric density?
| العنوان: | What is the source of observed annual variations in plasmaspheric density? |
|---|---|
| المؤلفون: | Guiter, S. M, Rasmussen, C. E, Gombosi, T. I, Sojka, J. J, Schunk, R. W |
| المصدر: | Journal of Geophysical Research. 100(A5) |
| بيانات النشر: | United States: NASA Center for Aerospace Information (CASI), 1995. |
| سنة النشر: | 1995 |
| مصطلحات موضوعية: | Geophysics |
| الوصف: | Plasmaspheric densities have been observed previously to be higher in December than in June, with the ratio varying between 1.5 and 3.0 and with larger variations at lower L shells. In order to search for the cause of the observed annual variations, we have modeled plasmaspheric density, using a time-dependent hydrodynamic model. On an L = 2 field line with geomagnetic longitude equal to 300 deg, the modeled plasmaspheric densities were a factor of 1.5 times higher in December than in June. The modeled December to June density ratio was found to increase slightly with L shell, in contrast to observations; this discrepancy may be due to the fact that outer plasmaspheric flux tubes are never completely full. In addition, for an L = 2 field line with geomagnetic longitude equal to 120 deg, the modeled plasmaspheric density was higher in June than in December by a factor of about 1.2. Various numerical tests were also performed in order to examine the sensitivity of plasmaspheric density to various parameters. In particular, a large vertical neutral wind was applied in order to raise the O(+) profile which had the effect of raising plasmaspheric density by a factor of 6. This in conjunction with a theoretical analysis suggests that plasmaspheric density levels are very sensitive to O(+) levels in the upper ionosphere. We conclude that annual variations in plasmaspheric density are due to similar variations in ionospheric O(+). |
| نوع الوثيقة: | Report |
| اللغة: | English |
| تدمد: | 0148-0227 |
| DOI: | 10.1029/94JA02866 |
| URL الوصول: | https://ntrs.nasa.gov/citations/19950058927 |
| ملاحظات: | NSF ATM-91-16858 NGT-50368 |
| رقم الأكسشن: | edsnas.19950058927 |
| قاعدة البيانات: | NASA Technical Reports |
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