An analysis of micropulsation events at a low-latitude station during 1985
Abstract
Geomagnetic field fluctuations detected at L'Aquila ( L ∼ 1.6) during 1985 have been investigated on a statistical basis in the range of frequencies 7.8-234 mHz (Pc2, Pc3 and Pc4). The most significant events have been selected by means of a comparison between dynamic power spectra and the background spectrum. Dayside events, which perturb mainly the North-South component, tend to occur in two separate ranges, namely P1 = 25 ± 5 s, and P2 = 13 ± 2 s. The morphological differences between these groups of oscillations appear consistent with a wide source spectrum peaked at P1 (possibly upstream waves generated in the solar wind foreshock region) and a resonant mechanism at P2 which might correspond to the fundamental eigenperiod of the local field-line. Night-time events show all the characteristics of Pi2 pulsations and no evidence for field-line resonance phenomena is supported by the experimental observations.
- Publication:
-
Planetary and Space Science
- Pub Date:
- July 1989
- DOI:
- 10.1016/0032-0633(89)90128-1
- Bibcode:
- 1989P&SS...37..767V
- Keywords:
-
- Bow Waves;
- Geomagnetic Micropulsations;
- Power Spectra;
- Solar Wind;
- Tropical Regions;
- Earth Magnetosphere;
- Frequency Ranges;
- Resonance Lines;
- Statistical Analysis;
- Geophysics