Spatial features of mid-latitude field-line resonances from simultaneous ground-satellite measurements
Three series of simultaneous pulsation measurements ( f <0.06 Hz) on the Freja satellite and at the Budkov Observatory have been spectrally processed (FFT) in 6-min intervals of Freja's transits near the local Budkov field line. Doppler-shifted, weighted spectral-peak frequencies, determ...
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| Published in: | Annales geophysicae (1988) Vol. 14; no. 7; pp. 699 - 706 |
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| Main Author: | |
| Format: | Journal Article |
| Language: | English |
| Published: |
Copernicus Publications
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| Online Access: | Get full text |
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| Summary: | Three series of simultaneous pulsation measurements ( f <0.06 Hz) on the Freja satellite and at the Budkov Observatory have been spectrally processed (FFT) in 6-min intervals of Freja's transits near the local Budkov field line. Doppler-shifted, weighted spectral-peak frequencies, determined in both transverse magnetic components in the mean field-aligned coordinate system on Freja, allowed the estimation, by comparison with the stable frequency at Budkov, of fundamental frequencies of the local magnetic-field-line resonance ranged from 13 to 17 mHz in two pulsation events analyzed, with K p =2 + to 0 + . The ratio of total amplitudes of the spectral-pulsation components on the ground and on Freja at an altitude of ~1700 km (values <0.7) characterizes the transmissivity of the ionosphere. In the Pc3 frequency range this correlates well with simulation computations using models of the ionosphere under low solar activity. |
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| ISSN: | 0992-7689 1432-0576 |