| Autor: |
Efimov, A.I., Armand, N.A., Samoznaev, L.N., Bird, M.K., Chashei, I.V., Edenhofer, P., Plettemeier, D., Wohlmuth, R. |
| Předmět: |
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| Zdroj: |
AIP Conference Proceedings; 2003, Vol. 679 Issue 1, p469, 4p |
| Abstrakt: |
Frequency fluctuation temporal spectra measured during spacecraft radio occultation experiments are shown to have a maximum at a well defined temporal frequency if the density turbulence power spectrum of the solar wind has a power law form in the wavenumber range between the outer and inner turbulence scales. The frequency of this maximum and the associated maximal spectral power of the frequency fluctuations both depend on the density variance, the solar wind convection speed, the turbulence outer scale, and the power index of the density turbulence spectrum in the region of the propagation medium near the line-of-sight proximate point. If the solar wind speed can be estimated from simultaneous frequency fluctuation measurements at widely-spaced ground stations, then estimates can be derived for both the density turbulence outer scale and density variance from the measured values of the power exponent of the frequency fluctuation temporal spectra. Results of coronal radio sounding experiments in 1997 with the Galileo spacecraft were analysed using the above method. Distinct differences were found between the temporal frequency fluctuation spectra observed at large and at small heliocentric distances. Values of the fractional density variance in the solar wind at low heliolatitude during a period of low solar activity are presented for the range of heliocentric distances between 7 R⊙ and 31 R⊙. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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