Large-scale fluctuations in the interplanetary medium
| Autor: | W. H. Mish, L. F. Burlaga |
|---|---|
| Rok vydání: | 1987 |
| Předmět: |
Physics
Atmospheric Science Ecology Paleontology Soil Science Interplanetary medium Forestry Astrophysics Aquatic Science Oceanography Power law Magnetic flux Spectral line Magnetic field Geophysics Space and Planetary Science Geochemistry and Petrology Earth and Planetary Sciences (miscellaneous) Exponent Cutoff Atomic physics Heliosphere Earth-Surface Processes Water Science and Technology |
| Zdroj: | Journal of Geophysical Research. 92:1261 |
| ISSN: | 0148-0227 |
| DOI: | 10.1029/ja092ia02p01261 |
| Popis: | Power spectra of measurements of the magnetic field strength in the heliosphere obtained by Voyager 1 between 1 AU and 9 AU have the form of a power law f exp -a from periods of several hours to at least 6 days. The exponent was a = 2.0 + or - 0.05 for all of the spectra considered, which is the exponent for a series of steps and for Burgers' (1971) turbulence. Spectra of large-scale speed fluctuations also have the form f exp - b from a period of a few hours to periods greater than 13 days in the region from 1 AU to 8.9 AU. The exponent b is generally somewhat larger than b = 2, implying some 'persistence' of the speed fluctuations. The low-frequency cutoff (outer cutoff) of the power law increases from a period of 6.5 days at 1 AU to 26 days at (6.1-8.9) AU, which can be attributed to: (1) the coalescence of interaction regions and (2) a transfer of energy from the spectrum of large-scale speed fluctuations. The outer cutoff of the spectrum of speed fluctuations increases from a period of 13 days at 1 AU to 26 days between a few AU and 8.9 AU. Both the magnetic field strength fluctuations and the speed fluctuations have fractal behavior, suggesting that they are self affine rather than dominated by a few large discontinuities. |
| Databáze: | OpenAIRE |
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