How Will the Violation of Taylor's Hypothesis Alter the Turbulent Power Spectra Measured by Solar Probe Plus?
Abstract
Frequency measurements of magnetized turbulence obtained from in situ solar wind observations are a convolution of two terms; a spatial contribution from the sweeping of the solar wind structure past the observing spacecraft and a temporal contribution arising from the frequency of fluctuations in the frame of the plasma. For most observations at 1 AU, the super-Alfvenic nature of the solar wind allows us to adopt Taylor's hypothesis and neglect the plasma frame contribution to the measured frequency. Upcoming missions to measure solar wind turbulence in the near Sun environment, including Solar Probe Plus and Solar Orbiter, will not be able to neglect the plasma frame fluctuation term when the solar wind speed drops to near or below the Alfven speed. Motivated by these forthcoming observations, we make predictions concerning the effect that the violation of Taylor's hypothesis will have on measured magnetic power spectra. Critically balanced Alfven waves are shown to have negligible impact on the observed power spectra for reasonable solar wind speeds, while higher frequency fast/whistler waves are shown to distort the spectra in a predictable manner. Combining these results with near Sun observations should help to constrain the mechanisms responsible for generating, sustaining, and terminating the turbulent cascade in the solar wind.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2013
- Bibcode:
- 2013AGUFMSH51C2119K
- Keywords:
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- 7863 SPACE PLASMA PHYSICS Turbulence;
- 7827 SPACE PLASMA PHYSICS Kinetic and MHD theory