Journal article
The Amplitude of Magnetohydrodynamic Turbulence in the Inner Solar Wind
The Astrophysical journal, Vol.576(2), pp.997-1004
09/10/2002
DOI: 10.1086/341889
Abstract
Recent radio wave interplanetary scintillation observations have improved our knowledge of the level of turbulent fluctuations of plasma density in the inner solar wind at heliocentric distances of 16-26 R⊙ and less accurately outside this range. This information relates to fluctuations in the inertial subrange of the turbulence. Of particular concern in this paper is the heliocentric distance dependence of the power-law normalization parameter C N2. This measurement of CN2, when combined with independent measurements of the mean plasma density in the inner solar wind, indicates that the dimensionless amplitude of the turbulence ε ≡ σn/n̄ is low, of the order of 6%-15%, where σn is the standard deviation of the density fluctuations and n̄ is the mean value. The deduced value for ε depends on an assumed value for the outer scale of the turbulence, l0. I adopt a fiducial value of l0 = 1 R⊙. A comparison is made with independent estimates of ε, from both radio remote sensing in the same part of space and in situ measurements at greater distances. Satisfactory agreement occurs. I discuss the possibility that this dimensionless density amplitude ε might be a proxy for the corresponding amplitude of the magnetic field fluctuations. This is a controversial assertion. However, if it is the case, the measurements suggest that the turbulence in the inner solar wind is weak, in the sense of being dynamically and thermodynamically important.
Details
- Title: Subtitle
- The Amplitude of Magnetohydrodynamic Turbulence in the Inner Solar Wind
- Creators
- Steven R Spangler - University of Iowa
- Resource Type
- Journal article
- Publication Details
- The Astrophysical journal, Vol.576(2), pp.997-1004
- DOI
- 10.1086/341889
- ISSN
- 0004-637X
- eISSN
- 1538-4357
- Publisher
- University of Chicago Press
- Language
- English
- Date published
- 09/10/2002
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984199719902771
Metrics
14 Record Views