Effects of Solar Activity on Taylor Scale and Correlation Scale in Solar Wind Magnetic Fluctuations

The correlation scale and the Taylor scale are evaluated for interplanetary magnetic field fluctuations from two-point, single time correlation function using the Advanced Composition Explorer (ACE), Wind, and Cluster spacecraft data during the time period from 2001 to 2017, which covers over an ent...

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Bibliographic Details
Published in:Astrophysical journal. Letters 2020-08, Vol.899 (2), p.L32
Main Authors: Zhou, G., He, H.-Q., Wan, W.
Format: Article
Language:English
Subjects:
Advanced Composition Explorer
Cluster spacecraft
Correlation coefficient
Correlation coefficients
Fluctuations
Fluid dynamics
Fluid flow
Interplanetary magnetic field
Interplanetary magnetic field fluctuations
Interplanetary medium
Interplanetary turbulence
Magnetic fields
Magnetic variations
Plasma turbulence
Solar activity
Solar cycle
Solar magnetic fields
Solar wind
Solar wind turbulence
Space plasmas
Spacecraft
Sunspot numbers
Sunspots
Time correlation functions
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Summary:The correlation scale and the Taylor scale are evaluated for interplanetary magnetic field fluctuations from two-point, single time correlation function using the Advanced Composition Explorer (ACE), Wind, and Cluster spacecraft data during the time period from 2001 to 2017, which covers over an entire solar cycle. The correlation scale and the Taylor scale are respectively compared with the sunspot number to investigate the effects of solar activity on the structure of the plasma turbulence. Our studies show that the Taylor scale increases with the increasing sunspot number, which indicates that the Taylor scale is positively correlated with the energy cascade rate, and the correlation coefficient between the sunspot number and the Taylor scale is 0.92. However, these results are not consistent with the traditional knowledge in hydrodynamic dissipation theories. One possible explanation is that in the solar wind, the fluid approximation fails at the spatial scales near the dissipation ranges. Therefore, the traditional hydrodynamic turbulence theory is incomplete for describing the physical nature of the solar wind turbulence, especially at the spatial scales near the kinetic dissipation scales.
ISSN:2041-8205
2041-8213
DOI:10.3847/2041-8213/abaaa9