Interplanetary magnetic correlation and low-frequency spectrum over many solar rotations.

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Bibliographic Details
Title: Interplanetary magnetic correlation and low-frequency spectrum over many solar rotations.
Authors: Wang(王嘉明), Jiaming1, Pecora, Francesco1, Chhiber, Rohit1,2, Roy, Sohom1, Matthaeus, William H.1 whm@udel.edu
Source: Proceedings of the National Academy of Sciences of the United States of America. 1/6/2026, Vol. 123 Issue 1, p1-11. 11p.
Subjects: Interplanetary medium, Rotation of the Sun, Frequency spectra, Sun, Cosmic rays, Force & energy, Magnetic coupling, Pink noise
Abstract: Fluctuations and structure across a wide range of spatial and temporal scales are frequently studied in the solar wind. The properties of the low-frequency fluctuations are of relevance to turbulent energy injection into the plasma and the transport of highenergy cosmic rays. Correlation analysis of decade-long intervals of interplanetary data permits study of fluctuations at time scales much longer than suitably defined correlation times, and therefore at frequencies well below those associated with the Kolmogorov inertial range of in situ turbulence. At the frequencies of interest, we study the familiar occurrence of the 1/f spectral signature. We also study point spectral features due to solar rotation and their relation with the 1/f signal. We report properties at timescales ranging from minutes up to years, using data selected by wind speed, phase of solar cycle, and cartesian components of the magnetic field. A surprising finding is that the power in solar rotation harmonics is consistent with an extension of the 1/f spectrum, down to frequencies as low as around 5 × 10−7 Hz. The presence of a broadband 1/f spectrum across different wind types supports the interpretation that 1/f signals may be related to or even originate from the solar dynamo. [ABSTRACT FROM AUTHOR]
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Abstract:Fluctuations and structure across a wide range of spatial and temporal scales are frequently studied in the solar wind. The properties of the low-frequency fluctuations are of relevance to turbulent energy injection into the plasma and the transport of highenergy cosmic rays. Correlation analysis of decade-long intervals of interplanetary data permits study of fluctuations at time scales much longer than suitably defined correlation times, and therefore at frequencies well below those associated with the Kolmogorov inertial range of in situ turbulence. At the frequencies of interest, we study the familiar occurrence of the 1/f spectral signature. We also study point spectral features due to solar rotation and their relation with the 1/f signal. We report properties at timescales ranging from minutes up to years, using data selected by wind speed, phase of solar cycle, and cartesian components of the magnetic field. A surprising finding is that the power in solar rotation harmonics is consistent with an extension of the 1/f spectrum, down to frequencies as low as around 5 × 10−7 Hz. The presence of a broadband 1/f spectrum across different wind types supports the interpretation that 1/f signals may be related to or even originate from the solar dynamo. [ABSTRACT FROM AUTHOR]
ISSN:00278424
DOI:10.1073/pnas.2519811122