Deciphering solar turbulence from sunspots records

Plunian, Franck; Sarson, Graeme R.; Stepanov, Rodion

doi:10.1111/j.1745-3933.2009.00760.x

Cited by 8 publications

(10 citation statements)

References 18 publications

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“…The spectrum between these two main periodicities is close to a power-law with the slope of about τ 2/3 . This is in a accordance with findings by Plunian et al (2009). We note that a power-law scaling is typical for various convective or turbulent systems.…”

Section: Results Of Wavelets Analysissupporting

confidence: 93%

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Spectral characteristic of mid-term quasi-periodicities in sunspots data

Frick,

Sokoloff,

Stepanov

et al. 2019

Preprint

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Numerous analyses suggest the existence of various quasi-periodicities in solar activity. The power spectrum of solar activity recorded in sunspot data is dominated by the ∼11-year quasi-periodicity, known as the Schwabe cycle. In the mid-term range (1 month -11 years) a pronounced variability known as a quasi-biennial oscillation (QBO) is widely discussed. In the shorter time scale a pronounced peak, corresponding to the synodic solar rotation period (∼ 27 days) is observed. Here we revisited the mid-term solar variability in terms of statistical dynamic of fully turbulent systems, where solid arguments are required to accept an isolated dominant frequency in a continuous (smooth) spectrum. For that, we first undertook an unbiased analysis of the standard solar data, sunspot numbers and the F10.7 solar radioflux index, by applying a wavelet tool, which allows one to perform a frequency-time analysis of the signal. Considering the spectral dynamics of solar activity cycle by cycle, we showed that no single periodicity can be separated, in a statistically significant manner, in the specified range of periods. We examine whether a model of solar dynamo can reproduce the mid-term oscillation pattern observed in solar data. We found that a realistically observed spectrum can be explained if small spatial (but not temporal) scales are effectively smoothed. This result is important because solar activity is a global feature, although monitored via small-scale tracers like sunspots.

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Section: Results Of Wavelets Analysissupporting

confidence: 93%

“…We understand it as possible isles of intermittent nature of solar dynamo. Strong intermittency was testified by calculating the corresponding scaling exponents in Plunian et al (2009). Perhaps, the scale of τ ≈ 2 years can be suggested as a timescale where intermittent effects are substantially pronounced.…”

Section: Results Of Wavelets Analysismentioning

confidence: 99%

Spectral characteristic of mid-term quasi-periodicities in sunspots data

Frick,

Sokoloff,

Stepanov

et al. 2019

Preprint

Self Cite

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“…The diffusion coefficient is also time-dependent, due to changes in the HMF turbulence (Manuel et al 2014). A basic diagnostic for the HMF turbulence is the manifestation of solar sunspots (Plunian et al 2009;Boschini et al 2017;Bobik et al 2012). Here, we adopt a simple two-coefficient relation κ 0 ≡ a + b log( Ŝ), where the Ŝ-function smoothly interpolates the monthly series of SSNs provided by the SIDC -Royal Observatory of Belgium (Clette & Lefevre 2016).…”

Section: Methodsmentioning

confidence: 99%

Evidence for a Time Lag in Solar Modulation of Galactic Cosmic Rays

Tomassetti

Orcinha

Barão

et al. 2017

ApJL

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The solar modulation effect of cosmic rays in the heliosphere is an energy-, time-, and particledependent phenomenon that arises from a combination of basic particle transport processes such as diffusion, convection, adiabatic cooling, and drift motion. Making use of a large collection of timeresolved cosmic-ray data from recent space missions, we construct a simple predictive model of solar modulation that depends on direct solar-physics inputs: the number of solar sunspots and the tilt angle of the heliospheric current sheet. Under this framework, we present calculations of cosmicray proton spectra, positron/electron and antiproton/proton ratios, and their time dependence in connection with the evolving solar activity. We report evidence for a time lag ∆T = 8.1 ± 1.2 months, between solar-activity data and cosmic-ray flux measurements in space, which reflects the dynamics of the formation of the modulation region. This result enables us to forecast the cosmic-ray flux near Earth well in advance by monitoring solar activity.

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“…In this paper, we try to go beyond the analysis of Plunian et al (2009). We analyse ISSN using our adapted version of SSA, to see whether the value of the slope of the density spectrum (DS) can be confirmed and, if so, refined, and whether its spectral domain of validity can be extended.…”

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confidence: 99%

Solar turbulence from sunspot records

Mouël

Lopes

Courtillot

2019

Monthly Notices of the Royal Astronomical Society

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It is generally assumed that coupling between the turbulent flow and the magnetic field at the top of the Sun's convection zone leads to a Kolmogorov cascade of kinetic to magnetic energy. An inertial range and a slope value close to −5/3 have been recognized in a log–log diagram of power spectral density versus frequency (or period). However, published values of the slope have large uncertainties and the inertial period range is limited to 0.1 s to 2 yr. We have applied an adapted version of the singular spectrum analysis (SSA) method to the series of (quasi-) daily sunspot numbers ISSN (an indirect way of monitoring solar activity) from 1868 to 2019. The log–log diagram of ISSN variance of SSA components versus frequency displays an inertial slope value of −1.66 ± 0.16 and an inertial range from about 4 to 100 yr. This is consistent with the existence of Kolmogorov turbulent behaviour in the Sun's convection zone.

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Deciphering solar turbulence from sunspots records

Cited by 8 publications

References 18 publications

Spectral characteristic of mid-term quasi-periodicities in sunspots data

Spectral characteristic of mid-term quasi-periodicities in sunspots data

Evidence for a Time Lag in Solar Modulation of Galactic Cosmic Rays

Solar turbulence from sunspot records

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