Diffusion of Solar Magnetic Elements Up to Supergranular Spatial and Temporal Scales

Giannattasio, Fabio; Moro, D. Del; Berrilli, F.; Rubio, L. R. Bellot; ̆ić, M. Gos; Suárez, D. Orozco

doi:10.1088/2041-8205/770/2/l36

Cited by 33 publications

(64 citation statements)

References 71 publications

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“…This assumption has been verified in the quiet Sun Giannattasio et al 2013) where high values of β are observed. In a Lagrangian approach, the trajectories of single magnetic elements are employed for a statistical determination of the dynamical properties of the ensemble.…”

Section: Introductionmentioning

confidence: 62%

“…2 was realized by computing the displacement of magnetic elements from the long-duration (∼25 h) data set acquired by Hinode-NFI (Kosugi et al 2007;Tsuneta et al 2008) and used in the analysis by Giannattasio et al (2013Giannattasio et al ( , 2014a. The spatial resolution of this data set is 0.…”

Section: Real Datamentioning

confidence: 99%

“…The tracking algorithm used for the two data sets is the same used in Giannattasio et al (2013Giannattasio et al ( , 2014a and presented in Del Moro (2004) and Berrilli et al (2005). These two data sets combined allow us to explore more consistently the time range from 5 s to 10 000 s. They consistently identify a superdiffusive behaviour (γ 1.4) in the overlapping time range 90 s ≤ t < 500 s. We stress that, to our knowledge, this is the first time that two data sets acquired with rather different instruments and at different sites agree on retrieving γ values consistent within the errors.…”

Section: Real Datamentioning

confidence: 99%

“…Wang & Sheeley 1993;Schrijver et al 1996;Berger et al 1998;Hagenaar et al 1999;Chae et al 2008;Abramenko et al 2011;Chitta et al 2012;Giannattasio et al 2013Giannattasio et al , 2014aJafarzadeh et al 2014) at all accessible spatiotemporal scales, ranging from granulation (diameter 1 Mm and lifetime few minutes; Muller 1999;Hirzberger et al 1999;Del Moro 2004) to super-granulation (diameter 30 Mm and lifetime a day; Raju et al 1999;Srikanth et al 2000;Del Moro et al 2004). …”

Section: Introductionmentioning

confidence: 99%

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Super-diffusion versus competitive advection: a simulation

Moro

Giannattasio

Berrilli

et al. 2015

A&A

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Context. Magnetic element tracking is often used to study the transport and diffusion of the magnetic field on the solar photosphere. From the analysis of the displacement spectrum of these tracers, it has recently been agreed that a regime of super-diffusivity dominates the solar surface. Quite habitually this result is discussed in the framework of fully developed turbulence. Aims. However, the debate whether the super-diffusivity is generated by a turbulent dispersion process, by the advection due to the convective pattern, or even by another process is still open, as is the question of the amount of diffusivity at the scales relevant to the local dynamo process. Methods. To understand how such peculiar diffusion in the solar atmosphere takes place, we compared the results from two different data sets (ground-based and space-borne) and developed a simulation of passive tracers advection by the deformation of a Voronoi network.Results. The displacement spectra of the magnetic elements obtained by the data sets are consistent in retrieving a super-diffusive regime for the solar photosphere, but the simulation also shows a super-diffusive displacement spectrum: its competitive advection process can reproduce the signature of super-diffusion. Conclusions. Therefore, it is not necessary to hypothesize a totally developed turbulence regime to explain the motion of the magnetic elements on the solar surface.

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Section: Introductionmentioning

confidence: 62%

Section: Real Datamentioning

confidence: 99%

Section: Real Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Super-diffusion versus competitive advection: a simulation

Moro

Giannattasio

Berrilli

et al. 2015

A&A

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“…By analyzing the same data set, Giannattasio et al (2013) found that the equipartition magnetic flux density is B e 255 G. Only less than 4% of the total magnetic elements have an average flux greater than that value, and are all located in the network. Therefore, the condition of passive magnetic elements is reasonably fulfilled in the internetwork regions, as demonstrated by the spectro-polarimetric studies performed by Orozco Suárez et al As done in the previous works in the literature (see, e.g., Lepreti et al 2012) the separation spectrum Δr 2 was first computed for all the pairs of magnetic elements, regardless of their initial separation.…”

Section: Resultsmentioning

confidence: 99%

Pair separation of magnetic elements in the quiet Sun

Giannattasio¹,

Berrilli²,

Biferale³

et al. 2014

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The dynamic properties of the quiet Sun photosphere can be investigated by analyzing the pair dispersion of small-scale magnetic fields (i.e., magnetic elements). By using 25 h-long Hinode magnetograms at high spatial resolution (0. 3), we tracked 68 490 magnetic element pairs within a supergranular cell near the disk center. The computed pair separation spectrum, calculated on the whole set of particle pairs independently of their initial separation, points out what is known as a super-diffusive regime with spectral index γ = 1.55 ± 0.05, in agreement with the most recent literature, but extended to unprecedented spatial and temporal scales (from granular to supergranular). Furthermore, for the first time, we investigated here the spectrum of the mean square displacement of pairs of magnetic elements, depending on their initial separation r 0 . We found that there is a typical initial distance above (below) which the pair separation is faster (slower) than the average. A possible physical interpretation of such a typical spatial scale is also provided.

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Quiet Sun magnetic fields: an observational view

Rubio

Suárez

2019

Living Rev Sol Phys

119

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The quiet Sun is the region of the solar surface outside of sunspots, pores, and plages. In continuum intensity it appears dominated by granular convection. However, in polarized light the quiet Sun exhibits impressive magnetic activity on a broad range of scales, from the 30,000 km of supergranular cells down to the smallest magnetic features of about 100 km resolvable with current instruments. Quiet Sun fields are observed to evolve in a coherent way, interacting with each other as they are advected by the horizontal photospheric flows. They appear and disappear over surprisingly short time scales, bringing large amounts of magnetic flux to the solar surface. For this reason they may be important contributors to the heating of the chromosphere. Peering into such fields is difficult because of the weak signals they produce, which are easily affected, and even completely hidden, by photon noise. Thus, their evolution and nature remain largely unknown. In recent years the situation has improved thanks to the advent of high-resolution, high-sensitivity spectropolarimetric measurements and the application of state-of-the-art Zeeman and Hanle effect diagnostics. Here we review this important aspect of solar magnetism, paying special attention to the techniques used to observe and characterize the fields, their evolution on the solar surface, and their physical properties as revealed by the most recent analyses. We identify the main open questions that need to be addressed in the future and offer some ideas on how to solve them.

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Diffusion of Solar Magnetic Elements Up to Supergranular Spatial and Temporal Scales

Cited by 33 publications

References 71 publications

Super-diffusion versus competitive advection: a simulation

Super-diffusion versus competitive advection: a simulation

Pair separation of magnetic elements in the quiet Sun

Quiet Sun magnetic fields: an observational view

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