Evolution and advection of solar mesogranulation

Müller, R.; Auffret, H.; Roudier, T.; Vigneau, J.; Simon, Gilles; Frank, Z.; Shine, R. A.; Title, A. M.

doi:10.1038/356322a0

Cited by 55 publications

(52 citation statements)

References 19 publications

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“…The advective motion of MGs towards the borders of the supergranulation was first described by Muller et al (1992). Also DeRosa & Toomre (1998, 2004 found convincing evidence in their results from SOHO/MDI Dopplergrams that MGs are advected by the supergranulation.…”

Section: Introductionmentioning

confidence: 62%

“…Table 1 shows that most previous determinations came up with shorter lifetimes than those of SSH, ranging from 30-40 min (Deubner 1989;Ueno & Kitai 1998;Roudier et al 1998) to 1-2 h (November et al 1981) to 3 h (Muller et al 1992). However, one should not forget the very different data material, analysis and filtering methods involved in the various measurements.…”

Section: Lifetimementioning

confidence: 99%

“…The data were from SSH in the form of flow fields derived from a local correlation tracking process (for details see SSH and below) -but needed some further processing in order to be suited for the feature tracking mentioned above. Deubner (1989) ≥30 min 450 Muller et al (1992) 3 h 300−400 Ueno & Kitai (1998) 40 min 446 Roudier et al (1998) 30−40 min 500 (t ≥ 70min) Ploner et al (2000) 1−2 h − Shine et al (2000) 4−6 h 500−1000 present work 158 min 304…”

Section: Introductionmentioning

confidence: 99%

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Dynamics of solar mesogranulation

Leitzinger

Brandt

Hanslmeier

et al. 2005

A&A

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Using a 45.5-h time series of photospheric flow fields generated from a set of high-resolution continuum images (SOHO/MDI) we analyze the dynamics of solar mesogranule features. The series was prepared applying a local correlation tracking algorithm with a 4.8 FWHM window. By computing 1-h running means in time steps of 10 min we generate 267 averaged divergence maps that are segmented to obtain binary maps. A tracking algorithm determines lifetimes and barycenter coordinates of regions of positive divergence defined as mesogranules (MGs). If we analyze features of lifetimes ≥1 h and of areas ≥5 Mm 2 we find a mean drift velocity of 304 m s −1 (with ±1σ variation of 180 m s −1 ), a mean travel distance of 2.5 ± 1.8 Mm, a mean lifetime of 2.6 ± 1.8 h, and a 1/e decay time of 1.6 h for a total of 2022 MGs. The advective motion of MGs within supergranules is seen for 50 to 70% of the long-lived (≥4 h) MGs while the short-lived ones move irregularly. If only the long-lived MGs are further analyzed the drift velocities reduce to 207 m s −1 and the travel distances increase to 4.1 Mm on average, which is an appreciable fraction of the supergranular radius. The results are largely independent of the divergence segmentation level.

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Section: Introductionmentioning

confidence: 62%

Section: Lifetimementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dynamics of solar mesogranulation

Leitzinger

Brandt

Hanslmeier

et al. 2005

A&A

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“…Roudier, e-mail: roudier@bagn.obs-mip.fr On the one hand, low resolution measurements of the properties of solar photospheric flows support the existence of different convective scales. In particular, the work of Muller et al (1992) and Shine et al (2000) shows the persistence of the supergranulation, and the motion of the mesogranules toward the supergranular boundaries in accordance with the model of Simon et al (1991). On the other hand, Rieutord et al (2000) found that computing the flow fields with high spatial (0.7 ) and temporal resolution (5 min) reveals the important role of the strong positive divergences (SPDs) in forming the larger scales (meso-and supergranulation).…”

Section: Introductionmentioning

confidence: 99%

Families of fragmenting granules and their relation to meso– and supergranular flow fields

Roudier

Lignières

Rieutord

et al. 2003

A&A

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Abstract. 3D analysis (x, y, t) of the granular intensity field (11-hour time sequence from the Swedish Vacuum Solar Telescope on La Palma, Canary Islands), demonstrates that a significant fraction of the granules in the photosphere are organized in the form of "Trees of Fragmenting Granules" (TFGs). A TFG consists of a family of repeatedly splitting granules, originating from a single granule at its beginning. A striking result is that TFGs can live much longer (up to 8 h) than individual granules (10 min). We find that 62% of the area covered by granules belongs to TFGs of a lifetime >1.5 h. When averaged in time, such long-lived TFGs correspond to coherent diverging flows which may be identified as mesogranules. We also find a correlation between the network and the spatial distribution of TFGs.

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“…Mesogranular patterns appear in divergence maps of horizontal flows inferred by local correlation tracking of tracers, such as granules and magnetic flux concentration (November 1989;Muller et al 1992;Roudier et al 1998;Shine et al 2000). Associated intensity variations on the same scales have not been found.…”

Section: Introductionmentioning

confidence: 99%

Modelling of solar mesogranulation

Matloch

Cameron

Schmitt

et al. 2009

A&A

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We study whether mesogranulation flow patterns at the solar surface can arise solely from the statistical properties of granules and intergranular lanes. We have developed one-and two-dimensional models with local interaction rules between the artificial "granules" mimicking the actual physical processes on the solar surface. Defining mesogranulation according to the age of intergranular (downflow) lanes corresponding to the often applied "cork method", as well as the areas of divergence of the horizontal velocity (two-dimensional model), we find that mesogranular patterns are present in our models. Our study of the dependence of the properties of the mesogranular patterns on the model parameter and interaction rules reveals that the patterns do not possess intrinsic length and time scales.

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Evolution and advection of solar mesogranulation

Cited by 55 publications

References 19 publications

Dynamics of solar mesogranulation

Dynamics of solar mesogranulation

Families of fragmenting granules and their relation to meso– and supergranular flow fields

Modelling of solar mesogranulation

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