Tracking granules on the Sun's surface and reconstructing horizontal velocity fields: I. the CST algorithm
arXiv:0707.1991 · doi:10.1051/0004-6361:20066491
Abstract
Determination of horizontal velocity fields on the solar surface is crucial for understanding the dynamics of structures like mesogranulation or supergranulation or simply the distribution of magnetic fields. We pursue here the development of a method called CST for coherent structure tracking, which determines the horizontal motion of granules in the field of view. We first devise a generalization of Strous method for the segmentation of images and show that when segmentation follows the shape of granules more closely, granule tracking is less effective for large granules because of increased sensitivity to granule fragmentation. We then introduce the multi-resolution analysis on the velocity field, based on Daubechies wavelets, which provides a view of this field on different scales. An algorithm for computing the field derivatives, like the horizontal divergence and the vertical vorticity, is also devised. The effects from the lack of data or from terrestrial atmospheric distortion of the images are also briefly discussed.
in press in Astronomy and Astrophysics, 9 pages
References in corpus (2)
Cited by in corpus (21)
- On the power spectrum of solar surface flows
- Solar supergranulation revealed by granule tracking
- Quasi full-disk maps of solar horizontal velocities using SDO/HMI data
- Speed of Meridional Flows and Magnetic Flux Transport on the Sun
- Supergranulation and multiscale flows in the solar photosphere: Global observations vs. a theory of anisotropic turbulent convection
- Comparison of solar surface flows inferred from time--distance helioseismology and coherent structure tracking using HMI/SDO observations
- Large-scale horizontal flows in the solar photosphere III: Effects on filament destabilization
- Comparison of solar horizontal velocity fields from SDO/HMI and Hinode data
- The shrinking Sun: a systematic error in local correlation tracking of solar granulation
- Large-scale photospheric motions determined from granule tracking and helioseismology from SDO/HMI data
- Horizontal photospheric flows trigger a filament eruption
- Structure and evolution of solar supergranulation using SDO/HMI data
- Data compression for local correlation tracking of solar granulation
- Automated Solar Feature Detection for Space Weather Applications
- Dynamics of Trees of Fragmenting Granules in the Quiet Sun: Hinode/SOT Observations Compared to Numerical Simulation
- Tracking granules at the Sun's surface and reconstructing velocity fields. II. Error analysis
- Coronal kink oscillations and photospheric driving: combining SolO/EUI and SST/CRISP high-resolution observations
- Evolution of photospheric flows under an erupting filament in the quiet-Sun region
- Observational characterisation of large-scale transport and horizontal turbulent diffusivity in the quiet Sun
- One-sided arc averaging geometries in time-distance local helioseismology
- Automated detection of exploding granules with SDO/HMI data