Vortex Flows in the Solar Atmosphere: Automated Identification and Statistical Analysis

Abstract

Aims. Due to the fundamental importance of vortices on the photosphere, in this work we aim to fully automate the process of intensity vortex identification to facilitate a more robust statistical analysis of their properties. Methods. Using on-disk observational data of the Fe i continuum, the process of vortex identification is fully automated, for the first time in solar physics, with the help of an established method from hydrodynamics initially employed for the study of eddies in turbulent flows (Graftieaux et al. 2001).Results. We find that the expected lifetime of intensity vortices is much shorter (≈ 17s) compared with previously observed magnetic bright point swirls. Our findings suggest that at any time there are 1.4 × 10 6 such small-scale intensity vortices covering about 2.8% of the total surface of the solar photosphere.

Solar Vortex Tubes: Vortex Dynamics in the Solar Atmosphere

“…Vortical flows in the photosphere have been investigated using velocity fields derived from both observations (Bonet et al 2010;Attie et al 2009;Bonet et al 2008;Balmaceda et al 2010;Giagkiozis et al 2018;Requerey et al 2018;Tziotziou et al 2018Tziotziou et al , 2019Shetye et al 2019) and magnetohydrodynamics (MHD) simulations (see e.g. Kitiashvili et al 2012b;Moll et al 2012;Wedemeyer-Böhm et al 2012;Wedemeyer & Steiner 2014;Kato & Wedemeyer 2017).…”

Converging photospheric vortex flows close to the polarity inversion line of a fully emerged active region

“…The conservation of angular momentum forces the plasma to rotate around the center of the downdraft, generating small-scale vortexes. These vortexes have been extensively detected in observations of the photosphere (Brandt et al, 1988;Simon and Weiss, 1997;Attie et al, 2009;Bonet et al, 2010;Balmaceda et al, 2010;Vargas Domínguez et al, 2011) and also have been observed in the quiet Sun chromosphere as a signature of plasma moving along curly magnetic field lines in coronal holes (Wedemeyer-Böhm and Rouppe van der Voort, 2009). Simulations indicate that the vortexes occurring in strongly magnetized regions are closely connected with dissipation processes providing localized heating in the lower parts of the solar atmosphere (Moll et al, 2012), and observations usually associate vortex detection with bright points (Bonet et al, 2008).…”

“…Unfortunately, there are some issues regarding the LCT-FLCT method. As pointed by Démoulin and Berger (2003), if the flux tube is inclined when it rises through the solar atmosphere, the point where it crosses the photosphere moves horizontally. This apparent motion can be interpreted by the LCT-FLCT method as a proper horizontal motion, and Démoulin and Berger (2003) suggested a correction if the tangential component of the magnetic field and the vertical component of the velocity are known.…”

“…Photospheric vortexes are important, since they can form twisted flux tubes, transporting magnetic energy and helicity to upper layers of the solar atmosphere in the process. They are usually detected by visual inspections and, since this may cause a bias in the analysis of vortexes, efforts in developing automated detection methods have been recently performed (Kato and Wedemeyer, 2017;Rempel et al, 2017;Giagkiozis et al, 2018). In this work, we intend to contribute to the development of automated methods of vortex detection by using a well-known method of detection and classification of critical points (Helman and Hesselink, 1989) to identify converging vortexes by associating them with a specific kind of critical point.…”

“…On larger scales, rotational motions were observed in sunspots, and they are usually associated with energy and helicity buildup and later release by flare and/or coronal mass ejection (Brown et al, 2003;Hiremath and Suryanarayana, 2003;Hiremath et al, 2005;Yan and Qu, 2007;Yan et al, 2008Yan et al, , 2009Yan et al, , 2012Min and Chae, 2009;Kazachenko et al, 2010;Zhu et al, 2012;Jiang et al, 2012;Vemareddy et al, 2012Vemareddy et al, , 2016Hardersen et al, 2013;Wang et al, 2014Wang et al, , 2016Ruan et al, 2014;Gopasyuk, 2015;Li and Liu, 2015;Suryanarayana et al, 2015). The rotation of sunspots is usually very slow; this means that the evolution of the magnetic field in the corona associated with it would be slow as well.…”