2017/02/20 by Yoshiaki Kato, Y. Kato, Sven Wedemeyer · 39 citations
Computer Science · Engineering · Physics and Astronomy · #Atmosphere (unit) #Chromosphere #Fluid Dynamics and Turbulent Flows #Magnetic field #Mechanics #Meteorology #Photosphere #Physics #Solar Radiation and Photovoltaics #Solar and Space Plasma Dynamics #Solar irradiance #Vortex #Vorticity #astro-ph.SR
paper · pdf · doi:10.1051/0004-6361/201630082
published in Astronomy and Astrophysics 601, A135 (EDP Sciences) · 12 pages, 9 figures, accepted for publication in A&A
arxiv created 2017/02/20 · openalex publication_date 2017/03/17 · arxiv updated 2017/05/24 · openalex created_date 2022/09/19 · openalex updated_date 2026/08/01
Solar “magnetic tornadoes” are produced by rotating magnetic field structures that extend from the upper convection zone and the photosphere to the corona of the Sun. Recent studies show that these kinds of rotating features are an integral part of atmospheric dynamics and occur on a large range of spatial scales. A systematic statistical study of magnetic tornadoes is a necessary next step towards understanding their formation and their role in mass and energy transport in the solar atmosphere. For this purpose, we develop a new automatic detection method for chromospheric swirls, meaning the observable signature of solar tornadoes or, more generally, chromospheric vortex flows and rotating motions. Unlike existing studies that rely on visual inspections, our new method combines a line integral convolution (LIC) imaging technique and a scalar quantity that represents a vortex flow on a two-dimensional plane. We have tested two detection algorithms, based on the enhanced vorticity and vorticity strength quantities, by applying them to three-dimensional numerical simulations of the solar atmosphere with CO5BOLD. We conclude that the vorticity strength method is superior compared to the enhanced vorticity method in all aspects. Applying the method to a numerical simulation of the solar atmosphere reveals very abundant small-scale, short-lived chromospheric vortex flows that have not been found previously by visual inspection.