Vortex Flows in the Solar Chromosphere -- I. Automatic detection method

Abstract

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 such 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 for the mass and energy transport in the solar atmosphere. For this purpose, we have developed a new automatic detection method for chromospheric swirls, i.e. the observable signature of solar tornadoes or, more generally, chromospheric vortex flows and rotating motions. Unlike the previous studies that relied on visual inspections, our new method combines a line integral convolution (LIC) imaging technique and a scalar quantity which 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 3D 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 revealed very abundant small-scale, short-lived chromospheric vortex flows that had not been found by visual inspection before.

arXiv comment12 pages, 9 figures, accepted for publication in A&A

References in corpus (11)

• Simulations of stellar convection with CO5BOLD
• Numerical simulations of quiet Sun magnetism: On the contribution from a small-scale dynamo
• SUNRISE/IMaX observations of convectively driven vortex flows in the Sun
• Small-scale swirl events in the quiet Sun chromosphere
• Vortices, shocks, and heating in the solar photosphere: effect of a magnetic field
• Are giant tornadoes the legs of solar prominences?
• Vortices in simulations of solar surface convection
• The Role of Subsurface Flows in Solar Surface Convection: Modeling the Spectrum of Supergranular and Larger Scale Flows
• On the plasma flow inside magnetic tornadoes on the Sun
• First simultaneous SST/CRISP and IRIS observations of a small-scale quiet Sun vortex
• Convectively driven sinks and magnetic fields in the quiet Sun

Cited by in corpus (17)

• Three-dimensional Magnetohydrodynamic Simulation of the Formation of Solar Chromospheric Jets with Twisted Magnetic Field Lines
• The Alfvénic nature of chromospheric swirls
• Simulations Show that Vortex Flows could Heat the Chromosphere in Solar Plage
• Vortex Flow Properties in Simulations of Solar Plage Region: Evidence for their role in chromospheric heating
• A Comprehensive Radiative Magnetohydrodynamics Simulation of Active Region Scale Flux Emergence from the Convection Zone to the Corona
• Solar Vortex Tubes: Vortex Dynamics in the Solar Atmosphere
• Automated Swirl Detection Algorithm (ASDA) and Its Application to Simulation and Observational Data
• Stirring the Base of the Solar Wind: On Heat Transfer and Vortex Formation
• An innovative and automated method for vortex identification. I. Description of the SWIRL algorithm
• Vortices evolution in the solar atmosphere: A dynamical equation for the swirling strength
• Magnetic shocks and substructures excited by torsional Alfvén wave interactions in merging expanding flux tubes
• Co-spatial velocity and magnetic swirls in the simulated solar photosphere
• Chromospheric swirls I. Automated detection in H$\alpha$ observations and their statistical properties
• Influence of ambipolar and Hall effects on vorticity in 3D simulations of magneto-convection
• The non-ideal finite Larmor radius effect in the solar atmosphere
• On the 5-Minute Oscillations of Photospheric and Chromospheric Swirls
• Viscous Heating and Instabilities in the Partially Ionized Solar Atmosphere