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Fleck B, Carlsson M, Khomenko E, Rempel M, Steiner O, Vigeesh G. Acoustic-gravity wave propagation characteristics in three-dimensional radiation hydrodynamic simulations of the solar atmosphere. Philos Trans A Math Phys Eng Sci 2021; 379:20200170. [PMID: 33342376 DOI: 10.1098/rsta.2020.0170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/09/2020] [Indexed: 06/12/2023]
Abstract
There has been tremendous progress in the degree of realism of three-dimensional radiation magneto-hydrodynamic simulations of the solar atmosphere in the past decades. Four of the most frequently used numerical codes are Bifrost, CO5BOLD, MANCHA3D and MURaM. Here we test and compare the wave propagation characteristics in model runs from these four codes by measuring the dispersion relation of acoustic-gravity waves at various heights. We find considerable differences between the various models. The height dependence of wave power, in particular of high-frequency waves, varies by up to two orders of magnitude between the models, and the phase difference spectra of several models show unexpected features, including ±180° phase jumps. This article is part of the Theo Murphy meeting issue 'High-resolution wave dynamics in the lower solar atmosphere'.
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Affiliation(s)
- B Fleck
- ESA Science and Operations Department, c/o NASA/GSFC Code 671, Greenbelt, MD 20771, USA
| | - M Carlsson
- Rosseland Centre for Solar Physics, University of Oslo, Postboks 1029 Blindern, 0315 Oslo, Norway
- Institute of Theoretical Astrophysics, University of Oslo, Postboks 1029 Blindern, 0315 Oslo, Norway
| | - E Khomenko
- Instituto de Astrofísica de Canarias, La Laguna, 38205 Tenerife, Spain
- Departamento de Astrofísica, Universidad de La Laguna, La Laguna, 38205 Tenerife, Spain
| | - M Rempel
- High Altitude Observatory, NCAR, PO Box 3000, Boulder, CO 80307, USA
| | - O Steiner
- Leibniz-Institut für Sonnenphysik (KIS), Schöneckstrasse 6, 79104 Freiburg, Germany
- Istituto Ricerche Solari Locarno (IRSOL), Via Patocchi 57, 6605 Locarno-Monti, Switzerland
| | - G Vigeesh
- Leibniz-Institut für Sonnenphysik (KIS), Schöneckstrasse 6, 79104 Freiburg, Germany
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Abstract
In the lower solar atmosphere, the chromosphere is permeated by jets known as spicules, in which plasma is propelled at speeds of 50 to 150 kilometers per second into the corona. The origin of the spicules is poorly understood, although they are expected to play a role in heating the million-degree corona and are associated with Alfvénic waves that help drive the solar wind. We compare magnetohydrodynamic simulations of spicules with observations from the Interface Region Imaging Spectrograph and the Swedish 1-m Solar Telescope. Spicules are shown to occur when magnetic tension is amplified and transported upward through interactions between ions and neutrals or ambipolar diffusion. The tension is impulsively released to drive flows, heat plasma (through ambipolar diffusion), and generate Alfvénic waves.
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Affiliation(s)
- J Martínez-Sykora
- Bay Area Environmental Research Institute, Petaluma, CA 94952, USA. .,Lockheed Martin Solar and Astrophysics Laboratory (LMSAL), Palo Alto, CA 94304, USA
| | - B De Pontieu
- Lockheed Martin Solar and Astrophysics Laboratory (LMSAL), Palo Alto, CA 94304, USA.,Institute of Theoretical Astrophysics, University of Oslo, Post Office Box 1029, Blindern, N-0315 Oslo, Norway
| | - V H Hansteen
- Institute of Theoretical Astrophysics, University of Oslo, Post Office Box 1029, Blindern, N-0315 Oslo, Norway.,Lockheed Martin Solar and Astrophysics Laboratory (LMSAL), Palo Alto, CA 94304, USA
| | - L Rouppe van der Voort
- Institute of Theoretical Astrophysics, University of Oslo, Post Office Box 1029, Blindern, N-0315 Oslo, Norway
| | - M Carlsson
- Institute of Theoretical Astrophysics, University of Oslo, Post Office Box 1029, Blindern, N-0315 Oslo, Norway
| | - T M D Pereira
- Institute of Theoretical Astrophysics, University of Oslo, Post Office Box 1029, Blindern, N-0315 Oslo, Norway
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Abstract
We present a simple method to efficiently compute a lower limit of the topological entropy and its spatial distribution for two-dimensional mappings. These mappings could represent either two-dimensional time-periodic fluid flows or three-dimensional magnetic fields, which are periodic in one direction. This method is based on measuring the length of a material line in the flow. Depending on the nature of the flow, the fluid can be mixed very efficiently which causes the line to stretch. Here, we study a method that adaptively increases the resolution at locations along the line where folds lead to a high curvature. This reduces the computational cost greatly which allows us to study unprecedented parameter regimes. We demonstrate how this efficient implementation allows the computation of the variation of the finite-time topological entropy in the mapping. This measure quantifies spatial variations of the braiding efficiency, important in many practical applications.
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Affiliation(s)
- S Candelaresi
- Division of Mathematics, University of Dundee, Dundee DD1 4HN, United Kingdom
| | - D I Pontin
- Division of Mathematics, University of Dundee, Dundee DD1 4HN, United Kingdom
| | - G Hornig
- Division of Mathematics, University of Dundee, Dundee DD1 4HN, United Kingdom
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