Programme

Dates: 2–4 June 2025

Location: The meeting will be held at the University of Sheffield, Mappin Building, Room E125a

02/06/2025- Monday

Morning Session- Observations

09:00 - 09:40

09:40 - 10:30

Discussions: “Observing Solar Vortices: Where Are We Now?”

10:30 - 11:00 Coffee break 

11:00 - 11:30

Investigation of the kinematics and dynamics of swirling structures of the solar atmosphere using high resolution observations and their effect on the corresponding spectral line profiles 

Ioannis Dakanalis, Georgia Tsiropoula, Kostas Tziotziou

IAASARS/NOA, Greece

Abstract: Vortical structures have recently proven to be ubiquitous on the sun manifesting themselves with various observational signatures in the different layers of the solar atmosphere. Using observations of the Halpha, Ca II 8542 Angstrom and Ca II K spectral lines obtained by the CRISP and CHROMIS instruments of the Swedish 1-m Solar Telescope (SST), which map a wide range of heights from the photosphere to the upper chromosphere, we investigate these signatures and their morphological imprint, as well as, the absorption of the intensity line profiles on the various spectral regions. In addition, we perform an extensity analysis on the intensity profiles of the observed swirling structures (shape, behavior of spectral line widths, contrast profiles), deriving significant physical properties in the process (proxies of temperature, velocities, velocity gradients, proxies of absorption) towards the investigation of their kinematics and dynamics. 

11:30 - 13:00

       Discussions: “The State of Vortex Dynamics: Lessons from Observations”

13:00 - 14:00 Lunch

Afternoon Session - Vortex Identification

14:00 - 14:30

On the reliability of Local Correlation Tracking for inferring photospheric vortex flows in high-resolution observations

Shivdev Turkay (1), Eamon Scullion (1), Gert Botha (1), Thomas Rees-Crockford (1,2)

1 Northumbria University, UK 

2 KU Leuven, Belgium

Abstract: Vortex flows in the solar photosphere are ubiquitous and are thought to inject energy into the upper solar atmosphere in the form of Poynting flux. However, observing photospheric intensity vortices is challenging due to their small size and the fact that the flow field is primarily parallel to the plane-of-sky. Despite this, a large number of photospheric intensity vortices have been observed by applying Fourier Local Correlation Tracking (FLCT) to high-resolution observations. Validating these detections raises two questions: i) Are changes in photospheric intensity a suitable proxy for tracking the plasma velocity field? ii) Are the statistics on the observed properties of photospheric vortices accurate, given a significant number of vortices are considered to remain unresolved by most instruments? To address these questions, we compare observations from the Daniel K. Inouye Solar Telescope (DKIST) with a synthetic observation produced by a radiative magnetohydrodynamic MURaM simulation. We employ FLCT to infer the velocity field from the observations and use the $\Gamma$-functions method to identify and track the properties of vortices therein. We find a discrepancy between the number of vortices identified in the DKIST observation, the synthetic observation, and the plasma properties derived from the simulation. Here, we compare the simulated and inferred velocity fields and outline the potential implications of the validity of FLCT. This research draws important conclusions on the photospheric intensity vortices with further consequences on the expected energy transfer to the upper solar atmosphere.

14:30 - 15:00

Spotting Swirls in the Solar Chromosphere

Matthew Lennard (1), Suzana Silva (1), Shahin Jafarzadeh (2), Gary Verth (1), Istvan Ballai (1), Viktor Fedun (1)

1 University of Sheffield, UK

2Queen's University Belfast, UK

Abstract: Transport between layers of the solar atmosphere is generally attributed to two main mechanisms–magnetoacoustic waves and advection via plasma flow. Understanding the transport of material across the solar surface via flows has been an active field of research both in modelling and observations thanks to high resolution simulations of the photosphere and velocity tracking methods such as local correlation tracking (LCT) techniques. However, the complexity of the non-LTE nature of the chromosphere has meant modelling has only recently been made feasible, and identification of flow features such as coherent vortices still remains a challenge for the future. Recent works have proven the DeepVel (DV) neural network to be capable of correctly reconstructing small-scale and transient coherent structures in the photosphere. In this talk I present the findings of training DV on simulations of the Chromosphere. By utilising non-LTE methods to synthesise images, the network was able to generate velocity fields and reproduce coherent swirling structures in the upper atmosphere of the Sun and vortex detection was used to analyse the success of the method.

15:00 - 15:40 Coffee break

15:40 - 16:40

Discussion: “Velocity recovery and vortex detection methods”

Icebreaker afterwards

03/06/2025- Tuesday

Morning Session - Vortex and plasma heating

09:00 - 09:30

3D MHD wave propagation and energy transport in a simulated solar vortex

Samuel Skirvin (2,1), Fedun Viktor (1), Verth Gary (1), Ballai Istvan (1)

1 University of Sheffield, UK 

2 Queen's University Belfast, UK

Abstract: Magnetic flux tubes in the presence of background rotational flows are abundant throughout the solar atmosphere and may act as conduits for MHD waves to transport energy throughout the solar atmosphere. This study investigates the contribution from MHD waves to the Poynting flux in a 3D numerical simulation of a solar vortex tube, using the PLUTO code. The simulations feature a closed magnetic loop system where a rotational flow is imposed at one foot-point in addition to photospheric perturbations acting as a wave driver mimicking those of p-modes. A variety of MHD waves exist within the vortex tube, including sausage, kink and torsional Alfvén waves, owing to the photospheric wave driver and the nature of the rotational flow itself. By conducting a simulation both with and without the rotational plasma flow, it is shown that the perturbed Poynting flux increases in the presence of the rotational flow as the waves transport increased magnetic energy - attributed to the dynamical pressure from the rotational flow increasing the plasma density at the tube boundary, which acts to trap the wave energy more effectively inside the vortex.

09:30 - 10:30

Discussions: “Challenges in Modeling Vortex Flows”

10:30 - 11:00 Coffee break

11:00 - 11:30

A unified picture of swirl-driven coronal heating: magnetic energy supply and dissipation.

Hidetaka Kuniyoshi (1), Shinsuke Imada (2), Takaaki Yokoyama (3)

1 Northumbria University, UK

2 University of Tokyo, Japan 

3 Kyoto University, Japan

Abstract: The outermost layer of the solar atmosphere is referred to as corona, of which temperature is hundred times hotter than the surface while the ultimate heat source locates at the inner core. The solar coronal heating problem is one of the most critical challenges in solar physics. Recent advancements in observational accuracy have revealed numerous facts that cannot be explained by the conventional classical model of solar coronal heating. Among these, small-scale swirls, whose diameters are comparable to the current instrumental limits, are observed at the top of the convection zone. They have been highlighted as a potential new source of magnetic energy supply to the corona. However, the overall contribution of swirls to the total magnetic energy supply to the corona remains uncertain. Additionally, a theoretical model capable of deriving the magnetic energy dissipation caused by swirls has yet to be established. To address this, we conducted statistical analyses using radiative magnetohydrodynamic simulations that consistently solve the system from the convection zone to the corona. We investigated the statistical properties of magnetic energy supply and dissipation caused by swirls in a unified framework. Our results reveal that swirls account for approximately half of the total magnetic energy supplied to the corona and can trigger magnetic reconnection, achieving magnetic energy dissipation consistent with observed heating signatures.

11:30 - 12:00

Vortex Flows in the Solar Atmosphere: Detection and Heating Mechanisms in 3D MHD Numerical Simulations

Matías Koll Pistarini (1,2), Elena Khomenko (1,2), Tobías Felipe (1,2)

1 Instituto de Astrofísica de Canarias, Spain

2 Departamento de Astrofísica, Universidad de La Laguna, Spain

Abstract: We performed an automatic detection of vortex structures in 3D MHD numerical simulations using the MANCHA3D code. The code incorporates non-ideal MHD effects and simulations are available in three magnetic field configurations at different spatial resolutions. To detect vortices we proposed to use the novel SWIRL code (Canivete Cuissa & Steiner (2022)), which combines mathematical criteria based on the velocity gradient tensor to identify such structures with an advanced clustering algorithm. By applying this code, we have been able to determine multiple structures associated with small-scale vortices that extend in height in our simulations. We focus our study on the temperature distribution and different heating mechanisms that can modify their internal energy such as ambipolar diffusion, and viscous and ohmic dissipation. Attention is also paid on how these quantities change at different magnetic field configuration and spatial resolution. 

12:00 - 13:00

Discussions: “Signatures for plasma heating by vortices”

13:00 - 14:00   Lunch

Afternoon Session - Upper Atmospheric Vortices

13:00 - 13:30

Swirls in stellar coronae

Cosima Breu

University of St Andrews, UK

Abstract: Small-scale vortex motions have been found in abundance in different layers of the solar atmosphere, from the photosphere to the chromosphere with possible signatures in the corona. These structures could play an important role regarding the exchange of mass and energy between different atmospheric layers. While not possible to observe, vortices are also present in MHD simulations of the photospheres of other stars. The properties of vortices have been shown to depend on the magnetic field strength and the stellar type. Using MHD simulations of a straightened out coronal loop, I will investigate whether the different properties of stellar vortices influence the corona.

13:30 - 14:00

Spectral Characteristics of a Rotating Solar Prominence in Multiple Wavelengths

A.G.M. Pietrow (1), V. Liakh (2), C.M.J. Osborne (3), J. Jenkins (2), R. Keppens (2)

1 Leibniz-Institut für Astrophysik Potsdam (AIP), Germany 

2 Centre for Mathematical Plasma Astrophysics, KU Leuven, Belgium 

3 SUPA School of Physics and Astronomy, University of Glasgow, UK

Abstract: The existence of rotational flows in solar prominences, also known as prominence tornadoes, has been a topic of discussion for many decades. Projection effects and a lack of spectral information make it difficult to distinguish rotation from line-of-sight motions, and counter-streaming flow confidently. Recently a 2.5D numerical model was produced using MPI-AMRVAC where rotation flows inside the coronal cavity were initiated and investigated. For the first time, this work showed the properties and evolution of rotational flows in solar prominences, which are in good agreement with existing observations in SDO. In this talk, we continue working on this numerical experiment by extending our analysis to the spectral synthesis of the Hα line, and several other well-used chromospheric lines using the Lightweaver code and its new prominence synthesis method.

14:00 - 15:00

Discussions: “ Detection and analysis of vortices in the upper atmosphere and solar wind”

15:00 - 15:40 Coffee break

15:40 - 16:40

       Discussions: “Future solar missions”

Dinner

04/06/2025- Wednesday

Morning Session - Innovative Techniques in Vortex Flow Analysis

09:00 - 09:30

Multifractal Properties of Magnetic Vortical Flows in Solar Active Region 1158

Leonardo Batista (1), Erico Rempel (2), Breno Raphaldini (3), Suzana SIlva (4), Viktor Fedum (4), Daniel de Freitas (1)

The application of robust analysis techniques is essential for characterizing the physical processes underlying the evolution of magnetic vortices in turbulent active regions. In this study, we apply a multiscale analysis to a stable vortex structure observed in NOAA Active Region 11158 using the Integrated Averaged Current Deviation (IACD) technique. A 169 Mm² subregion containing an M-vortex with a lifetime of 16 hours was selected for the extraction of multifractal parameters via the two-dimensional Multifractal Detrended Moving Average (2D-MFDMA) method. We analyze the temporal evolution of the multifractal spectrum, Rényi exponents, and Hurst exponents, and compare these with parameters describing the vortex boundary. Our results reveal a significant correlation between the intensity of the IACD field and the degree of multifractality in the region. These findings suggest that the presence of coherent vortex structures enhances large-scale fluctuations, thereby increasing the multifractal behavior of the area.

09:40 - 10:30

Discussions: “Beyond Basics: Advanced Methods for Vortex Dynamics Research”

10:30 - 11:00   Coffee break 

11:00 - 13:00

Discussions: “Next steps for SPINS”

13:00 - 14:00   Lunch