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High resolution wave dynamics in the lower solar atmosphere
Theo Murphy international scientific meeting organised by Dr David Jess, Dr Peter Keys, Dr Marco Stangalini and Dr Shahin Jafarzadeh.
You can find out more this research team, their research and other activities at WaLSA (Waves in the Lower Solar Atmosphere).
A focused meeting to discuss the current challenges faced in wave studies in the lower solar atmosphere, including those related to spectropolarimetry and radiative transfer in the optically thick atmosphere. Implications imposed on upcoming next-generation ground-based facilities such as DKIST and EST, alongside space and balloon-borne missions like Solar Orbiter and SUNRISE, will also be discussed.
Speaker abstracts are available below. Recorded audio of the presentations are also below.
Attending this event
This meeting has taken place.
Enquiries: contact the Scientific Programmes team.
Organisers
Schedule
| 09:20 - 09:40 |
Local helioseismology of solar surface activity
Active regions consist of strong magnetic fields on the surface of the Sun, and are the principal signature of the solar dynamo. Knowing the subsurface structure of active regions will help us understand where in the solar interior the solar dynamo is located. Dr Schunker's earlier research demonstrated that interpreting the results from helioseismology, the only tool that can probe the subsurface structure of the Sun, is difficult because the waves have been strongly perturbed by the presence of strong surface magnetic fields. In sunspots, the group believes the largest perturbations are caused by the structure of the sunspot itself and by the waves undergoing mode conversion. Different wave perturbations are observed in the surrounding plage regions, and the mechanism causing these wave perturbations is more poorly constrained. To make progress we need higher spatial resolution observations to resolve the vector magnetic field structure, and numerical simulations to understand the physical cause of the wave perturbations. Understanding the physics of wave propagation in the different regions of strong surface magnetic field will help us to constrain the transfer of energy via waves from the interior to the corona, interpret the helioseismic signature to correctly infer the subsurface structure, and could potentially be used to infer surface activity on distant Sun-like stars. 
Dr Hannah Schunker, Max Planck Institute for Solar System Research, Germany
Dr Hannah Schunker, Max Planck Institute for Solar System Research, GermanyDr Schunker's scientific goal is to understand the solar dynamo. She undertook her doctoral studies in astrophysics at Monash University, Australia under the supervision of Professor Paul Cally, studying the effect of sunspots on solar oscillations. Since 2006 she has been employed at the Max Planck Institute for Solar System Research as a post-doctoral researcher, project scientist, and now staff scientist in the department of Solar and Stellar Interiors. Dr Schunker's research has two main focuses |
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| 09:40 - 10:00 | Discussion | |
| 10:00 - 10:20 |
The generation and evolution of swirls in the solar atmosphere
Vortical motions of plasma are of ubiquitous presence in photospheric and chromospheric layers of the solar atmosphere. Swirls of small scale in the chromosphere have been observed to occur co-spatially with magnetic flux concentrations of the deep photosphere, suggesting the magnetic origin of these swirls. One scenario suggests magnetic flux concentrations that root in swirling downdrafts of intergranular lanes to rotate, thereby dragging chromospheric material with them, causing the chromospheric swirls. Another scenario sees the chromospheric swirls to be a manifestation of torsional Alfvén waves, either locally generated in the chromosphere or propagating from the photosphere into the chromoshere. Looking at numerical simulations and a quantity called swirling strength, the group finds events of unidirectional torsional motion propagating with Alfvén speed from the photospheric footpoints of magnetic flux concentrations in the upward direction. Oskar Steiner concludes that such propagating, unidirectional swirls can be best interpreted in terms of a propagating torsional Alfvén-wave package that seems to arise from the deformation and strengthening of a preexisting flux concentration rather than a proper rotation of it. 
Oskar Steiner, Leibniz Institute for Solar Physics (KIS) and Istituto Ricerche Solari Locarno (IRSOL), Germany and Switzerland
Oskar Steiner, Leibniz Institute for Solar Physics (KIS) and Istituto Ricerche Solari Locarno (IRSOL), Germany and SwitzerlandOskar Steiner is a senior researcher at the Leibniz Institute for Solar Physics KIS in Freiburg, Germany, and at the Istituto Ricerche Solari Locarno (IRSOL) in Locarno, Switzerland. His main research interests focus on the numerical simulation of the small scale magnetism of the Sun and stellar atmospheres and on the transfer of polarized radiation and corresponding numerical methods. He carried out numerical experiments of wave propagation and conversion for the interpretation and prediction of observable signals of wave activities in the solar atmosphere. More recently, he is interested in different kinds of vortical motions in the solar atmosphere, in particular there origin and impact. |
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| 10:20 - 10:40 | Discussion | |
| 10:40 - 11:10 | Coffee break | |
| 11:10 - 11:30 |
Waves in the Lower Solar Atmosphere: examining small-scale magnetic elements as a source of waves
Highly dynamic small-scale features such as magnetic bright points (MBPs) are ubiquitous across the solar surface. They present an excellent opportunity to study waves in the lower solar atmosphere. Due to their ubiquity, it is essential that their contributions to energy transfer between layers is ascertained. Dr Keys will discuss how recent work highlights the complexities involved in establishing the wave properties of these dynamic features during their evolution. Dr Keys will then outline the steps that are currently underway to utilise both high resolution imaging and MHD simulations to address these issues in order to better understand wave propagation within MBPs. 
Dr Peter Keys, Queen’s University Belfast, UK
Dr Peter Keys, Queen’s University Belfast, UKPeter Keys is a solar physicist whose work focuses on the lower solar atmosphere of the Sun using ground-based observations. His work centres on the dynamics of small-scale magnetic elements that are ubiquitous across the solar disc. His work on these elements follows their evolution and formation, as well as waves that are found to propagate along them. Peter was an instrument scientist for several years for the Rapid Oscillations in the Solar Atmosphere instrument at the Dunn Solar Telescope, and more recently was a Leverhulme Trust Early Career Fellow looking at waves in small-scale magnetic elements. |
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| 11:30 - 11:50 | Discussion | |
| 11:50 - 12:10 |
HMI observations of MHD waves in the lower solar atmosphere
The conversion of p-modes and other perturbations in the near-surface layers into MHD waves that propagate along and across magnetic field lines is a topic of interest for energy transport. The photospheric signatures of MHD waves are weak due to low amplitudes at the β=1 equipartion level where mode-conversion occurs. Dr Norton will briefly discuss HMI helioseismic studies that shed light on MHD wave generation in the vicinity of strong magnetic fields. She will then discuss observed oscillations and other signatures in time series analysis of HMI data. Lastly, Dr Norton will emphasis how HMI supports instruments with higher spatial and temporal resolution for the study of wave dynamics. 
Dr Aimee Norton, Stanford University, USA
Dr Aimee Norton, Stanford University, USAAimee A Norton is an astronomer who works at Stanford University researching the Sun’s magnetic fields. As a member of the Helioseismic and Magnetic Imager (HMI) instrument team, her interests are observational and include both the short and long time scales of solar magnetism, ie, MHD waves and the solar dynamo. As a hobby, she writes poetry and enjoys the parallel ways in which physics and poetry compress big, experiential truths into small spaces. She obtained a PhD in Physics and Astronomy from the University of California Los Angeles. She serves as a science editor for the Astrophysical Journal. |
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| 12:10 - 12:30 | Discussion |
Chair
Dr Marco Stangalini, ASI, Italian Space Agency, Italy
Dr Marco Stangalini, ASI, Italian Space Agency, Italy
Marco Stangalini is a researcher at ASI (Italian Space Agency), and his main research focuses on the plasma and magnetic field dynamics in the lower solar atmosphere. In particular, his interests are primarily the study of MHD waves, through the analysis of high spatial resolution spectropolarimetric data, and the development of new high resolution instrumentation.
| 13:30 - 13:50 |
Multi-fluid effects on chromospheric waves
Dr Elena Khomenko, Instituto de Astrofisica de Canarias, Spain
Dr Elena Khomenko, Instituto de Astrofisica de Canarias, SpainElena Khomenko received a PhD in Physics and Math from Main Astronomical Observatory in Kiev (Ukraine) in 2004 and is a Research scientist at the Instituto de Astrofisica de Canarias (IAC, Spain). Elena has been mostly working in the field of Solar Physics, MHD wave theory, theory of partially ionized plasmas, quiet Sun magnetic fields, and spectropolarimetry. One of Elena’s research lines is the study of the interaction of solar waves and magnetic structures. The main milestone of this line is the creation of a numerical code Mancha3D, a non-linear code that solves equations of non-ideal MHD in three spatial dimensions including realistic ingredients. Her current interests focus on the investigation of the influence of partial ionization of the solar plasma onto the processes of energy propagation and release, for which she got funding from the European Research Council throughout the Starting Grant in 2011 and Consolidating Grant in 2017. |
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| 13:50 - 14:10 | Discussion | |
| 14:10 - 14:30 |
Wave coupling and heating of expanding flux tubes in the chromosphere
Waves travelling though the chromosphere propagate through the beta=1 surface in expanding flux tubes and may also be reflected by the temperature jump in the transition region. Determining which modes are responsible for energy transmission from photosphere to corona is essential as it determines which heating mechanisms are most likely to be effective. This talk briefly summarises recent simulations on the chromospheric resonant cavity, Alfven wave to slow wave coupling and the possibility of upper chromospheric heating from shocks. 
Professor Tony Arber, University of Warwick, UK
Professor Tony Arber, University of Warwick, UK
Professor Arber completed a PhD and several research positions in fusion research at Imperial College, London before joining the St Andrews Solar group in 1996. Since 2000 he has been at the University of Warwick where his research interests are in computational plasma physics applied to solar physics, space weather, laser-plasma interactions, fusion and QED-plasmas.
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| 14:30 - 14:50 | Discussion | |
| 14:50 - 15:20 | Coffee break | |
| 15:20 - 15:40 |
Acoustic-gravity wave propagation characteristics in 3D radiation hydrodynamic simulations of the solar atmosphere
There has been tremendous progress in developing 'realistic' 3D radiation hydrodynamic simulations of the solar atmosphere in the past decade. Four of the most frequently used numerical codes are Bifrost (Gudiksen et al 2011, Carlsson et al 2016), CO5BOLD (Freytag et al 2012), MANCHA3D (Khomenko et al 2018), and MURaM (Vögler et al 2005, Rempel 2014). Some of these models were benchmarked for their average properties in the near-surface layers, by comparing their average stratifications as well as their temporal and spatial fluctuations (eg RMS of granular contrast and vertical velocities; Beeck et al 2012). Here Dr Fleck tests and compares the wave propagation characteristics of these four models by measuring the dispersion relation of acoustic-gravity waves at various heights. The group finds considerable differences between the various model runs. 
Dr Bernhard Fleck, European Space Agency (ESA)
Dr Bernhard Fleck, European Space Agency (ESA)Bernhard Fleck received his PhD in physics in 1991 from the University of Würzburg, Germany. In 1993 he joined the European Space Agency to work on the SOHO project. In 1998 he became the ESA Project Scientist for SOHO and later also the ESA Project Scientist for Hinode and IRIS. He has been based at NASA Goddard Space Flight Center near Washington, DC, USA, since 1995. His research interests include the dynamics and energetics of the solar atmosphere, in particular the wave-propagation characteristics of gravity waves and high-frequency acoustic waves in the photosphere and chromosphere. |
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| 15:40 - 16:00 | Discussion | |
| 16:00 - 16:20 |
Oscillations observed with ALMA
Dr Jafarzadeh reports characterisations of temperature fluctuations observed with the Atacama Large Millimeter/submillimeter Array (ALMA) and highlights how they can improve our knowledge on, eg, heating dissipation in the solar chromosphere. In particular, he discusses the observed frequencies in comparison with those obtained from oscillations in temperature, line-of-sight velocity, and gas density from the Bifrost numerical simulations. In addition, Dr Jafarzadeh presents direct observations of excess temperature (by larger than 1000 K) in a small quiet-Sun region. Such excess temperature/brightness is not observed in the upper layers of the solar atmosphere (ie, the transition region), suggesting energy release at the chromospheric heights. 
Dr Shahin Jafarzadeh, University of Oslo, Norway
Dr Shahin Jafarzadeh, University of Oslo, NorwayShahin Jafarzadeh is a researcher at Rosseland Centre for Solar Physics (RoCS), University of Oslo, Norway. His main studies concern the lower-to-mid atmosphere of the Sun, regarding how magnetic fields structure dynamics of those layers — towards understanding the mysterious heating of the Sun's atmosphere. He is predominantly interested in characterisation of wave activity in the lower solar atmosphere. To this end, he works within the WaLSA international science team (https://WaLSA.team), of which, he is a coordinator. Shahin is an experienced observer and passionately engages in public outreach activities. In particular, he has been part of various science teams associated with the SUNRISE 1-m balloon-borne solar observatory, with the Swedish 1-m Solar Telescope (SST) and, more recently, with ALMA. |
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| 16:20 - 17:00 | Discussion | |
| 17:00 - 18:00 | Poster session |
Chair
Dr Shahin Jafarzadeh, University of Oslo, Norway
Dr Shahin Jafarzadeh, University of Oslo, Norway
Shahin Jafarzadeh is a researcher at Rosseland Centre for Solar Physics (RoCS), University of Oslo, Norway. His main studies concern the lower-to-mid atmosphere of the Sun, regarding how magnetic fields structure dynamics of those layers — towards understanding the mysterious heating of the Sun's atmosphere. He is predominantly interested in characterisation of wave activity in the lower solar atmosphere. To this end, he works within the WaLSA international science team (https://WaLSA.team), of which, he is a coordinator. Shahin is an experienced observer and passionately engages in public outreach activities. In particular, he has been part of various science teams associated with the SUNRISE 1-m balloon-borne solar observatory, with the Swedish 1-m Solar Telescope (SST) and, more recently, with ALMA.
| 09:20 - 09:40 |
Properties of local oscillations in lower sunspot atmospheres
Dr Sych will present a study of wave processes in the sunspot region observed by the Goode Solar Telescope in the TiO 7057 Å and Hα 6563 Å spectral lines. To study the distribution of power oscillations and their dynamics, the pixelized wavelet filtering technique was applied. For the first time, the group obtained the spatial structure of oscillation sources as the footpoints of fine magnetic tubes, anchored in the sunspot umbra. At the chromosphere level, the variation of emission is a combination of numerous independent oscillations located in the sources with small angular size. Their spatial shape varies from dots and cells in the umbra to filaments in the penumbra. Each narrow spectral harmonic corresponds to its source, without global correlation among themselves. At the photosphere level the group found regions with co-phased broadband oscillations of the whole umbra. Their spectrum includes the ∼3 minutes harmonic, whose maximal value is localized in umbral dots. The oscillation sources are displaced at different heights with increasing angular size. Dr Sych assumes that the observed spatial distribution of wave sources indicates the existence of a slow subphotospheric resonator with a vertical magnetic field in the umbra and a wave cutoff frequency due to inclination of the magnetic field line in the penumbra. 
Dr Robert Sych, Institute of Solar-Terrestrial Physics, Russia
Dr Robert Sych, Institute of Solar-Terrestrial Physics, RussiaDr Robert Sych is a Leading researcher at the Radioastrophysical Division of the Institute of Solar-Terrestrial Physics, Irkutsk, Russia. His main scientific interests joint with solar physics are radioastrophysics, helioseismology, sunspot oscillations and data processing techniques. Robert is the main developer of the Pixelized Wavelet Filtering digital technique (PWF-analysis), which is used for detection wave and oscillations in solar imaging data cube. His current interests concentrate on developing the connectivity model of the solar lower atmosphere and corona by MHD waves, improving the model of 3-minute oscillations in sunspots atmosphere and studying the relationships between wave dynamics and umbral fine energy phenomena, like umbral flashes and dots. At present he is a SCOSTEP Scientific Discipline Representative from Russia on Solar physics. |
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| 09:40 - 10:00 | Discussion | |
| 10:00 - 10:20 |
Comprehensive MHD simulations of the solar atmosphere from quiet to active Sun
Coupling the photosphere and corona requires bridging a large separation of length- and time-scales. While typical photospheric time-scales of interest range from minutes (granulation) to days (active region flux emergence), numerical time-step constraints in the corona can be very severe due to Alfven velocities exceeding 100,000 km/s and very efficient heat conduction. Dr Rempel presents a recently developed version of the MURaM (Max Planck University of Chicago Radiative MHD) code that includes coronal physics in terms of optically thin radiative losses and field aligned heat conduction. The code employs the "Boris correction" (semi-relativistic MHD with a reduced speed of light) and a hyperbolic treatment of heat conduction, which allow for efficient simulations of the photosphere/corona system by avoiding the severe time-step constraints arising from Alfven wave propagation and heat conduction. He discusses applications of the code that include studies of quiet sun magnetism, flux emergence and active region formation, and a simulation of a solar flare in response to active region scale flux emergence. 
Dr Matthias Rempel, High Altitude Observatory, National Center for Atmospheric Research, USA
Dr Matthias Rempel, High Altitude Observatory, National Center for Atmospheric Research, USAMatthias Rempel received his diploma in physics in 1998 and his PhD in astrophysics in 2001 from the University of Goettingen, Germany. Since 2002 Matthias Rempel has been working at the High Altitude Observatory (HAO) of the National Center for Atmospheric Research (NCAR) in Boulder, Colorado. From 2002 to 2004 he received an ASP postdoctoral fellowship and since 2004 he has been a staff scientist at HAO. Dr Rempel has over 15 years of experience in solar physics research efforts, in particular he is a leader in numerical modelling of the solar atmosphere through radiation MHD simulations. He is one of the key developers of the MURaM radiative MHD code and has led groundbreaking investigations of quiet sun magnetism, sunspot structure, flux emergence and comprehensive simulations of solar flares. |
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| 10:20 - 10:40 | Discussion | |
| 10:40 - 11:10 | Coffee break | |
| 11:10 - 11:30 |
The modelling and interpretation of magnetohydrodynamic wave modes in sunspots and pores
In this talk Dr Verth will present some interesting case studies where current theoretical understanding explains reasonably well the MHD oscillations observed in eg, the umbral regions of sunspots. In these cases he will explain what the theory predicts in terms of intensity, Doppler velocity and LOS magnetic field oscillations with regards to magnetic waveguides of both circular and elliptical cross-sectional shape. Dr Verth will then go on to describe what MHD models need to be developed to interpret oscillations detected in eg, pores of more irregular cross-sectional shape. 
Dr Gary Verth, University of Sheffield, UK
Dr Gary Verth, University of Sheffield, UKGary Verth studied at the University of Glasgow (MSci 2004), University of Sheffield (PhD 2008), Katholieke Universiteit Leuven and Northumbria University (Postdoctoral Research Fellow 2008–2012). He was awarded the Leverhulme Early Career Fellowship (2012–2015) and took up a lectureship in applied mathematics at the University of Sheffield in 2015. He specialises in both the theory and observational interpretation of magnetohydrodynamic waves in the solar atmosphere, in both large-scale (eg, sunspots and pores) and small-scale (eg, spicules and chromospheric fibrils) magnetic structures. He has taken leading roles in various specialist solar waves workshops at eg, the International Space Science Institute (Bern) and the Rosseland Centre for Solar Physics (Oslo). He has also been invited to contribute numerous review articles on solar wave physics for eg, Space Science Reviews and American Geophysical Union Monographs.
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| 11:30 - 11:50 | Discussion | |
| 11:50 - 12:10 |
Can p-modes play a role in powering the corona?
Alfvénic waves are thought to play a crucial role in the heating of the Sun’s atmosphere and acceleration of the solar wind, and it is now established that they are present throughout the corona. However, there are crucial questions remaining about the journey of the waves through the lower solar atmosphere. Recent results suggest that p-modes may make an unexpected contribution to the coronal energy flux. In this talk Dr Morton will summarise what we already know about Alfvenic waves in the chromosphere and corona. He will also focus on the recent observations of the low corona (<1.3 R_sun), mainly from ground-based observations with the Coronal Multi-channel Polarimeter (CoMP), and what they reveal about the waves journey. Finally he will discuss the implications for wave heating and wind acceleration if p-modes do play an important role and avenues for probing this new pathway for energy transfer. 
Dr Richard Morton, Northumbria University, UK
Dr Richard Morton, Northumbria University, UKDr Morton is a Senior Lecturer at Northumbria University, having recently finished a prestigious Leverhulme Trust Early Career Research Fellowship. He currently leads a small research group who are motivated to understand the role magnetohydrodynamic waves play in transferring energy around the Sun’s atmosphere, powering the heating of the million-degree solar wind and its acceleration to a million miles per hour. Dr Morton has a track record of utilising remote observations of the Sun to probe them, developing unique and innovative data analysis methodology to make significant contributions to our knowledge of the fundamental properties of these waves and details of their propagation. |
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| 12:10 - 12:30 | Discussion |
Chair
Dr Elena Khomenko, Instituto de Astrofisica de Canarias, Spain
Dr Elena Khomenko, Instituto de Astrofisica de Canarias, Spain
Elena Khomenko received a PhD in Physics and Math from Main Astronomical Observatory in Kiev (Ukraine) in 2004 and is a Research scientist at the Instituto de Astrofisica de Canarias (IAC, Spain). Elena has been mostly working in the field of Solar Physics, MHD wave theory, theory of partially ionized plasmas, quiet Sun magnetic fields, and spectropolarimetry. One of Elena’s research lines is the study of the interaction of solar waves and magnetic structures. The main milestone of this line is the creation of a numerical code Mancha3D, a non-linear code that solves equations of non-ideal MHD in three spatial dimensions including realistic ingredients. Her current interests focus on the investigation of the influence of partial ionization of the solar plasma onto the processes of energy propagation and release, for which she got funding from the European Research Council throughout the Starting Grant in 2011 and Consolidating Grant in 2017.
| 13:30 - 13:50 |
The polarization profiles of Ca II 854.2 nm in a Quiet Sun simulation
Ca II 854.2 nm has been deemed one of the most promising spectral line diagnostics for the chromospheric magnetic field, due to its accessibility from ground-based observations and the relative ease of its interpretation. The standard tools used for the interpretation of this spectral line do not account for the physics of scattering polarization nor its modification due to the Hanle effect. However, scattering polarization signatures typically dominate the linear polarization profiles of Ca. II 854.2 nm in weak field areas (Manso Sainz & Trujillo Bueno 2010, 2003), particularly close to the limb. When combined with the enhancing effect of shocks, these linear polarization signals can reach amplitudes of up to 1% of the continuum intensity (Carlin et al 2012), which would drown Zeeman-polarization signatures induced by magnetic fields in the low hecto-gauss range. In this work Rebecca Centeno evaluates the temporal evolution of the polarization profiles of Ca II 854.2 nm that emerge from a Quiet Sun simulation from MuRAM. The effects of the magnetic field and the line-of-sight velocity are analyzed separately in order to quantify their individual contributions to the linear polarization. 
Rebeca Centeno, High Altitude Observatory (NCAR), USA
Rebeca Centeno, High Altitude Observatory (NCAR), USARebeca Centeno is a Project Scientist at the High Altitude Observatory of the National Center for Atmospheric Research, in Colorado (USA). Her main scientific interest lies in the field of Solar Spectropolarimetry for remote sensing of magnetic fields on the Sun. Magnetic fields play a fundamental role in the structure, the dynamics and the energy budget of the Sun's atmosphere, and they constitute the main drivers of Space Climate and Space Weather. The polarized spectrum of the Sun carries a wealth of information about the physical properties of its atmosphere. By combining spectropolarimetric observations with theoretical knowledge of radiative transfer, we can decipher this information and thus quantify the vector magnetic field and thermodynamical properties as a function of location and time. |
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| 13:50 - 12:10 | Discussion | |
| 14:10 - 14:30 |
Waves captured by spectropolarimetric IBIS obversations
Spectropolarimetry has become a mature tool for the analysis of the dynamics of the lower solar atmosphere. Next generation solar instrumentation, characterized by unmatched polarimetric accuracy and sensitivity, will dramatically improve our observational capabilities, extending the use of spectropolarimetric diagnostics down to very small spatial scales (< 100 km) and higher atmospheric heights. In this contribution Dr Stangalini will show how simultaneous spectropolarimetric observations at multiple heights is a powerful tool to reveal the details about the plasma and magnetic field wave dynamics in the solar atmosphere, and for the identification of Alfvénic disturbances. More in detail, he will show the capabilities of tomographic spectropolarimetric imaging in the investigation of MHD waves, by presenting recent results from high resolution state-of-the-art observations of the solar atmosphere and, in particular, from IBIS.
Dr Marco Stangalini, ASI, Italian Space Agency, Italy
Dr Marco Stangalini, ASI, Italian Space Agency, ItalyMarco Stangalini is a researcher at ASI (Italian Space Agency), and his main research focuses on the plasma and magnetic field dynamics in the lower solar atmosphere. In particular, his interests are primarily the study of MHD waves, through the analysis of high spatial resolution spectropolarimetric data, and the development of new high resolution instrumentation. |
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| 14:30 - 14:50 | Discussion | |
| 14:50 - 15:20 | Coffee break | |
| 15:20 - 15:40 |
Two-fluid shocks in an isothermal stratified atmosphere
A compressional wave propagating upwards in the solar atmosphere naturally steepens due to the stratification of the atmosphere and can readily develop nonlinearities and shock. If the magnetic field is inclined, a shock can separate into fast- and slow- mode components as it passes through the point where the sound and Alfven speed are equal. This point can occur in the lower solar atmosphere, where the plasma is partially-ionised and two-fluid effects become important. In this talk, Dr Snow will present results from two-fluid numerical simulations demonstrating the mode conversion and interplay between the ionised and neutral species for a shock wave propagating through an isothermal stratified atmosphere. 
Dr Ben Snow, University of Exeter, Uk
Dr Ben Snow, University of Exeter, UkBen Snow is a postdoc at the University of Exeter studying the effects of partially ionised plasma. In particular, his research activities include performing two-fluid numerical simulations of shocks and the interactions between neutral and ionised species. He also have projects investigating the behaviour of resonances above sunspot umbrae, and constructing 3D non-force-free magnetic atmospheres from observed magnetograms. Previously, he was a PDRA at the University of Sheffield, investigating wave interactions in interacting pairs of magnetic flux tubes. Dr Snow's PhD was entitled 'Numerical Simulations of Chromospheric Physics' and was attained at Northumbria University, where he researched chromospheric resonance, magnetic reconnection, and forward modelling. |
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| 15:40 - 16:00 | Discussion | |
| 16:00 - 16:20 |
Waves in the lower solar atmosphere: setting the scene for the next generation of solar telescopes
The development of cutting-edge three-dimensional simulations has highlighted a vast assortment of predicted solar phenomena that reside below the spatial, temporal, and spectral resolutions of current telescope facilities. Thankfully, next-generation solar telescopes (including DKIST, SUNRISE, NLST, EST, and Solar-C) will improve the spatial resolutions achievable. However, it is the role of the instruments commissioned on these revolutionary facilities that will pave the way for robust comparisons to be made to the cutting-edge numerical simulations pioneered by the likes of Mancha, Bifrost, MuRAM, and LareXd. Here, Dr Jess will present overarching requirements of such new-age instrumentation, including a description of a hyper-spectropolarimetric imager currently under construction for the Indian National Large Solar Telescope. Lastly, Dr Jess will highlight the scientific challenges discussed during the Royal Society’s High Resolution Wave Dynamics in the Lower Solar Atmosphere Theo Murphy meeting, and suggest ways how combined novel instrumentation, alongside collaborative efforts within the solar physics community, will provide rapid developments in the understanding of wave phenomena in the lower solar atmosphere. 
Dr David Jess, Queen's University Belfast, UK
Dr David Jess, Queen's University Belfast, UKDavid Jess is a solar physicist whose work predominantly explores the lower atmosphere of the Sun, with an emphasis placed on understanding energy flow through the turbulent and dynamic layers of the photosphere and chromosphere in the form of magnetohydrodynamic waves. He has held independent Research Fellowships from STFC and the EU, and is the Principal Investigator of the Hydrogen-Alpha Rapid Dynamics camera (HARDcam) instrument at the Dunn Solar Telescope, USA, and is currently building a fibre-fed, near-UV hyper-spectropolarimetric imager for the Indian National Large Solar Telescope. He was appointed to his current role as academic staff at Queen’s University Belfast in 2013. |
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| 16:20 - 17:00 | Meeting overview and future directions (discussion) |