About WaLSA

A focused international science team linked to “Waves in the Lower Solar Atmosphere” (WaLSA).

Scientific rationale

Heating of the solar atmosphere (i.e., the chromosphere, transition region, and corona) has been a much-debated topic in solar physics for several decades. Magneto-hydrodynamic (MHD) waves are often presented as a principal mechanism allowing the transfer of energy and momentum between the solar interior and these elevated layers.

Current generation solar telescopes, including the Swedish 1-m Solar Telescope (SST) and the Dunn Solar Telescope (DST), are pro- ducing a plethora of high-quality imaging and spectro-polarimetric datasets. Importantly, the multi-wavelength optical and infrared ob- servations produced contain a wealth of information related to MHD wave processes created within the Sun’s dynamic lower atmosphere. These oscillations, in the form of slow/fast magneto-acoustic and Alfvén waves, have the potential to transfer vast quantities of energy flux into the solar chromosphere and corona, where the immense radiative losses need to be balanced. Furthermore, the differing energy and plasma transmission rates as one moves through the various layers of the solar atmosphere naturally provides implications when relating the Sun’s energetics to those encountered in the heliosphere.

Recent investigations have focussed on the detection and iden- tification of mixed-property wave modes existing across different magnetic solar features (e.g., sunspots, pores, magnetic bright points, spicules, filaments, etc.). In order to make the quantification of wave properties as accurate as possible, theoretical aspects of spectro-polarimetry, partial ionisation and radiative transfer pro- cesses need to be incorporated, especially since the lower solar atmosphere is governed by optically thick plasma conditions. Many recent ground-breaking publications have begun to include Stokes inversion processes in order to better understand the spectropo- larimetric signatures resulting from the passage of energetic wave fronts through the highly stratified solar atmosphere. However, these types of processes are not without significant challenges. Often, the captured spectro-polarimetric Stokes profiles are significantly asymmetric and evolve on timescales shorter than typical camera integration times.

It is therefore imperative to bring together leading experts in observations, instrument design, wave theory, numerical simulations, spectro-polarimetric inversions and radiative transfer processes in order to drive forward cutting-edge research that will benefit the global astrophysical community for decades to come. WaLSA is an international science team that concentrates research efforts in order to yield reliable estimates of the energy transported by MHD waves into the upper solar atmosphere, and provide new insight into the dissipation mechanisms of these waves and, hence, their contribution to heating the outer layers of the solar atmosphere.

It is worth highlighting that the timeliness for such a meeting is of vital importance, due to the upcoming Daniel K. Inouye Solar Telescope (DKIST) and European Solar Telescope (EST) facilities, which will revolutionise our vantage points of oscillatory phenomena in the Sun’s atmosphere. It is expected that the in-depth discus- sions and subsequent focussed research efforts will have significant implications for upcoming DKIST, EST, and ALMA observations.

WaLSA organisation

In addition to the core members, the science objectives are being fulfilled in collaboration and involvement of other scientists in the field. In particular, a number of associate members, who also play a leading role in WaLSA’s science projects, are being added to the team. Students (in both master and PhD levels) are also being involved in the research. Graduate students and scientists with an interest in the WaLSA-related activities may join the team as affiliate members. 

The WaLSA Team meets online on regular basis, but also with a minimum of one face-to-face meeting per year to discuss recent research results, identify challenges related to the team’s scientific objectives, and aid the coordination of team's projects, to name but a few. The kickoff meeting of the WaLSA team took place at the University of Oslo, Norway, during 7-11 January 2019. The team is aiming at continuation of such meetings over the coming years. 

The WaLSA Team is open to collaborations with other researchers in the field. Additionally, the team offers supervisions at both undergraduate and graduate levels related to the team’s science activities. Helps to apply for studentships are happily provided. Contacts from researchers and students interested in the team’s activities, as well as from media, schools, and the public relation sectors are mostly welcome.

Team members

The WaLSA Team consists of 12 core members from 7 countries, as well as a couple of associate and affiliate members. The team members hold a wealth of experience in the handling, preparation, and exploitation of high-resolution data sequences from modern ground-based and space-borne solar observatories, as well as in theory and simulations, spectro-polarimetric signatures, and radiative transfer processes.

Core members:

Shahin Jafarzadeh 

Researcher (Team coordinator) 

Rosseland Center for Solar Physics, University of Oslo.


Associate members: 

Vasco Manuel de Jorge Henriques 

Postdoctoral Fellow

Rosseland Center for Solar Physics, University of Oslo.


For a complete list of the WaLSA team members, visit the WaLSA website.

Published July 19, 2019 4:38 PM - Last modified Mar. 30, 2020 5:52 PM