MIST

Magnetosphere, Ionosphere and Solar-Terrestrial

Latest news

Announcement of New MIST Councillors.

We are very pleased to announce the following members of the community have been elected unopposed to MIST Council:

  • Rosie Johnson (Aberystwyth University), MIST Councillor
  • Matthew Brown (University of Birmingham), MIST Councillor
  • Chiara Lazzeri (MSSL, UCL), Student Representative

Rosie, Matthew, and Chiara will begin their terms in July. This will coincide with Jasmine Kaur Sandhu, Beatriz Sanchez-Cano, and Sophie Maguire outgoing as Councillors.

The current composition of Council can be found on our website, and this will be amended in July to reflect this announcement (https://www.mist.ac.uk/community/mist-council).

Nominations are open for MIST Council

We are very pleased to open nominations for MIST Council. There are three positions available (detailed below), and elected candidates would join Georgios Nicolaou, Andy Smith, Maria-Theresia Walach, and Emma Woodfield on Council. The nomination deadline is Friday 31 May.

Council positions open for nomination

2 x MIST Councillor - a three year term (2024 - 2027). Everyone is eligible.

MIST Student Representative - a one year term (2024 - 2025). Only PhD students are eligible. See below for further details.

About being on MIST Council

If you would like to find out more about being on Council and what it can involve, please feel free to email any of us (email contacts below) with any of your informal enquiries! You can also find out more about MIST activities at mist.ac.uk. Two of our outgoing councillors, Beatriz and Sophie, have summarised their experiences being on MIST Council below.

Beatriz Sanchez-Cano (MIST Councillor):

"Being part of the MIST council for the last 3 years has been a great experience personally and professionally, in which I had the opportunity to know better our community and gain a larger perspective of the matters that are important for the MIST science progress in the UK. During this time, I’ve participated in a number of activities and discussions, such as organising the monthly MIST seminars, Autumn MIST meetings, writing A&G articles, and more importantly, being there to support and advise our colleagues in cases of need together with the wonderful council members. MIST is a vibrant and growing community, and the council is a faithful reflection of it."

Sophie Maguire (MIST Student Representative):

"Being the student representative for MIST council has been an amazing experience. I have been part of organizing conferences, chairing sessions, and writing grant applications based on the feedback MIST has received. From a wider perspective, MIST has helped to grow and support my professional networks which in turn, directly benefits my PhD work as well. I would encourage any PhD student to apply for the role of MIST Student Representative and I would be happy to answer any questions or queries you have about the role."

How to nominate

If you would like to stand for election or you are nominating someone else (with their agreement!) please email This email address is being protected from spambots. You need JavaScript enabled to view it. by Friday 31 May. If there is a surplus of nominations for a role, then an online vote will be carried out with the community. Please include the following details in the nomination:

  1. Name
  2. Position (Councillor/Student Rep.)
  3. Nomination Statement (150 words max including a bit about the nominee and focusing on your reasons for nominating. This will be circulated to the community in the event of a vote.)

MIST Council details

  • Sophie Maguire, University of Birmingham, Earth's ionosphere - This email address is being protected from spambots. You need JavaScript enabled to view it. 
  • Georgios Nicolaou, MSSL, solar wind plasma - This email address is being protected from spambots. You need JavaScript enabled to view it. 
  • Beatriz Sanchez-Cano, University of Leicester, Mars plasma - This email address is being protected from spambots. You need JavaScript enabled to view it.
  • Jasmine Kaur Sandhu, University of Leicester, Earth’s inner magnetosphere - This email address is being protected from spambots. You need JavaScript enabled to view it.
  • Andy Smith, Northumbria University, Space Weather - This email address is being protected from spambots. You need JavaScript enabled to view it. 
  • Maria-Theresia Walach, Lancaster University, Earth’s ionosphere - This email address is being protected from spambots. You need JavaScript enabled to view it. 
  • Emma Woodfield, British Antarctic Survey, radiation belts - This email address is being protected from spambots. You need JavaScript enabled to view it. 
  • MIST Council email - This email address is being protected from spambots. You need JavaScript enabled to view it. 

Winners of Rishbeth Prizes 2023

We are pleased to announce that following Spring MIST 2023 the Rishbeth Prizes this year are awarded to Sophie Maguire (University of Birmingham) and Rachel Black (University of Exeter).

Sophie wins the prize for the best MIST student talk which was entitled “Large-scale plasma structures and scintillation in the high-latitude ionosphere”. Rachel wins the best MIST poster prize, for a poster entitled “Investigating different methods of chorus wave identification within the radiation belts”. Congratulations to both Sophie and Rachel!

As prize winners, Sophie and Rachel will be invited to write articles for Astronomy & Geophysics, which we look forward to reading.

MIST Council extends their thanks to the University of Birmingham for hosting the Spring MIST meeting 2023, and to the Royal Astronomical Society for their generous and continued support of the Rishbeth Prizes.

Nominations for MIST Council

We are pleased to open nominations for MIST Council. There are two positions available (detailed below), and elected candidates would join Beatriz Sanchez-Cano, Jasmine Kaur Sandhu, Andy Smith, Maria-Theresia Walach, and Emma Woodfield on Council. The nomination deadline is Friday 26 May.

Council positions open for nomination

  • MIST Councillor - a three year term (2023 - 2026). Everyone is eligible.
  • MIST Student Representative - a one year term (2023 - 2024). Only PhD students are eligible. See below for further details.

About being on MIST Council


If you would like to find out more about being on Council and what it can involve, please feel free to email any of us (email contacts below) with any of your informal enquiries! You can also find out more about MIST activities at mist.ac.uk.

Rosie Hodnett (current MIST Student Representative) has summarised their experience on MIST Council below:
"I have really enjoyed being the PhD representative on the MIST council and would like to encourage other PhD students to nominate themselves for the position. Some of the activities that I have been involved in include leading the organisation of Autumn MIST, leading the online seminar series and I have had the opportunity to chair sessions at conferences. These are examples of what you could expect to take part in whilst being on MIST council, but the council will welcome any other ideas you have. If anyone has any questions, please email me at This email address is being protected from spambots. You need JavaScript enabled to view it..”

How to nominate

If you would like to stand for election or you are nominating someone else (with their agreement!) please email This email address is being protected from spambots. You need JavaScript enabled to view it. by Friday 26 May. If there is a surplus of nominations for a role, then an online vote will be carried out with the community. Please include the following details in the nomination:
  • Name
  • Position (Councillor/Student Rep.)
  • Nomination Statement (150 words max including a bit about the nominee and your reasons for nominating. This will be circulated to the community in the event of a vote.)
 
MIST Council contact details

Rosie Hodnett - This email address is being protected from spambots. You need JavaScript enabled to view it.
Mathew Owens - This email address is being protected from spambots. You need JavaScript enabled to view it.
Beatriz Sanchez-Cano - This email address is being protected from spambots. You need JavaScript enabled to view it.
Jasmine Kaur Sandhu - This email address is being protected from spambots. You need JavaScript enabled to view it.
Andy Smith - This email address is being protected from spambots. You need JavaScript enabled to view it.
Maria-Theresia Walach - This email address is being protected from spambots. You need JavaScript enabled to view it.
Emma Woodfield - This email address is being protected from spambots. You need JavaScript enabled to view it.
MIST Council email - This email address is being protected from spambots. You need JavaScript enabled to view it.

RAS Awards

The Royal Astronomical Society announced their award recipients last week, and MIST Council would like to congratulate all that received an award. In particular, we would like to highlight the following members of the MIST Community, whose work has been recognised:
  • Professor Nick Achilleos (University College London) - Chapman Medal
  • Dr Oliver Allanson (University of Birmingham) - Fowler Award
  • Dr Ravindra Desai (University of Warwick) - Winton Award & RAS Higher Education Award
  • Professor Marina Galand (Imperial College London) - James Dungey Lecture

Nuggets of MIST science, summarising recent papers from the UK MIST community in a bitesize format.

If you would like to submit a nugget, please fill in the following form: https://forms.gle/Pn3mL73kHLn4VEZ66 and we will arrange a slot for you in the schedule. Nuggets should be 100–300 words long and include a figure/animation. Please get in touch!
If you have any issues with the form, please contact This email address is being protected from spambots. You need JavaScript enabled to view it.. 

Observation of a Fully-formed Forward–Reverse Shock Pair due to the Interaction between Two Coronal Mass Ejections at 0.5 au

By Domenico Trotta (Imperial College London)

The Sun is an active star, responsible for creating a highly dynamic and complex environment, namely the heliosphere. Solar eruptive phenomena are key consequences of such activity, which recently reached the peak of its 11-years cycle, and their study is of paramount importance to understand many unsolved mysteries of how energy is converted in space and astrophysical plasmas [1], as well as to advance our understanding of space weather, for which they are major drivers [2]. Further, novel spacecraft missions, such as Solar Orbiter [3], are opening a novel observational window into such phenomena with revolutionary measurements in the poorly explored inner heliospheric regions close to the Sun.

Solar eruptive phenomena can drive shock waves in the heliosphere (i.e., interplanetary IP shocks), which crucially can be detected in-situ, thus representing the missing link to remote observations of astrophysical systems. Sometimes IP shocks are observed in forward-reverse pairs, propagating away and towards the Sun in the local plasma frame. Forward-reverse shock pairs typically bound compressed plasma regions at solar wind Stream Interaction Regions (SIRs) between slow and fast wind originating from coronal holes [4]. Early observational evidence shows that fully formed forward-reverse shock pairs are very rare in the inner heliosphere, and more commonly observed beyond 1 AU [5]. Conversely, Coronal Mass Ejections (CMEs), the largest eruptive events from the Sun, are routinely found driving forward shocks able to accelerate particles to high energies [6]. Further, interaction between multiple CMEs has been shown as a promising pathway for fast energy conversion in the heliosphere, with a complex range of phenomena being observed in such interaction.

In our study, exploiting the in-situ Solar Orbiter instrument payload, we identified a fully formed forward-reverse shock pair at the unusually short heliocentric distance of 0.5 AU. The observation is shown in Figure 1. We found that such shock pair was not originating from a solar wind SIR, but rather from the interaction between a fast CME interacting with a preceding, slow CME, thereby creating a compression region driving the shock pair due its expansion. This enabled us to study IP shocks in highly unusual parameter regimes (for example the forward shock propagating in CME material). Further, in the interaction region between the two CMEs, a large range of interesting phenomena of energy conversion, such as enhanced rate of magnetic reconnection, has been identified.

We then used remote observations from STEREO-A to identify the two CMEs as they were ejected from the Sun, revealing that the first, slow CME was an extremely faint event. Finally, we used well the radially aligned Wind spacecraft to investigate the fate of such interesting structure, and found that it dissipated at 1 AU, where only a weak forward shock is observed, in stark contrast with SIR-driven shock pairs expected to become stronger with heliocentric distances. Thus, we highlighted how without Solar Orbiter at inner heliocentric distance, such structure would not have been possible to observe and investigate, once again underlining how exploiting multiple heliospheric vantage points is invaluable to advance our understanding of both the Sun-Earth system and remote astrophysical environments.

 
Solar Orbiter direct observation of the forward-reverse shock pair and the interacting CMEs
(full details in the publication).

References:

[1] Rice et al., JGR: Space Physics, 108, 1369 (2003)
[2] Temmer, Liv. Rev. in Sol. Phys., 18, 4 (2021)
[3] Muller et al., A&A, 642, A1 (2020)
[4] Belcher, ApJ, 168, 509 (1971)
[5] Jian et al., Sol. Physics, 239, 337 (2006)
[6] Chen, Liv. Rev. in Sol. Phys., 8, 1 (2011)

See publication for details:
Domenico Trotta et al 2024 ApJL 971 L35
DOI 10.3847/2041-8213/ad68fa 

Temperature anisotropy instabilities driven by intermittent velocity shears in the solar wind

By Simon Opie (Mullard Space Science Laboratory, University College London)

Where and under what conditions the transfer of energy between electromagnetic fields and particles takes place in the solar wind remains an open question. In this paper we resolve to find a quantitative and causative link between turbulence in the solar wind and the occurrence of temperature anisotropy in the proton distribution as measured by Solar Orbiter’s Proton Alpha Sensor (PAS) which is part of the Solar Wind Analyser’s (SWA) suite of instruments. We define and derive the radial rate of strain ΓR as a dynamical measure of the driving of temperature anisotropy by bulk plasma motions. Intervals in the data unstable to the oblique firehose and mirror-mode instabilities are on average characterised by high absolute values of ΓR. We attribute this observation to the proposition that temperature anisotropies associated with these kinetic instabilities are the result of strong, intermittent velocity shears in the turbulent solar wind that cause shearing of the frozen-in magnetic field, with a local double-adiabatic impact on the particle distributions.

 

We show the distribution of ΓR as bin averages in T⊥/T∥–β∥ parameter space, where T is the temperature, β is the ratio of plasma pressure to magnetic pressure, and the subscripts represent measurement of the quantity either perpendicular (⊥) or parallel (||) to the magnetic field. We overplot the instability thresholds for the Oblique Firehose (OF), Alfvén/Ion cyclotron (A/IC), and Mirror-mode (M) instabilities. We see that the areas of parameter space beyond the thresholds for the oblique firehose and mirror-mode instabilities are well defined by extreme values in the distribution of ΓR.

 

See publication for details:
Opie, S., Verscharen, D., Chen, C.H.K., Owen, C.J., Isenberg, P.A., Sorriso-Valvo, L., Franci, L., Matteini, L., 2024. Temperature anisotropy instabilities driven by intermittent velocity shears in the solar wind. 
https://doi.org/10.1017/s0022377824001375

 

Observation of Quiet-Time Mid-Latitude Joule Heating and Comparisons With the TIEGCM Simulation

By Maria-Theresia Walach & Elliot Day (Lancaster University)

Joule heating is a major energy sink in the solar wind-magnetosphere-ionosphere system and modeling it is key to understanding the impact of space weather on the neutral atmosphere. Ion drifts and neutral wind velocities are key parameters when modeling Joule heating, however there is limited validation of the modeled ion and neutral velocities at mid-latitudes. We use the Blackstone Super Dual Auroral Radar Network radar and the Michigan North American Thermosphere Ionosphere Observing Network Fabry-Perot interferometer to obtain the local nightside ion and neutral velocities at ∼40° geographic latitude during the nighttime of 16 July 2014. Despite being a geomagnetically quiet period, we observe significant sub-auroral ion flows in excess of 200 ms−1. We calculate an enhancement to the local Joule heating rate due to these ion flows and find that the neutrals impart a significant increase or decrease to the total Joule heating rate of >75% depending on their direction. As is shown in the figure. Different patches in the ionosphere move at different speeds and therefore create varying Joule heating rates. We compare our observations to outputs from the Thermosphere Ionosphere Electrodynamic General Circulation Model (TIEGCM). At such a low geomagnetic activity however, TIEGCM was not able to model significant sub-auroral ion flows and any resulting Joule heating enhancements equivalent to our observations. We found that the neutral winds were the primary contributor to the Joule heating rates modeled by TIEGCM rather than the ions as suggested by our observations. This presents a gap in TIEGCM's capabilities and care has to be taken when estimating Joule heating rates from models, which make assumptions about ionospheric flows at mid-latitudes.

 

Panels a, b, c, d and e shows the estimated Joule heating components and total heating for each identified patch of
ionospheric flow, the panel labels correspond to the different patch velocities in the paper.
Each component is plotted according to the legend in panel a.
Panel f shows the Joule heating components and total heating modeled by TIEGCM.
Panel g shows the total Joule heating rate calculated as the average heating rate of all patches in the common area,
while re-plotting TIEGCM's total Joule heating in orange for comparison.

See publication for details:

Day, E. K., Grocott, A., Walach, M.-T., Wild, J. A., Lu, G., Ruohoniemi, J. M., & Coster, A. J. (2024). Observation of quiet-time mid-latitude Joule heating and comparisons with the TIEGCM simulation. Journal of Geophysical Research: Space Physics, 129, e2024JA032578. https://doi.org/10.1029/2024JA032578

On the Association of Substorm Identification Methods

 By Christian Lao (UCL, Mullard Space Science Laboratory)

Substorms are a major energy unloading process in the solar wind-magnetosphere-ionosphere system that are capable of processing approximately 10^15J of stored solar wind energy through a complete cycle (Tanskanen et al., 2002). In broad terms, energy is built up and stored in the magnetosphere during substorm growth phases by enhanced reconnection between the solar wind and the magnetosphere on the dayside. Energy is released during substorm expansion and recovery phases by reconnection and other plasma instabilities in the magnetotail, with the start of the expansion phase known as substorm onset. Over the years, numerous signatures and techniques have been used to identify substorm onsets, but these are typically developed or used in isolation. In this study, we quantify the association between the different signatures used for identification of substorms (more specifically, substorm onset). Generally, we found that methods developed and applied to ground magnetometer data achieved the best associations, with events identified at mid-latitude (Chu et al., 2015) and at auroral latitudes (Newell & Gjerloev, 2011) showing the highest levels of coincidence with other substorm indicators. On the other hand, we found that events identified by particle injections (Borovsky & Yakymenko, 2017) showed much poorer associations with other substorm lists, in particular with no improvement over chance agreement with events identified from the aurora. Remarkably, we found less than 50% agreement on the timing and occurrence of substorms between any of the lists studied. As such, any studies dependent upon such lists may come to premature conclusions about substorm dynamics or impacts. Furthermore, a significant number of events in each list may not share multiple substorm signatures, calling into question the legitimacy of each identification. This highlights the need to further cross calibrate our methods or use multiple signatures to evaluate a more robust set of events.

              

          True positive rate “heatmap” showing the percentage of events from the Reference (Horizontally labelled)
                  substorm list a Comparison substorm list (Vertically labelled) also observes. These are the best
     performing methods on the datasets they are leveraging. A higher score/lighter colour indicates better association.

References:
Tanskanen et al. 2002: https://doi.org/10.1029/2001JA900153
Chu et al., 2015: https://doi.org/10.1002/2015JA021104
Newell & Gjerloev, 2011: https://doi.org/10.1029/2011JA016779
Borovsky & Yakymenko, 2017: https://doi.org/10.1002/2016JA023625

See publication for details:

Lao, C. J., Forsyth, C., Freeman, M. P., Smith, A. W., & Mooney, M. K. (2024). On the association of substorm identification methods. Journal of Geophysical Research: Space Physics, 129, e2024JA032762. https://doi.org/10.1029/2024JA032762

 

The relative prevalence of wave-packets and coherent structures in the inertial and kinetic ranges of turbulence as seen by Solar Orbiter

By Alina Bendt (CFSA, University of Warwick)

The in-situ measurements of the solar wind by Solar Orbiter provide the opportunity to study turbulence at very high Reynolds numbers in a nearly collissionless plasma. Turbulence is a potential contributor to the heating, structure, and dynamics of the solar wind. With Solar Orbiter it is now possible to study the evolution of solar wind turbulence. We use Solar Orbiter observations of nine extended intervals of homogeneous turbulence to determine under what conditions turbulent magnetic field fluctuations may be characterized as: (i) wave-packets and (ii) coherent structures. We perform the first systematic scale-by-scale decomposition of the magnetic field using two wavelets known to resolve wave-packets and discontinuities, the Daubechies 10 and Haar respectively. We compare the functional forms of the fluctuation probability distributions obtained from these wavelet decompositions via quantile-quantile plots. The comparison of the fluctuation pdfs between the two wavelets reveals three distinct regimes of behaviour and establishes a crossover range between wave-packet and coherent structure phenomenology in the inertial and kinetic ranges. The crossover range is seen to exhibit a distinct 2-component functional form. And the behaviour of the crossover range depends on the heliocentric distance and field alignment angle. As coherent structures and wave-wave interactions are both candidates to mediate the turbulent cascade, these results offer new insights into the distinct physics of the inertial and kinetic ranges.

 

             Probability distribution functions (pdfs) comparison between Haar and Db10 wavelet decompositions of the magnetic field. Pdfs are shown for $B_{\perp (V_{sw}\times B)}$ for four example intervals (rows). The chosen intervals (top down) are at $0.989$ au with $\beta=0.95$ and $\theta=18.07$°, at $0.934$ au with $\beta=2.08$ and $\theta=160.93$°, at $0.597$ au with $\beta=2.48$ and $\theta=68.63$°, and at $0.37$ au with $\beta=0.76$ and $\theta=16.82$°. The scales shown are increasing from left to right at $0.25$, $0.5$, $2$ and $8$ s. Empty purple circles are obtained from the Db10 wavelet decomposition, while green circles are from the Db10 wavelet decomposition. The pdfs are normalised by bin width and overall number of samples of magnetic field data. The number of bins is scaled by the standard deviation $\sigma$ at the corresponding scale and bins with less than $10$ counts are discarded. The error is estimated as $\sqrt{n}$, where $n$ is the bin count, error bars are too small to be resolved visually.

            Probability distribution functions (pdfs) comparison between Haar and Db10 wavelet
            decompositions of the magnetic field. Pdfs are shown for Bperp(Vsw ⋅ B)} for four
            example intervals (rows). The chosen intervals (top down) are at 0.989 au with β=0.95
            and θ=18.07°, at 0.934 au with β=2.08 and θ=160.93°, at 0.597 au with β=2.48 and θ=68.63°,
            and at 0.37 au with β=0.76 and θ=16.82°. The scales shown are increasing from left to right
            at 0.25, 0.5, 2 and 8 s. Empty purple circles are obtained from the Db10 wavelet decomposition,
            while green circles are from the Db10 wavelet decomposition. The pdfs are normalised by bin
            width and overall number of samples of magnetic field data. The number of bins is scaled by
            the standard deviation σ at the corresponding scale and bins with less than 10 counts are
            discarded. The error is estimated as √n, where ν is the bin count, error bars are too small to
            be resolved visually.

 

See publication for further information: 

Bendt, A., Chapman, S. C., Dudok de Wit, T. (2024). The relative prevalence of wave packets and coherent structures in the inertial and kinetic ranges of turbulence as seen by Solar Orbiter. The Astrophysical Journal, 971:179.
https://iopscience.iop.org/article/10.3847/1538-4357/ad54bc