MIST

Magnetosphere, Ionosphere and Solar-Terrestrial

Latest news

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

New MIST Council 2021-

There have been some recent ingoings and outgoings at MIST Council - please see below our current composition!:

  • Oliver Allanson, Exeter (This email address is being protected from spambots. You need JavaScript enabled to view it.), to 2024 -- Chair
  • Beatriz Sánchez-Cano, Leicester (This email address is being protected from spambots. You need JavaScript enabled to view it.), to 2024
  • Mathew Owens, Reading (This email address is being protected from spambots. You need JavaScript enabled to view it.), to 2023
  • Jasmine Sandhu, Northumbria (This email address is being protected from spambots. You need JavaScript enabled to view it.), to 2023 -- Vice-Chair
  • Maria-Theresia Walach, Lancaster (This email address is being protected from spambots. You need JavaScript enabled to view it.), to 2022
  • Sarah Badman, Lancaster (This email address is being protected from spambots. You need JavaScript enabled to view it.), to 2022
    (co-opted in 2021 in lieu of outgoing councillor Greg Hunt)

Charter amendment and MIST Council elections open

Nominations for MIST Council open today and run through to 8 August 2021! Please feel free to put yourself forward for election – the voting will open shortly after the deadline and run through to the end of August. The positions available are:

  • 2 members of MIST Council
  • 1 student representative (pending the amendment below passing)

Please email nominations to This email address is being protected from spambots. You need JavaScript enabled to view it. by 8 August 2021. Thank you!

Charter amendment

We also move to amend the following articles of the MIST Charter as demonstrated below. Bold type indicates additions and struck text indicates deletions. Please respond to the email on the MIST mailing list before 8 August 2021 if you would like to object to the amendment; MIST Charter provides that it will pass if less than 10% of the mailing list opposes its passing. 

4.1  MIST council is the collective term for the officers of MIST and consists of six individuals and one student representative from the MIST community.

5.1 Members of MIST council serve terms of three years, except for the student representative who serves a term of one year.

5.2 Elections will be announced at the Spring MIST meeting and voting must begin within two months of the Spring MIST meeting. Two slots on MIST council will be open in a given normal election year, alongside the student representative.

5.10 Candidates for student representative must not have submitted their PhD thesis at the time that nominations close.

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.. 

Weak Turbulence and Quasilinear Diffusion for Relativistic Wave-Particle Interactions Via a Markov Approach

By Oliver Allanson (Exeter University)

Quasilinear diffusion theory forms the basis of much of the modelling and interpretation of particle transport and energization due to interactions with electromagnetic waves; at terrestrial and planetary radiation belts; in the solar atmosphere and solar wind; and for the dynamics of cosmic rays.

We present a derivation of weak turbulence and quasilinear diffusion theories in energy and pitch-angle space that differs from the most standard methods of derivation (based upon the Vlasov equation [1]). We

  1. start from solutions to the single-particle Lorentz force equation
  2. expand the relevant equations of motion up to second order in a small parameter (magnitude of magnetic perturbations to background field)
  3. ensemble average the solutions to obtain the diffusion coefficients.

The approach used in this paper builds upon the work by [2], in which only pitch-angle dynamics were considered.

The main conclusions and results of this paper are as follows:

  1. A derivation and discussion of the general Fokker-Planck equation to describe stochastic charged particle dynamics. This equation includes all possible advective and diffusive dynamics, in principle. The form of the drift and diffusion coefficients are then to be determined on a system-by-system basis. We solve for the diffusive dynamics only, and leave investigations of the drift coefficients and drift-diffusion relations for future works
  2. The weak turbulence diffusion coefficients: i) display an interesting dependency on time (see Figure1); ii) and also explicitly incorporate the effects of non-resonant particles, as well as the standard effects of cyclotron-resonant particles
  3. We recover the standard form as used in the resonant-diffusion limit of relativistic quasilinear theory [3], when we consider elapsed timescales much greater than a gyroperiod
  4. Our new derivation has a number of benefits, including: 1) the relationship between a more general weak turbulence theory and the standard resonant diffusion quasilinear; 2) the general nature of the Fokker-Planck equation that can be derived without any prior assumptions regarding its form; 3) the clear dependence of the form of the Fokker-Planck equation and the transport coefficients on given specific timescales.

Figure showing time-dependency is relevant for diffusion.

 See paper for full details: Allanson O, Elsden T, Watt C and Neukirch T (2022) Weak Turbulence and Quasilinear Diffusion for Relativistic Wave-Particle Interactions Via a Markov Approach.  Front. Astron. Space Sci. 8:805699. doi: 10.3389/fspas.2021.805699 

 

1: C. F. Kennel and F. Engelmann , "Velocity Space Diffusion from Weak Plasma Turbulence in a Magnetic Field", The Physics of Fluids 9, 2377-2388 (1966)

2: Don S. Lemons , "Pitch angle scattering of relativistic electrons from stationary magnetic waves: Continuous Markov process and quasilinear theory", Physics of Plasmas 19, 012306 (2012)

3: Glauert, S. A., and Horne, R. B. (2005), Calculation of pitch angle and energy diffusion coefficients with the PADIE code, J. Geophys. Res., 110, A04206

 

Magnetopause ripples going against the flow form azimuthally stationary surface waves

By Martin Archer (Imperial College London)

Like waves on water, surface waves on the outer boundary of Earth’s magnetosphere, the magnetopause are thought to always travel in the direction of the driving solar wind. Indeed, many observations of the global dynamics of the magnetosphere show that disturbances travel tailward, i.e. with the wind, for both steady and impulsive driving. However, we find that the lowest-frequency magnetopause surface waves, which form standing waves along the terrestrial magnetic field, actually propagate against the flow outside the boundary.

Multi-spacecraft observations of the resonant surface waves excited by an isolated magnetosheath jet show that the speed of the waves’ energy flow is comparable, but in opposition, to the magnetosheath velocity. Global MHD simulations of the magnetospheric response to a pressure pulse reveal the inward/outward boundary motion is azimuthally stationary across a wide local time range (09-15h). This is despite significant flows being present that should otherwise advect the waves tailward. We show in the figure this is possible since the surface waves’ Poynting flux (panel a) exactly balances the flow's advective effect (panel b) leading to no net energy flux (panel c) over this local time range. Further down the equatorial flanks, however, advection dominates hence the waves travel downtail, seeding fluctuations at the resonant frequency which subsequently grow in amplitude via the Kelvin-Helmholtz instability. Our findings are also in excellent agreement with simple analytic theory. We, therefore, illustrate our overall conclusions in the right panel of the figure.

These unexpected results reveal that magnetopause surface waves can persist longer than was previously expected, which will have implications upon radiation belt, ionospheric, and auroral dynamics. Furthermore, since surface waves drive dynamics in many space, astrophysical and laboratory plasma systems, the results made possible by in situ measurements, may have applications to other environments where these are not possible, for example coronal loops.

Figure showing surface wave energy fluxes tangential to the magnetopause.
Figure: Surface wave energy fluxes tangential to the magnetopause. Panels show the Poynting (a) and advective (b) energy fluxes tangential to the magnetopause along magnetopause normals. Integrals along the normal are shown in panel c for the Poynting (purple) and advective (green) fluxes along with their sum (black). On the right an animation of the global dynamics is shown (credit Martin Archer / Emmanuel Masongsong / NASA).

Please see paper for full details: Archer, M.O., Hartinger, M.D., Plaschke, F. et al. Magnetopause ripples going against the flow form azimuthally stationary surface waves. Nat Commun 12, 5697 (2021). https://doi.org/10.1038/s41467-021-25923-7

The Roles of the Magnetopause and Plasmapause in Storm-Time ULF Wave Power Enhancements

By Jasmine Kaur Sandhu (Northumbria University)

The Earth’s magnetosphere experiences extreme and dramatic changes during geomagnetic storms due to strongly enhanced solar wind conditions. One impact of the elevated solar wind conditions is the increased occurrence and amplitude of Ultra Low Frequency (ULF) waves across the dayside magnetosphere. These ULF waves are of particular interest due to their implications for transporting and coupling energy within the magnetosphere. However, the radial distribution of ULF wave power is complex – controlled interdependently by external solar wind driving and the internal magnetospheric structuring.

In this study, we explored how ULF wave power is distributed radially in the dayside magnetosphere. We conducted a statistical analysis of storm-time ULF wave power observations from the Van Allen Probes. The results showed that accounting for the plasmapause and (especially) the magnetopause locations reduce statistical variability and improve parameterisation of spatial trends over and above using the L value, highlighting the importance of these boundaries in controlling where and when enhanced ULF wave power is present.

A key finding was the importance of local plasma density. We find that during geomagnetic storms, high density patches in the afternoon sector (e.g. plasmaspheric plumes) act to “trap” ULF waves, leading to spatially localised patches of very high ULF wave power. Figure 1 shows one example of high ULF wave power confined within a patch of enhanced density. The results have critical implications for understanding how ULF waves propagate within the terrestrial magnetosphere, and highlights the importance of the highly distorted storm-time cold plasma density distribution on wider geomagnetic processes.

A multi-panel plot showing time series of Van Allen Probes observations during an event.

Figure 1. Timeseries for 27 August 2015 showing the (a) Sym-H index [nT], (b) Earthward component of the solar wind speed, |vX| [km s-1], and (c) Southward IMF component, BZ [nT]. Panels (d-i) show time series for the Van Allen Probes A (pink) and B (blue). We show (d) L value and (e) MLT [h] of the spacecraft location, and (f) total electron density, ne [cm-3]. Panels (g) and (h) show power, P(f) [nT2 Hz-1], as a function of frequency, f [mHz], and time for Probe A and Probe B, respectively. Panel (i) shows the power, P [nT2 Hz-1], summed over the ULF wave band.

Please see the paper for full details:

Sandhu, J. K., Rae, I. J., Staples, F. A., Hartley, D. P., Walach, M.-T., Elsden, T., & Murphy, K. R. (2021). The Roles of the Magnetopause and Plasmapause in Storm-Time ULF Wave Power Enhancements. Journal of Geophysical Research: Space Physics, 126, e2021JA029337. https://doi.org/10.1029/2021JA029337

Geosynchronous magnetopause crossings and their relationships with magnetic storms and substorms

By Andrey Samsonov (Mullard Space Science Laboratory - University College London)

 

Strengthening of magnetospheric activity is often preceded by a strong magnetospheric compression. For example, interplanetary coronal mass ejections (ICMEs) which may result in geomagnetic storms often begin with interplanetary shocks and corresponding storm sudden commencements in ground data. We investigate relations between magnetospheric compressions and magnetospheric activity in terms of the indices of magnetospheric activity (Dst, SuperMAG SML and SMU, Kp, PC). We make a list of geosynchronous magnetopause crossings (GMCs) using OMNI data and Lin et al.’s (2010) empirical model. We study which solar wind conditions accompany GMC events and which changes of the geomagnetic indices follow GMCs. We also find out which solar wind drivers result in the GMCs. Using ICME and corotating interaction regions (CIR) catalogues, we classify 74 (of 99) events as ICMEs and 18 events as stream interaction regions (SIRs) or corotating interaction regions. Furthermore, we have found that 76 GMCs follow interplanetary shocks.

During the first GMC hour, the hourly average solar wind density is usually high (larger than 20 cm-3in 70 % cases), and the hourly interplanetary magnetic field (IMF) Bis negative (in 87 % cases). Over all events the average SMU (SML), Kp, and PC indices reach maxima (minima) in 1 hour after the GMC beginning, while the delay of the minimum of the Dst index is usually 3-8 hours. These average time delays do not depend on the strength of the storms and substorms. The SML (Dst) minimum is less than -500 nT (-30 nT) in the next 24 hours in 95 % (99 %) cases, i.e., the GMC events are mostly followed by magnetic storms and substorms. We compare solar wind and magnetospheric conditions for GMCs connected with ICMEs and SIRs. Our study confirms that the ICME-related events are characterized by stronger ring current and auroral activity than the SIR-related events. The difference might be explained by the different behavior of the solar wind velocity because the velocity at t=0 (the first GMC time) is higher for the ICME-related events (see Figure 1).

Solar wind conditions for the ICME-related (left) and SIR-related (right) events in the interval from 3 hours before to 24 hours after the first GMCs.
Figure 1. Solar wind conditions for the ICME-related (left) and SIR-related (right) events in the interval from 3 hours before to 24 hours after the first GMCs. Thick black lines indicate average parameters.

Please see the paper for full details:

Samsonov, A. A., Bogdanova, Y. V., Branduardi-Raymont, G., Xu, L., Zhang, J., Sormakov, D., et al. (2021). Geosynchronous magnetopause crossings and their relationships with magnetic storms and substorms. Space Weather, 19, e2020SW002704. https://doi.org/10.1029/2020SW002704.

The Importance of Sudden Commencements in Causing Elevated Ground Magnetic Field Variability

By Andy Smith (Mullard Space Science Laboratory - University College London)

Large variability in the Earth’s magnetic field can induce anomalous and damaging currents in power systems and pipelines.  It is crucial that we understand and can predict the processes responsible.  In this work we quantified how Sudden Commencements (SCs) contribute to creating large rates of change of the surface magnetic field.  SCs are caused by the impact of solar wind pressure pulses, e.g. interplanetary shocks, on the Earth’s magnetosphere.  They represent one of the more reliably forecastable forms of space weather, where the driving solar wind structure can be observed upstream of the Earth prior to its arrival.

 

We found that SCs are related to enhanced rates of change of the ground magnetic field (R).  The Figure below shows the fraction of R in excess of 50 nTmin-1 that is related to SCs, as a function of latitude.  The top panel shows the percentage observed during the SCs themselves.  This maximises at around 20 – 30% at low latitudes, but drops to <1% by around 55° as other processes become fractionally more important at generating large R.

 

SCs often precede further magnetospheric activity, such as geomagnetic storms and substorms.  The lower panel below shows the statistics for the time period during SCs, while also including the 24 hours that follow.  This extended period can be seen to account for around 75% of large R (in excess of 50 nTmin-1) at locations below ~55°.

 

This work has shown that SCs are an important source of potentially hazardous magnetic field perturbations, and proportionally they are more important at mid-to-low latitudes.  Usefully, SCs also provide a 24 hour window within which the majority (~75%) of large rates of change of the field are observed, below ~55 degrees latitude.

 Percentage of sudden commencement oberservations

Figure 1: The percentage of observations of R ≥ 50 nT min−1 (1996 - 2016) that can be related to SCs as a function of magnetic latitude. The rows represent the data obtained during the SCs themselves (i), 
and the data inclusive of 24 hours following the SC (ii).

 

Please see the paper for full details:

Smith, A. W., Forsyth, C., Rae, I. J., Rodger, C. J., & Freeman, M. P. (2021). The Impact of Sudden Commencements on Ground Magnetic Field Variability: Immediate and Delayed Consequences. Space Weather, 19, e2021SW002764. https://doi.org/10.1029/2021SW002764