MIST

Magnetosphere, Ionosphere and Solar-Terrestrial

Latest news

New mailing list for Python in space science

A new mailing list for space scientists who use Python has been founded. Angeline Burrell writes: 

There's been a recent push for more community python development and peer-to-peer support. Much of this is focused in the US at the moment, but as the results of the recent survey showed, MIST scientists are active or interested in python as well. If you would like to become involved, you can join the email list by contacting This email address is being protected from spambots. You need JavaScript enabled to view it..

The mailing list will comprise discussion as well as webinars/telecons from Python users, so the list should be useful for a range of abilities with Python. To join, please email This email address is being protected from spambots. You need JavaScript enabled to view it..

New MIST forum via Slack

In the days of yesteryear, there was a MIST forum provided for members of the MIST community to discuss things in a fashion more immediate and informal than email. It has been some years since the fabled MIST forum was a going concern, and in that time, the MIST Council has technically been in violation of the MIST Charter, which states that

MIST will provide an on-line forum to allow ongoing discussions and the formulation of ideas prior to public dissemination. This forum will be private, visible only to registered members; membership is restricted to active MIST scientists and is offered at the discretion of MIST council chair.

As a result of realising that the Charter mandates the maintenance of a forum, MIST Council have chosen to create a Slack workspace for the MIST community. If you would like to join, please This email address is being protected from spambots. You need JavaScript enabled to view it. specifying the email address you would like to use, and you will be invited to join.

MIST Council election results

The polls have closed, and Oliver Allanson (Reading) and John Coxon (Southampton) have been elected to MIST Council. The full results of 2018’s elections are as follows:

  • Oliver Allanson: 56 votes
  • John Coxon: 100 votes
  • Simon Pope: 27 votes
  • Samuel Wharton: 38 votes
  • Darren Wright: 40 votes

121 people cast two votes, and 19 cast a single vote, for a total of 140 responses. This is a turnout of 32.9% against the MIST mailing list, which comprises 426 eligible voters.

The chair of MIST Council, Ian McCrea, said:

I would like to congratulate John on his re-election to MIST Council and to congratulate Oliver on his election – we look forward to you joining us at our next meeting. To the unsuccessful candidates, I would like to say a sincere thank you for taking part and for your interest in being part of MIST Council. Obviously only two candidates can be successful in any given year, but there are elections every year and we hope that you will not be discouraged from standing again at a future date.

MIST Council would like to express their thanks and appreciation to Luke Barnard who is leaving MIST Council, and whose contributions over the last three years have been invaluable. We would also like to thank Q Stanley for handling the technical aspects of the election.

Astronomy/Solar System Advisory Panels call for priority projects

The Astronomy and Solar System Advisory Panels have been asked to identify a few priority projects, comprising 'large scale' (>£50M), ‘medium scale’ (£10-50M) and ‘small scale’ (<£10M) projects that can be started within the next 6 years. The outline business cases put forward by the community will be considered by STFC’s Executive Board and Science Board in September. We will then work with the community and UKRI to identify the best way of taking these ideas forward. 

Interested parties should summarize their ideas for priority projects using the template provided. Only those projects considered to be the most exciting and highest priority (by the Advisory Panels) will be asked to develop an outline business case. Please email your project summary to This email address is being protected from spambots. You need JavaScript enabled to view it. (Astronomy) or This email address is being protected from spambots. You need JavaScript enabled to view it. (Solar System). If your project has overlap with both astronomy and solar system, then please indicate this in your summary and send to both panels. The deadline is Wednesday 18 July 2018. If you have any questions regarding remit, format or submission, please feel free to contact the relevant Advisory Panel.

Jonathan Eastwood wrote, in his email to the MIST mailing list:

STFC has launched a consultation with research communities, designed to identify new world class science and technology proposals for potential future investment. The aim is to develop an ambitious portfolio of outline business cases for priority projects that relate to our strategic scientific and research infrastructure objectives, covering our remit, and driven by our communities… the scope of the projects is very broad – what is needed are exciting and ambitious scientific projects within the broad remit of astronomy and solar system science. Funds for estates and campus development are out of scope, and projects should not be an uplift to the grant/fellowship lines. This exercise is not part of the Evaluation of Astronomy which STFC will undertake in the Autumn (part of its assessment of the wider astronomy, particle and nuclear physics programmes), but projects identified here will be forwarded to that exercise to ensure information is not lost.

MIST Council would like to urge members of the MIST community to engage with this exercise in order to make sure that MIST science is well-represented in STFC strategy in the future.

Petition to eliminate harassment and bullying

MIST council is committed to fostering an open and inclusive scientific environment.

Many people will have seen the recent reports of bullying and harassment in Universities are becoming more and more widespread. In one of many steps to highlight the need for these actions to stop, an open letter and petition has been prepared by members of the wider community, including faculty from Imperial, UCL, and other UK and international institutions. This cross-institute example underlines the importance of eliminating harassment and bullying from the university and research environments. If you wish to sign the petition, you can find it by clicking here.

Our community is a big part of the RAS, which has a Code of Conduct and a Diversity, Equality and Inclusion Policy that we must adhere to:

  1. Promoting an inclusive environment for all.
    2. Promoting equality of opportunity.
    3. Welcoming applications from all backgrounds.
    4. Supporting and developing careers for all.
    5. Recruiting and promoting staff based on merit, rather than absence or presence of underrepresented characteristics.

We would strongly encourage our community to continue to participate in eradicating these issues from our scientific and every day lives.

School students discover sounds caused by solar storms

By Martin Archer, School of Physics and Astronomy, Queen Mary University of London, UK.

Earth’s magnetic shield is rife with a symphony of ultra-low frequency analogues to sound waves. These waves transfer energy from outside this shield to regions inside it and therefore play a key role in space weather - how space poses a risk to our everyday lives by affecting power grids, GPS, passenger airlines, mobile telephones etc.

While these waves are too low pitch for us to hear them, Archer et al. [2018] show that we can make our satellite recordings of them audible by dramatically speeding up their playback. These audio versions of the data can be used by school students to contribute to research, by having them explore the data through the act of listening and performing analysis using audio software.

An example of this is presented where school students from Eltham Hill School in London identified “whistling” sounds whose pitch decreased over the course of several days. This event started when a coronal mass ejection, or solar storm, arrived at Earth causing a big disturbance to the space environment. It turned out that the whistling sounds were vibrations of Earth’s magnetic field lines, a bit like the vibrations of a guitar string which form a well-defined note. While the solar storm stripped away much of the material present in Earth’s space environment, as it started to recover following the storm, this started to refill again. It was this refilling that caused the pitch of the sounds to drop slowly over time.

Previously events like these had barely been discussed and therefore were thought to be rare. However, many similar events were discovered in the audio which also followed similar disturbances, revealing that these types of waves are much more common than previously thought.

Video: https://www.youtube.com/watch?v=X6vbST9iMOU

For more information, please see the paper below:

Archer, M.O., M.D. Hartinger, R. Redmon, V. Angelopoulos, and B. Walsh. (2018), First results from sonification and exploratory citizen science of magnetospheric ULF waves: Long‐lasting decreasing‐frequency poloidal field line resonances following geomagnetic storms, Space Weather, 16, https://doi.org/10.1029/2018SW001988

Untangling the periodic ‘flapping’ and ‘breathing’ behaviour of Saturn’s equatorial magnetosphere

By Arianna Sorba, Department of Physics and Astronomy, University College London, UK.

At Saturn, the planet’s rotation axis and the dipole axis are aligned to within 0.01° [Dougherty et al., 2018], and so the magnetosphere’s magnetic field should be extremely azimuthally symmetric. However the Cassini space mission, which orbited Saturn from 2004-2017, observed mysterious periodic variations in the magnetic field at a period close to the planetary rotation rate. These observations suggested that the outer magnetosphere’s equatorial current sheet was `flapping’ above and below the rotational equator once per planetary rotation, to a first approximation acting like a rotating, tilted disc [Arridge et al., 2011].

However this ‘flapping’ picture does not fully explain the observed magnetic field periodicities. More recently, some studies have suggested the magnetosphere may also display ‘breathing’ behaviour; a periodic large-scale compression and expansion of the system, associated with a thickening and thinning of the current sheet [Ramer et al., 2016, Thomsen et al., 2017]. In Sorba et al. [2018], we investigate these two dynamic behaviours in tandem by combining a geometric model of a tilted and rippled current sheet, with a force-balance model of Saturn’s magnetodisc. We vary the magnetodisc model system size with longitude to simulate the breathing behaviour, and find that models that include this behaviour agree better with the observations than the flapping only models. This can be seen in the figure below, which shows that for an example Cassini orbit, both the amplitude and phase of the magnetic field variations are better characterised by the flapping and breathing model, especially for the meridional component (middle panel).

The underlying cause of this periodic dynamical behaviour is still an area of active research, but is thought to be due to two hemispheric magnetic field perturbations rotating at different rates. The study by Sorba et al. [2018] provides a basis for understanding the complex relationship between these perturbations and the observed current sheet dynamics.

For more information, please see the paper below:

Sorba, A.M., N. Achilleos, P. Guio, C.S. Arridge, N. Sergis, and M.K. Dougherty. (2018), The periodic flapping and breathing of Saturn's magnetodisk during equinox, J. Geophys. Res. Space Physics, 123. https://doi.org/10.1029/2018JA025764

Figure: Radial (a), meridional (b), and azimuthal (c) components of the magnetic field measured by Cassini along Rev 120 Inbound. Magnetometer data shown in black, flapping only model shown in red, and flapping and breathing model shown in blue. Annotation labels underneath the time axis give the cylindrical radial distance of Cassini from the planet centre, and Saturn magnetic local time.

 

Energetic particle showers over Mars from Comet C/2013 A1 Siding-Spring

By Beatriz Sánchez-Cano, Department of Physics and Astronomy, University of Leicester, UK.

On the 19th October 2014, an Oort-cloud comet named Comet C/2013 A1 (Siding Spring) passed Mars at an altitude of 140,000 kilometres (only one third of the Earth-moon distance) during a single flyby through the inner solar system. This rare opportunity, where an event of this kind occurs only once every 100,000 years, prompted space agencies to coordinate multiple spacecraft to witness the largest meteor shower in modern history and allow us to observe the interaction of a comet’s coma with a planetary atmosphere. However, the event was somehow masked by the impact of a powerful Coronal Mass Ejection from the Sun that arrived at Mars 44 hours before the comet, creating very large disturbances in the Martian upper atmosphere and complicating the analysis of data.

Sánchez-Cano et al. [2018] present energetic particle datasets from the Mars Atmosphere and Volatile EvolutioN (MAVEN) and the Mars Odyssey missions to demonstrate how the Martian atmosphere reacted to such an unusual external event. Comets are believed to have strongly affected the evolution of planets in the past and this was a near unique opportunity to assess whether cometary energetic particles, in particular O+, constitute a notable energy input into Mars’ atmosphere. The study found several Odetections while Mars was within the comet’s environment (at less than a million kilometers distance, see period A in the figure below). In addition, the study discusses several other very interesting showers of energetic particles that occurred after the comet’s closest approach, which are also indicated in the figure below. These detections seem to be related to comet dust tail impacts, which were previously unnoticed. This unexpected detections strongly resemble the tail observations that EPONA/Giotto made of comet 26P/Grigg-Skjellerup in 1992. In conclusion, the authors found that the comet produced a large shower of energetic particles into the Martian atmosphere, depositing a similar level of energy to that of a large space weather storm. This suggests that comets had a significant role on the evolution of the terrestrial planet’s atmospheres in the past.

For more detailed information, please go to the paper:

Sánchez – Cano, B., Witasse, O., Lester, M., Rahmati, A., Ambrosi, R., Lillis, R., et al (2018). Energetic Particle Showers over Mars from Comet C/2013 A1 Siding‐Spring. Journal of Geophysical Research: Space Physics, 123.https://doi.org/10.1029/2018JA025454

Figure: MAVEN and Mars Odyssey observations as a function of time of a powerful Coronal Mass Ejection on 17th October 2014, and of comet Siding-Spring flyby on 19th October 2014. It can be seen that from the point of view of energetic particles, the comet deposited a similar amount of energy than a solar storm on Mars’ atmosphere. (a) MAVEN-SEP ion energy spectra  (b) Mars Odyssey-HEND energy profile from higher-energy channels. (c) Same as in (b) but for lower-energy channels. Periods A and B indicate the comet O+ detections at Mars. Period C shows similar detections although the particle identity cannot be determined. Finally, periods D and E shows dust tail impacts on the instrument.

The dependence of solar wind burst size on burst duration and its invariance across solar cycles 23 and 24

By Liz Tindale, CFSA, Department of Physics, University of Warwick, UK.

Time series of solar wind variables, such as the interplanetary magnetic field strength, are characteristically “bursty”: they take irregularly spaced excursions to values far higher than their average [Consolini et al., 1996; Hnat et al., 2002]. These bursts can be associated with a range of physical structures, from coronal mass ejections [Nieves-Chinchilla et al., 2018] and corotating interaction regions [Tsurutani et al., 2006] on large scales, down to small-scale transient structures [Viall et al., 2010] and turbulent fluctuations [Pagel and Balogh, 2002]. Over the course of the 11-year solar cycle, changing coronal activity causes the prevalence of these structures in the solar wind to vary [Behannon et al., 1989; Luhmann et al., 2002]. As energetic bursts in the solar wind are often the drivers of increased space weather activity [Gonzales et al., 1994], it is important to understand their characteristics and likelihood, as well as their variation over the solar cycle and between cycles with different peak activity levels.

Tindale et al. [2018] use data from NASA’s Wind satellite to study bursts in the time series of solar wind magnetic energy density, Poynting flux, proton density and proton temperature during 1-year intervals around the minima and maxima of solar cycles 23 and 24. For each variable, the duration of a burst and its integrated size are related via a power law; the scaling exponent of this power law is unique to each parameter, but importantly is invariant over the two solar cycles. However, the statistical distributions of burst sizes and durations do change over the solar cycle, with an increased likelihood of encountering a large burst at solar maximum. This indicates that while the likelihood of observing a burst of a given size varies with solar activity, its characteristic duration will remain the same. This result holds at all phases of the solar cycle and across a wide range of event sizes, thus providing a constraint on the possible sizes and durations of bursts that can exist in the solar wind.

For more information, please see the paper below:

Tindale, E., S.C. Chapman, N.R. Moloney, and N.W. Watkins (2018), The dependence of solar wind burst size on burst duration and its invariance across solar cycles 23 and 24, J. Geophys. Res. Space Physics, 123, doi:10.1029/2018JA025740.

Figure: Scatter plots of burst size, S, against burst duration, τD, for bursts in the time series of solar wind magnetic energy density, B2, extracted from one-year time series spanning i) the minimum of solar cycle 23, ii) the cycle 23 maximum, iii) the minimum of cycle 24, and iv) the cycle 24 maximum. The colours denote bursts extracted over increasingly high thresholds: the 75th, 85th and 95th percentiles of each B2 time series. The solid black line shows the regression of log10(S) onto log10(τD) for bursts over the 85th percentile threshold; the gradient of the regression for bursts over each threshold, alongside the 95% confidence interval, is denoted by α.

Intense electric fields and electron-scale substructure within magnetotail flux ropes as revealed by the Magnetospheric Multiscale mission

By Julia E. Stawarz, Department of Physics, Imperial College London, UK.

In Stawarz et al. [2018], we examine large- and small-scale properties of three ion-scale flux ropes in Earth’s magnetotail. Evidence of variability in the flux rope orientations is found and an electron-scale vortex is discovered inside one of the flux ropes. 

Magnetic reconnection, which releases stored magnetic energy and converts it into particle motion, is a key driver of dynamics in Earth’s magnetosphere. However, it is still not fully understood how particles are accelerated and energy is partitioned both within the reconnection diffusion region, where particles decouple from the magnetic field, and within reconnection outflows. Helical magnetic fields known as flux ropes are one type of structure generated by reconnection and often observed within reconnection outflows [Borg et al., 2012; Eastwood & Kiehas, 2015; Sharma et al., 2008], which are both theoretically [Drake et al., 2006; Dahlin et al., 2017] and observationally [Chen et al., 2008] linked with particle energization. Previous observations have shown flux ropes can have substructure and intense electric fields [e.g., Eastwood et al., 2007], but the nature of these electric fields have not been previously determined. Recent high-time-resolution, mutispacecraft measurements with electron-scale separations from NASA’s Magnetospheric Multiscale (MMS) mission finally allow us to examine the detailed substructure of flux ropes.

The three closely spaced flux ropes examined in Stawarz et al. [2018] are observed near a reconnection diffusion region and have different orientations, indicating significant spatiotemporal variability and highlighting the three-dimensional nature of the overall reconnection event. One of the most intense electric fields in the event is found within one of the flux ropes and is linked with an electron vortex (Fig. 1). The intense electric field is perpendicular to the magnetic field and the vortex consists of electrons that are frozen-in and ions that are decoupled from the fields. The resulting difference in motion between the ions and electrons drifting in the electromagnetic fields drives a current perpendicular to the magnetic field that produces a small-scale magnetic enhancement. The presence of such vortices may contribute to accelerating particles, either through inferred parallel electric fields at the ends of the structure or the excitation of waves, and points to the necessity of better understanding the substructure of flux ropes in order to characterize particle energization in magnetic reconnection.

For more information, see our paper below:

Stawarz, J. E., J. P. Eastwood, K. J. Genestreti, R. Nakamura, R. E. Ergun, D. Burgess, J. L. Burch, S. A. Fuselier, D. J. Gershman, B. L. Giles, O. Le Contel, P.-A. Lindqvist, C. T. Russell, & R. B. Torbert (2018), Intense electric fields and electron-scale substructure within magnetotail flux ropes as revealed by the Magnetospheric Multiscale mission, Geophys. Res. Lett., 45. https://doi.org/10.1029/2018GL079095

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Figure 1: Overview of the electron vortex. (a) Electron-scale perturbation to the magnetic field with a 1s running average removed as observed by the four MMS spacecraft. (b,c) Components of the electric field perpendicular to the magnetic field as observed by the four MMS spacecraft. (d,e) Components of the current perpendicular to the magnetic field based on the curl of the magnetic field (black), moments of the ion and electron distribution functions (blue), and assuming the current is driven by electrons drifting in the electric and magnetic fields (red). (f)  Diagram of the electron vortex encountered inside of one of the flux ropes. The observed profiles of the electric field and current are consistent with the indicated trajectories through the structure.