MIST

Magnetosphere, Ionosphere and Solar-Terrestrial

Latest news

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.

Rishbeth Prizes 2018

MIST Council would like to congratulate Joe Eggington and Rob Shore for winning the Rishbeth Prizes for best student talk and best poster respectively at the 2018 Spring MIST meeting held in Southampton.

Joe’s talk was on the topic of ‘Magnetosphere-ionosphere coupling in global MHD simulations’, and Rob’s poster posed the question ‘How directly driven are the polar ionospheric equivalent currents?’

As part of winning the prize, Joe and Rob have been invited to write articles for Astronomy & Geophysics – watch out for those in an upcoming issue!

MIST recognised in 2018 RAS awards

MIST Council would like to congratulate those who have been recognised for contributions to the field by the Royal Astronomical Society recently, but particularly we would like to congratulate those members of the MIST community who are to be honoured at the next National Astronomy Meeting.

Emma Bunce has won the Chapman Medal for outstanding contributions to the understanding of the magnetospheres of gas giants, Matt Taylor has won the Service Award for his exceptional work in co-ordinating and contributing to ESA's Rosetta mission, and Jim Wild has been awarded the James Dungey lectureship for his excellent and highly relevant work on substorms and reconnection in the magnetotail. We would also like to congratulate Kerri Donaldson Hanna for winning the Winton Award for planetary science.

MIST Council applauds each of the winners, alongside the other academics who will be recognised in Liverpool this spring!

More details are available at the RAS website.

Shapes of Electron Density Structures in The Dayside Mars Ionosphere

By Catherine Diéval, Department of Physics, Lancaster University, UK.

The dayside Mars ionosphere is thought to be reasonably well understood (see e.g. a review by Withers, 2009). The top of the ionosphere is influenced, among various factors, by localized crustal magnetic fields (e.g. Acuña et al., 1999), solar EUV and solar wind input, in the absence of a global magnetic moment. However a peculiar ionospheric feature is still the subject of ongoing research: non-horizontal electron density structures are regularly observed in localized areas with strong and near vertical crustal magnetic fields, in the topside ionospheric levels remotely sampled by the MARSIS radar (Picardi et al., 2004) onboard the Mars Express orbiter (e.g. Andrews et al. 2014; Diéval et al., 2015; Duru et al., 2006; Gurnett et al., 2005). These structures are detectable via oblique echoes returned to the radar after it sends a radio wave pulse through the ionosphere.The reflectors often appear at higher apparent altitude than the surrounding ionosphere, and so are nicknamed "bulges".

Previous studies also used radar returns uncorrected for signal dispersion. Actually, the group velocity of the radio waves varies with the refractive index of the plasma layers encountered, until reflection occurs. The apparent ranges of the received echoes are calculated using the time delays of the echoes and assuming the speed of light in vacuum. However this leads to overestimating the ranges,so interpretations on the shape of the structures based on these are uncertain.

Our work (Diéval et al., 2018), is a statistical study using timeseries of electron density profiles (electron density function of altitude, corrected for signal dispersion) to study the shape of 48 structures, in their full frequency (thus altitude) range, during the period that Mars Express passes over them.

Figure 1 shows that at any frequency, the most frequent shape is the bulge, dwarfing three other types of detected shapes: dips, downhill slopes and uphill slopes. All these shapes are inclined, thus able to reflect oblique echoes. Interestingly, bulges were reproduced in simulation results of Matta et al. (2015).

For more information, see the paper below:

Diéval, C., Kopf, A. J., & Wild, J. A. (2018). Shapes of magnetically controlled electron density structures in the dayside Martian ionosphere. Journal of Geophysical Research: Space Physics, 123, 3919–3942. https://doi.org/10.1002/2017JA025140

Figure 1: Distribution of the four simplest shapes of structures as a function of frequency, for the 48 events, displayed as colored symbols: bulges (red dots), dips (black diamonds), uphill slopes (blue ‘x’), downhill slopes (green ‘+’). Data points at frequency levels within in the sensitivity gaps are not displayed.

Plasma Heating From Dipolarizations in Saturn's Magnetotail

By Andrew Smith, Department of Physics and Astronomy, University of Southampton, UK.

Magnetic reconnection in a planet's magnetotail allows the stretched field to snap back towards the planet, carrying with it a bundle of plasma.  This is known as a dipolarization front, which often manifest in spacecraft data as rapid rotations of the magnetic field accompanied by a change in the local plasma character.  Dipolarization fronts have been observed at Earth, Mercury, Jupiter and Saturn and are thought to be linked to bright auroral displays.

We performed a large automated survey of Cassini data, identifying 28 intervals when the spacecraft was in the path of dipolarization fronts sweeping towards Saturn.  The changes in plasma properties were investigated, along with the supra-thermal composition.  A large dawn-dusk asymmetry was present in the observations, with 79% of the events located post-midnight.  Figure 1 shows the change in plasma characteristics from that preceding the front (a) to within the dipolarizing material (b).  All of the identified events showed an increase in the electron temperature and a coupled reduction in the electron density.  Figures 1c and (d) show the relative change in temperature and density respectively.  Overall, the temperature was found to increase by factors between 4 and 12, while the density dropped by factors of 3-10.  The variable plasma properties are thought to be linked to a variable reconnection location, particularly post-midnight.

Figure 1: Panels (a) and (b) show the electron density plotted aainst the electron temperature for before (a) and after (b) the dipolarization front.  These panels are plotted on the same axes scale for direct comparison.  The gray lines indicate how the events move in density-temperature space.  Panels (c) and (d) show the electron temperature and density (respectively) before the front plotted against the electron temperature and density after the passage of the front.  The points and error bars provided are the mean and standard error of the mean respectively.  The diagonal black dashed line shows the location of $y = x$: where the points would lie if there was no change following the passage of the front.  The red dashed lines indicate least squares linear fits to the data; the details of the fit parameters are provided on the panels.  The color bar for all four panels indicates the radial distance at which the spacecraft encountered the event.

 

For more information, see the paper below:

Smith, A. W., Jackman, C. M., Thomsen, M. F., Sergis, N., Mitchell, D. G., & Roussos, E. (2018). Dipolarization fronts with associated energized electrons in Saturn's magnetotail. Journal of Geophysical Research: Space Physics, 123, 2714–2735. https://doi.org/10.1002/2017JA024904

The Association of High‐Latitude Dayside Aurora With NBZ Field‐Aligned Currents

By Jennifer Carter, Department of Physics and Astronomy, University of Leicester, UK

Under northward interplanetary magnetic field conditions, when the IMF Bz > 0 nT, non-filamentary auroral emissions may be seen within the dayside polar cap and separate from the main auroral oval. These emissions are associated with lobe reconnection occurring at the high-latitude magnetopause on open field lines. Two mechanisms have been proposed to explain these emissions. The first involves the precipitation of magnetosheath plasma at the footprint of the high-latitude reconnection site, resulting in a “cusp spot”. This cusp spot has been shown to move in response to the east-west (BY) orientation of the solar wind. The second mechanism associates the auroral emissions known as High-Latitude Detached Arcs (HiLDAs) with upward field-aligned currents inside the polar cap. Under northward IMF, twin-cell field-aligned currents (NBZ system) can be found inside of the main region 1-region 2 field aligned current system. Under the influence of positive IMF BY, the upward NBZ cell expands across the noon sector in the Northern Hemisphere, whereas under negative BY, the downward cell will enlarge. The reverse scenario occurs in the Southern Hemisphere for either BYdirection.

Previous observations of HiLDAs have been limited to the Northern Hemisphere for a small data set, and previous authors have linked this phenomenon to season, as the HiLDAs have only been detected during the summer. We used concurrent auroral observations from Defense Meteorological Satellite Program Special Sensor Ultraviolet Spectrographic Imager (SSUSI) experiment, and FAC distributions constructed from the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE), from the Iridium telecommunication satellite constellation, to perform a large statistical study of HiLDAs under varying IMF for both hemispheres. We observe a patch of auroral emission that is co-located with the upward NBZ FAC in the dayside polar cap in both the Northern and Southern Hemispheres under northward IMF conditions.

We observe the HiLDA emission to move in response to changes in the IMF BYcomponent (e.g. Figure 1), whereby the HiLDAs are seen to move into the polar cap under positive BY, or be pushed up against, and therefore indiscernible from, the main auroral oval under negative BY(Northern Hemisphere case). We also support the hypothesis that these emissions are only detectable in the summer hemisphere, indicating a dependence on ionospheric conductivity via photoionisation in the predominantly sunlit hemisphere.

For more information, see the paper below:

Carter, J. A., Milan, S. E., Fogg, A. R., Paxton, L. J., & Anderson, B. J. (2018). The association of high‐latitude dayside aurora with NBZ field‐aligned currents. Journal of Geophysical Research: Space Physics, 123. https://doi.org/10.1029/2017JA025082

Figure 1: Northern Hemisphere summer auroral emissions in the Lyman-Birge-Hopfield long band with overlaid field-aligned current contours, for the Northern (N, row a) and Southern (S, row b) Hemispheres. Clock angles are given in the left-hand column. Interplanetary magnetic field magnitudes are between 5 and 10 nT. Field-aligned current contours are overlaid for upward (red) and downward (turquoise) currents, at absolute magnitudes of 0.1 (solid line), 0.3 (dashed line), and 0.5 (dotted line) μA/m2.

 

Submit a new nugget

If you would like to submit a nugget, please contact This email address is being protected from spambots. You need JavaScript enabled to view it. and we will arrange a slot for you in the schedule. Nuggets should be 100–300 words long and include a figure. Please get in touch!

Solar Wind Dependence of Magnetospheric Ultra-Low Frequency Plasma Waves

By Sarah Bentley, Department of Meteorology, University of Reading, UK

Ultra-low frequency plasma waves (ULF, 1-15 mHz) are implicated in the energisation and transport of radiation belt electrons. Therefore a description of magnetospheric ULF wave power in terms of driving parameters is highly desirable for radiation belt forecasting; in particular, we want to describe power in terms of solar wind properties, as the solar wind is the dominant driver behind these waves.

However, identifying solar wind driving parameters is severely hampered by the nature of the solar wind. All solar wind parameters are highly interrelated due to their common solar sources and the interactions within the solar wind between the Sun and Earth, resulting in the effect that all solar wind properties correlate so strongly with speed vswthat investigating their relationship to magnetospheric properties is difficult.

To circumvent analysis techniques that require properties such as a linear interdependence between these parameters, we use a series of simple yet systematic two-parameter plots (e.g. Figure 1) to identify which parameters are causally correlated to ULF wave power, rather than just correlated via a relationship with speed vsw. We find that speed, the southward component of the interplanetary magnetic field and summed power in proton number density perturbations (vsw, Bz < 0 and δNp) are the three dominant parameters driving power in magnetospheric ultra-low frequency waves. These parameters can be used in future modelling but are also of interest because there is clearly a threshold at Bz = 0, and because ULF wave power depends more on perturbations δNp than the number density Np itself.

For more information, see the paper below or an informal blog post here.

Bentley, S. N., Watt, C. E. J., Owens, M. J., & Rae, I. J. (2018). ULF wave activity in the magnetosphere: Resolving solar wind interdependencies to identify driving mechanisms. Journal of Geophysical Research: Space Physics, 123. https://doi.org/10.1002/2017JA024740

Figure 1: A two-parameter plot taken from Bentley et al., 2018. We bin the ULF power observed at one station (roughly corresponding to geostationary orbit) at one frequency (2.5mHz) and observe whether it increases with increases in solar wind speed vswand/or the component Bz of the interplanetary magnetic field, using fifteen years of data. Cut-throughs at constant speed and Bz are shown in (b) and (c). ULF power increases with speed and with more strongly negative Bz for Bz<0, but only with speed for Bz>0.