MIST

Magnetosphere, Ionosphere and Solar-Terrestrial

Latest news

2019 RAS Council elections

As you may have seen, the nominations for RAS Council are currently open with a deadline of 29 November. MIST falls under the “G” (Geophysics) category and there are up to 3 councillor positions and one vice-president position available. MIST Council strongly encourages interested members of the MIST community to consider standing for election.
 
Clare Watt (University of Reading) has kindly volunteered to be a point of contact for the community for those who may wish to talk more about being on council and what it involves. Clare is a councillor on RAS Council, with her term due to complete in 2020, and This email address is being protected from spambots. You need JavaScript enabled to view it..
 

 

Outcome of SSAP priority project review

From the MIST mailing list:

We are writing to convey the outcome of this year’s priority project “light touch” review, specifically with reference to those projects within the remit of SSAP. We would like to thank all the PIs that originally submitted ideas, and those who provided updates to their projects over the summer. SSAP strongly believe that all the projects submitted are underpinned by strong scientific drivers in the SSAP area.

The “light touch” review was undertaken with a unified approach by SSAP and AAP, considering factors that have led to priority project development (in STFC or other research councils) or new funding for priority projects (1/51 projects in the STFC remit) in the last 12 months. After careful discussion, it was agreed by SSAP and AAP not to select any project where the remit clearly overlaps with UKSA (i.e. space missions or TRL 4+), reflecting STFC’s focus on ground-based observations, science exploitation and TRL 0-3 development. Whilst in no way reflecting the excellence of the science, or community scientific wishes, this approach has resulted in some changes to the list of SSAP priority projects. However, now, unlike at the time of the original call, it is clear that such projects cannot move forwards without UKSA (financial) support, and such funds are already committed according to UKSA’s existing programme. SSAP remain strongly supportive of mission-led science in solar-system exploration, so SSAP have strongly recommended that the high-level discussions between UKSA and STFC continue with a view to supporting a clear joint priority projects call in future, more naturally suited to mission and bi-lateral opportunities.

The priority projects (and PIs) identified by SSAP for 2019/20 are:

  • Solar Atmospheric Modelling Suite (Tony Arber)
  • LARES1: Laboratory Analysis for Research into Extra-terrestrial Samples (Monica Grady)
  • EST: European Solar Telescope (Sarah Matthews)

SSAP requested STFC continue to work with all three projects to expand their community reach and continue to develop the business cases for future (new) funding opportunities. In addition, SSAP have requested that STFC explore ways in which the concept of two projects—“ViCE: Virtual Centres of Excellence Programme / MSEMM Maximising Science Exploitation from Space Science Missions”—can be combined and, with community involvement, generate new funding for science exploitation and maximising scientific return in solar-system sciences. Initially this consultation will occur between SSAP and STFC.

We would like to thank the community again for its strong support, and rapid responses on very short timescales. A further “light touch” review will occur in 2020, with a new call for projects anticipated in 2021. SSAP continue to appreciate the unfamiliar approach a “call for proposals with no funding attached” causes to the community and are continuing to stress to STFC that the community would appreciate clearer guidance and longer timescales in future priority project calls.

Yours sincerely,

Dr Helen Fraser on behalf of SSAP

The Global Network for the Sustainability In Space (GNOSIS)

The Global Network for the Sustainability In Space (GNOSIS) is an STFC Network+ with the goal of helping researchers within the Particle, Nuclear and Astrophysics areas to engage with researchers from other research councils and industry to study the near Earth space environment. For more details, visit the GNOSIS website or see this issue of the GNOSIS newsletter.

Over the next few years we expect a large increase in the number of satellites in Earth orbit. This will lead to unprecedented levels of space traffic much of which will end as debris. The aim of this network is to understand the debris populations and its impact on space traffic management with a view to enabling a safer environment.

The free GNOSIS lunch event will be held on 18 November 2019 at the British Interplanetary Society at Vauxhall, London, with a video link to the Royal Observatory Edinburgh, to facilitate participation from across the UK. Tickets can be obtained here.

GNOSIS will be producing a programme of meetings for both space operations specialists and subject matter novices and will be able to support the development of collaborative ideas through project and part graduate student funding. Details of our first workshop will be announced in the next month.

If you are an academic with no direct experience but have knowledge of areas such as observations, data analysis, simulation or even law, then register your interest on our website. If you are a currently working in the space sector or if you are just interested in the aims and goals of the network please also register your interest and get involved.

SWIMMR: A £19.9M programme of the UKRI Strategic Priorities Fund

Space Weather Instrumentation, Measurement, Modelling and Risk (SWIMMR) is a £19.9M programme of the UK Research and Innovation (UKRI) Strategic Priorities Fund.

MIST would like draw the attention of the research community to the potential opportunities which will become available as a result of this programme, which received final approval from the Department for Business, Energy and Industrial Strategy (BEIS) in August. The programme will run from now until March 2023 and is aimed at improving the UK’s capabilities for space weather monitoring and prediction. UKRI’s Strategic Priorities Fund provides a means for linking research council investment to governmental research priorities, hence the areas being emphasised in the programme reflect space weather threats to critical infrastructure, as reflected in the UK national risk register.

The programme will be delivered jointly by the STFC and NERC, mainly through open grant calls, but including some elements of commissioned work to be delivered through open competitive tenders. The first calls are expected to appear during the coming weeks. More information about the programme is available through the RAL Space website, and is forthcoming from the NERC web site.

To mark the official launch of the programme and provide more details of the planned activities, a kick-off meeting is being held in the Wolfson Library of the Royal Society on Tuesday 26 November 2019, from 10:30. Pre-registration is required for this event and can be done using this link. We hope that many of you will be able to attend.

Representing the MIST Community in award nominations

MIST Council has recently launched an effort to create an award nominations task force with the following aims:

  1. Actively contribute towards more equal representation and a diverse range of nominees for awards
  2. Recognise and promote the work of overlooked members of the community
  3. Provide a means for students and ECRs to gain experience in preparing an effective nomination package

The initial plan is to start by considering those awards given out by the Royal Astronomical Society. This is so there will be sufficient time to prepare nomination packages by the RAS deadline (July 2020), and the wide range of awards will allow us to consider the entire MIST community. The task force is spearheaded by Oliver Allanson, Jasmine Sandhu, and Maria-Theresia Walach.

This task force is inspired by Liz MacDonald, a heliophysicist at NASA’s Goddard Space Flight Center. Liz Macdonald organized the Nomination Task Force within AGU’s Space Physics and Aeronomy (SPA) section, which has been summarised in an article in Eos. We plan to work in a manner similar to that described in the article, as we believe that by having a community task force we will be able to achieve community-wide representation in a timely manner.

If you would like to be part of the task force then please sign-up using our Google Form by Friday 4th October. At this stage we are not soliciting for specific ideas for nominees. Instead we are seeking to gauge support and receive feedback. We would like to emphasise that all members of the MIST community are welcome, and indeed encouraged, to sign-up to to join this task force, from PhD student to Emeritus Professor.

Nuggets of MIST science, summarising recent MIST papers in a bitesize format.

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/animation. Please get in touch!

What can the annual 10Be solar activity reconstructions tell us about historic space weather?

By Luke Barnard, Department of Meteorology, University of Reading, UK.

Cosmogenic isotopes, such as 10Be and 14C, provide estimates of past solar activity, constraining past space climate with reasonable uncertainty for several millennia. However, much less is known about past space weather because as we look further into the past, particularly before the space age, reliable records of space weather events become scarce (Barnard et al., 2017).

Advances in the analysis of 10Be by McCracken & Beer (2015) (MB15) suggest that annually resolved 10Be can be significantly affected by solar energetic particle (SEP) fluxes. This presents an opportunity to provide a valuable record of past SEP fluxes, and to determine and isolate any SEP effects for the accurate quantification of past solar activity.

In Barnard et al. (2018) we assess whether the MB15 reconstruction was biased by significant historic space weather, and whether 10Be can provide a proxy of such events. We compared the MB15 reconstruction of the annual heliospheric magnetic field magnitude (HMF) with two independent HMF estimates  derived from sunspot records and geomagnetic variability (Owens et al., 2016), which are thought to be unbiased by space weather events. Computing the differences between the MB15 HMF reconstruction with the geomagnetic and sunspot reconstructions over the 115-year period of 1868-1983, we performed statistical tests to infer whether the differences appear to depend on large space weather events. We use records of ground level enhancements (GLEs) and great geomagnetic storms (GGMS, the top 10% of all storms identified in the aa geomagnetic index), as markers of years with large space weather events.

Figure 1 shows the empirical cumulative distribution function (ECDF) of the differences between the MB15 and geomagnetic reconstructions (Fg1), and between MB15 and the sunspot reconstruction (Fr1). Panels A and C show the ECDF of Fg1 (red line) in years with and without GGMS respectively, while Panels B and D show the ECDF of Fr1 (blue line) under the same conditions. Each panel also shows bootstrapped estimates of the ECDF (grey lines) from resampling the complete Fg1 and Fr1 series, independent of whether GGMS occurred. The distributions of Fg1 and Fr1 are different in years with and without GGMS, and, being at the opposite extremes of the bootstrap distribution, are larger than would be expected due to random sampling of the same underlying distribution. Consequently, we interpret this as evidence that large space weather events do bias the MB15 reconstruction.

Future advances rely on reducing uncertainty on the inversion of the cosmogenic isotope data, requiring a holistic modelling approach for the Earth system, magnetosphere, heliosphere and local interstellar environment. The research output of the MIST community is important in improving the models underlying the inversion of the cosmogenic isotope data, and consequently for improving the quantification of past space weather and climate.

Please see the paper below for more information:

Barnard, L., McCracken, K. G., Owens, M. J., & Lockwood, M. (2018). What can the annual 10Be solar activity reconstructions tell us about historic space weather? J. Space Weather Space Clim., 8, A23. DOI: 10.1051/swsc/2018014

Figure 1. (A) The ECDF of Fg1is given in red, computed for only years without GGMS events. The grey lines show 100 bootstrap estimates of the Fg1ECDF, computed by randomly sampling the Fg1series. Panel B has the same structure as panel A, but instead shows the ECDF of Fr1in blue. Panels (C) and (D) have the same structure as (A) and (B), but instead show the ECDFs of Fg1and Fr1for only years with GGMS events.

Field‐Aligned Currents in Saturn's Magnetosphere: Observations From the F‐Ring Orbits

By Gregory J. Hunt, Department of Physics, Imperial College London, UK.

In a magnetized planetary system, large-scale electrical currents that flow along the magnetic field lines are fundamental in the transfer of angular momentum through the coupling of the magnetosphere and ionosphere [e.g., Cowley, 2000]. In the case of Saturn, two such types of these current systems have been deduced from Cassini magnetometer data and studied in detail [e.g. Bunce et al., 2008; Talboys et al., 2009a; Talboys et al., 2009b; Southwood & Kivelson, 2009; Talboys et al., 2011; Hunt et al., 2014, 2015, 2016; Bradley et al., 2018]. The first type is an axisymmetric, quasi-static field-aligned current system, which is associated with the transfer of angular momentum from the planet to Saturn’s outer magnetospheric plasma. The second type is associated with the planetary period oscillation (PPO) phenomenon at Saturn [e.g., Carbary & Mitchell, 2013]. Specifically, there are two rotating field-aligned current systems with oppositely directed currents on either side of the pole. One is associated with the northern hemisphere and the other with the southern hemisphere. These two rotating current systems result in the near 10.7-hour oscillations observed throughout the Saturnian system [e.g., Southwood & Kivelson, 2007; Andrews et al., 2010; Southwood & Cowley, 2014].

Hunt et al. [2018a] performed a statistical survey for both the northern and southern hemisphere auroral field-aligned current regions from a set of orbits prior to Cassini’s Grand Finale, known as the F-ring orbits. This analysis showed in each hemisphere there was the quasi-static and that hemisphere’s PPO field aligned current systems. Interestingly, the PPO current systems’ strengths had decreased by approximately 50% when compared to previous results [Hunt et al., 2014, 2015]. This reduction is in agreement with a decrease in the PPO amplitudes as determined by Hunt et al. [2018b]. The general form and strengths of the overall current profiles for both hemispheres are shown in the figure below. Other differences were observed in the azimuthal field poleward and equatorward of the field-aligned current region. These imply possible seasonal and local time effects on the overall field-aligned current structure and azimuthal field topology.

For more information, see our paper below:

Hunt, G. J., Provan, G., Bunce, E. J., Cowley, S. W. H., Dougherty, M. K., & Southwood, D. J. (2018a). Field‐aligned currents in Saturn's magnetosphere: Observations from the F‐ring orbits. Journal of Geophysical Research: Space Physics, 123, 3806–3821. https://doi.org/10.1029/2017JA025067

Figure: Overall current profiles versus northern (a) and southern (b) ionospheric colatitudes. Coloured profiles are the F-ring orbit data, with color code shown at the top of the figure. A mean profile is shown by the joined filled circles. (c, d) Comparison between the F-ring orbit mean profiles from (a) and (b) and the 2008 mean profile (joined crosses) for the northern and southern hemisphere, respectively. The error bars are the standard deviation of the F-ring means. Grey shaded regions are standard deviation of the 2008 means. Black squares show colatitude bins where Welch’s T test shows the 2008 and F-ring averages are significantly different. The open-closed field line boundary (OCB) is shown by the vertical dashed lines.

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.