MIST

Magnetosphere, Ionosphere and Solar-Terrestrial

Latest news

UK Space Agency call for nominations for the position of Chair of the Science Programme Advisory Committee

The UK Space Agency (UKSA) is seeking a new Chair for the Science Programme Advisory Committee (SPAC). The position of Chair of the Science Programme Advisory Committee will become vacant on 1 July 2019.

The UK Space Agency welcomes applications from the UK space science community. The full position and person specifications are on the Government's website.

 

UKRI 2019 Opportunities Call

The Opportunities Call is designed to support the STFC PPAN community by providing funding for ‘pump-priming’ activities. The closing date is 13 June 2019, and proposals will be considered from any consortia or university groups eligible to apply for UKRI funding. For further details please visit the UKRI website.

This call considers ‘the PPAN community’ to encompass the following broad areas of STFC’s remit: particle physics, particle astrophysics, astronomy, nuclear physics, accelerator physics, solar and planetary science, and computing that underpins these areas.

The Opportunities Call supports pump-priming activities as opposed to substantive research programmes. Examples of pump-priming activities could include: networking; partnership building; workshop development and delivery; design studies; proofs of concept; or other pilot approaches.

In line with the call aims, pump-priming activities may be proposed for entirely new programmes of work, or to allow existing projects to move in new or interesting directions.

To enable the support of a portfolio of projects of varying scale, proposals to the Opportunities call will be aligned in two separate rank ordered lists: one for proposals of values up to £50k and another for proposals of value £51k–140k. Subject to the advice of the assessment process, STFC anticipates supporting approximately 15 projects in total as a result of the Opportunities Call.

Special Issue of Annales Geophysicae on “Satellite observations for space weather and geo-hazard”

We solicit research articles on the subject of “Satellite observations for space weather and geo-hazard” for a forthcoming Special Issue of Annales Geophysicae. This Special Issue is not a conference proceedings volume and is not limited to research presented at the EGU conference. All submissions must be original papers that meet the quality and peer-review standards of Annales Geophysicae. The deadline for manuscript submission is 31 August 2019 and the editors are M. Piersanti, L. Conti, X. Shen, and G. Balasis.

Measurements from LEO satellites can provide a global view of near-Earth electromagnetic, plasma and particle environments and are complementary to ground-based observations, which have limited spatial coverage. The AMPERE project and integration of the SWARM data into ESA’s Space Weather program are relevant examples of this approach. The availability of thermosphere and ionosphere data from the DEMETER satellite and the new operative CSES mission demonstrates that satellites that have not been specifically designed for space weather studies can also provide important contributions to this research field. On the other hand, there is evidence that earthquakes and artificial emitters can generate electromagnetic anomalies into the near-Earth space. A multi-instrumental approach, by using ground-based observations (magnetometers, magnetotelluric stations, ionospheric sounders, GNSS receivers, etc.) and LEO satellite (DEMETER, SWARM, CSES, the scheduled CSES-02 mission, etc.) measurements can help in clarifying the lithosphere–atmosphere–ionosphere coupling (LAIC) mechanisms due to electromagnetic emissions before, during and after large earthquakes as well as from thunderstorm activity.

 

STFC Public Engagement Early-Career Researcher (PEER) Forum

The STFC has issued a call for applications to join their Public Engagement Early-Career Researcher (PEER) Forum, which is designed to support talented scientists and engineers in the early stages of their career in developing their public engagement and outreach goals. This forum is geared towards PhD students and early-career postdocs developing ideas for public engagement with similarly-minded researchers in a context that allows them to feed suggestions for the improvement of STFC's programmes back to STFC itself, and involves meeting twice a year. The deadline for applications is 4pm on 3 June 2019. For more information and more detail on what the scheme involves, you can visit the PEER Forum webpage or This email address is being protected from spambots. You need JavaScript enabled to view it..

The aims of the PEER Forum are as follows:

  • To foster peer learning and peer support between early career scientists and engineers with a passion for public engagement and outreach.
  • To improve understanding of the support STFC provides for public engagement and outreach (including funding mechanisms, evaluation, and reporting) and how to successfully utilise this support.
  • To stimulate discussions that help to develop and influence STFC’s approaches to public engagement.

ESA Science Programme Committee greenlights SMILE

The Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) has been given the green light for implementation by ESA's Science Programme Committee. SMILE will explore the Sun-Earth connection in a very novel way, by mapping solar wind-magnetosphere interactions in soft X-rays. SMILE is a joint mission by ESA and the Chinese Academy of Sciences (CSA). The UK is one of many countries contributing to the payload development.

The SMILE payload comprises four instruments: a soft X-ray imager (SXI), a UV auroral imager (UVI) and an in situ measurement package composed of a light ion analyser and a magnetometer. The UK leads SXI, Canada leads UVI, and China leads the ion analyser and magnetometer. SMILE will fly in a highly elliptical polar orbit with an apogee of 20 Earth radii to image the magnetosphere and the Northern Lights for more than 40 hours continuously per orbit. The launch is planned in November 2023.

For more information, visit the European Space Agency, the Chinese Academy of Sciences, or Mullard Space Science Laboratory.

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.