Magnetosphere, Ionosphere and Solar-Terrestrial

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A Summary of the SWIMMR Kick-Off Meeting

The kick-off event for the Space Weather Innovation, Measurement, Modelling and Risk Study (one of the Wave 2 programmes of the UKRI Strategic Priorities Fund) took place in the Wolfson Library of the Royal Society on Tuesday November 26th. Seventy-five people attended the event, representing a range of academic institutions, as well as representatives from industry, government and public sector research establishments such as the UK Met Office. 

The morning session of the meeting consisted of five presentations, introducing the programme and its relevance to government, the Research Councils and the Met Office, as well as describing details of the potential calls. The presentations were as follows:

  •  Prof John Loughhead (Chief Scientific Advisor to BEIS) - Space Weather Innovation, Measurement, Modelling and Risk Programme (a governmental perspective). The slides from Prof John Loughhead's talk are available here.
  • Prof Chris Mutlow (Director of STFC RAL Space) - SWIMMR: Project funded by the Strategic Priorities Fund (a perspective from STFC).  The slides from Prof Chris Mutlow's talk are available here.
  • Jacky Wood (Head of Business Partnerships at NERC) - Space Weather Innovation, Measurement, Modelling and Risk (SWIMMR) - A NERC perspective.  The slides from Jacky Wood's talk are available here.
  • Dr. Ian McCrea (Senior Programme Manager for SWIMMR) -  SWIMMR: Space Weather Innovation, Measurement, Modelling and Risk: A wave 2 programme of the UKRI Strategic Priorities Fund.  The slides from Dr Ian McCrea's talk are available here.
  • Mark Gibbs (Head of Space Weather at the UK Met Office) - SWIMMR (Met Office perspective and detailed description of the calls.  The slides from Mark Gibb's talk are available here.

During the lunch break, the Announcement of Opportunity for the five NERC SWIMMR calls was issued on the NERC web site.  The afternoon therefore began with a brief introduction by Jacky Wood to the NERC Announcement of Opportunity, and the particular terms and conditions which it contained.

The remainder of the afternoon session was spent in a Question and Answer session in which attendees were able to ask questions to the speakers about the nature of the programme and the potential timing of future calls, and finally to an informal discussion session, in which participants gathered into groups to discuss the opportunities for funding which had been outlined. 

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.

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!

Exploring Key Characteristics in Saturn’s Infrared Auroral Emissions Using VLT-CRIRES: H3+ Intensities, Ion Line-of-Sight Velocities, and Rotational Temperatures

by Nahid Chowdhury (University of Leicester)

Saturn’s aurorae are generated by interactions between high-energy charged particles and neutral atoms in the upper atmosphere. Infrared observations of auroral emissions make use of H3+ – a dominant hydrogen ion in Saturn’s ionosphere – that acts as a tracer of energy injected into the ionosphere.

We analysed observations taken in May 2013 of Saturn’s northern infrared auroral emissions with the Very Large Telescope in Chile using the CRIRES instrument. The use of adaptive optics, combined with the high spectral resolution of VLT-CRIRES (100,000), meant that this dataset offered an unprecedented spatially and spectrally resolved ground-based view of Saturn's infrared aurora. Using discrete H3+ emission lines, we derived dawn-to-dusk auroral emission intensity, ion line-of-sight velocity, and thermospheric temperature profiles, allowing us to probe the physical properties of Saturn’s polar atmosphere.

Our analysis showed an enhancement in the dawn-side auroral emission intensity, a common feature that is known to be linked with solar-wind compressions in the kronian magnetosphere, and the presence of a localised dark region in the aurora very close to the pole. The ion line-of-sight velocity profile revealed previously unknown smaller-scale structures in the ion flows. In particular, the ion flows near the centre of the pole (at position B in Figure 1) could be consistent with the behaviour of a relatively small ionospheric polar vortex whereby the ions are interrupting the general dawn-to-dusk trend in movement to instead adopt a very sharp shearing motion of ions first toward midnight and then almost immediately back toward noon. Our thermospheric temperature derivations also reveal a very subtle temperature gradient that increases from 350 K on the dawn-side of the pole to 389 K on the dusk-side.

This work has bought to light complex features in the behaviour of H3+ ions in Saturn’s upper atmosphere for the first time and highlights the need for additional analyses of two-dimensional scanned maps of Saturn’s auroral regions with a view to addressing some of the major outstanding questions surrounding Saturn’s thermosphere-ionosphere-magnetosphere interaction.

For more information, please see the paper below:

Chowdhury, M. N., Stallard, T. S., Melin, H., & Johnson, R. E. ( 2019). Exploring key characteristics in Saturn's infrared auroral emissions using VLT‐CRIRES: H3+intensities, ion line‐of‐sight velocities, and rotational temperatures. Geophysical Research Letters, 46. https://doi.org/10.1029/2019GL083250.

 Plot showing the ion line-of-sight velocities and emission intensity as a function of colatitude.

Figure 1: The ion line-of-sight velocity and auroral emission intensity profiles are plotted as a function of co-latitude on the planet. Evidence for ion flows possibly consistent with the behaviour of an intriguing ionospheric polar vortex is adjacent to the area marked by the letter B, between approximately 0⁰ and 5⁰ co-latitude on the dawn-side of Saturn’s northern pole.

Directed network of substorms using SuperMAG ground-based magnetometer data

by Lauren Orr (University of Warwick)

Space weather can cause large-scale currents in the ionosphere which generate disturbances of magnetic fields on the ground. These are observed by >100 magnetometer stations on the ground. Network analysis can extract the important information from these many observations and present it as a few key parameters that indicate how severe the ground impact will be. We quantify the spatio-temporal evolution of the substorm ionospheric current system utilizing the SuperMAG 100+ magnetometers, constructing dynamical directed networks from this data for the first time. 

Networks are a common analysis tool in societal data, where people are linked based on various social relationships. Other examples of networks include the world wide web, where websites are connected via hyperlinks, or maps where places are linked via roads. We have constructed networks from the magnetometer observations of substorms, where magnetometers are linked if there is significant correlation between the observations. If the canonical cross-correlation (CCC) between vector magnetic field perturbations observed at two magnetometer stations exceeds a threshold, they form a network connection. The time lag at which CCC is maximal, |τC|, determines the direction of propagation or expansion of the structure captured by the network connection. If spatial correlation reflects ionospheric current patterns, network properties can test different models for the evolving substorm current system.

In this study, we select 86 isolated substorms based on nightside ground station coverage. The results are shown for both a single event and for all substorms in the figure. We find, and obtain the timings for, a consistent picture in which the classic substorm current wedge (SCW) forms, quantifying both formation and expansion. A current system is seen pre-midnight following the SCW westward expansion. Later, there is a weaker signal of eastward expansion.  Finally, there is evidence of substorm-enhanced magnetospheric convection. These results demonstrate the capabilities of network analysis to understand magnetospheric dynamics and provide new insight into how the SCW develops and evolves during substorms.

For more information please see the paper below:

Orr, L.,  Chapman, S. C., and  Gjerloev, J. W.. ( 2019),  Directed network of substorms using SuperMAG ground‐based magnetometer data. Geophys. Res. Lett.,  46. https://doi.org/10.1029/2019GL082824

 Plots showing the number of connections as a function of normalised time, for different polar regions.

Figure: The normalized number of connections, α(t',τC), is binned by the lag of maximal canonical cross-correlation, |τC|. Each panel stacks, one above the other, α(t',τC) versus normalized time, t’, for |τC|≤15. The regions are indicated on the polar plot and the regions were determined using Polar VIS images of the auroral bulge at the time of maximum expansion. Region B (around onset) exhibits a rapid increase in correlation following substorm onset.

Long-term variations in solar wind parameters, magnetopause location, and geomagnetic activity over the last five solar cycles

by Andrey Samsonov (Mullard Space Science Laboratory, UCL)

The magnetopause is a natural boundary between the solar wind and magnetospheric plasmas. Geosynchronous orbit, where numerous communications, meteorological and GPS satellites operate, is usually located in the magnetosphere but occasionally due to variable solar wind conditions the magnetosphere may significantly compress and those satellites will cross the magnetopause and get in direct contact with the solar wind plasma. Fast streams of dense solar wind plasma as well as solar energetic particles might damage the satellites. Therefore the study of variations of the magnetopause standoff distance is an important problem of space physics.  The magnetopause location can be described by empirical models (e.g. Shue et al., 1998; Lin et al., 2010).

In our recent work, we studied long term changes in the magnetopause position. We use both OMNI solar wind observations and empirical magnetopause models to reconstruct time series of the magnetopause standoff distance for nearly five solar cycles (from 1966 to 2018). The magnetopause standoff distance on this time scale depends mostly on the solar wind dynamic pressure (Pdyn). The 11-year solar cycles in the Pdyn variations are superimposed by an increasing trend before 1991 and a decreasing trend between 1991 and 2009. Correspondingly, we find that the standoff distance predicted by magnetopause models increases by nearly 2 Rfrom 1991 to 2009. The annual sunspot number (SSN), IMF magnitude and magnetospheric geomagnetic activity indices display the same trends as the dynamic pressure. We calculate extreme solar wind parameters and magnetopause standoff distance in each year using daily values and find that both extremely small and large standoff distances during a solar cycle preferably occur at solar maximum rather than at solar minimum (see figure below).

Furthermore, we calculated correlations between annual average solar wind and magnetospheric parameters, and the SSN. The annual IMF magnitude well correlates with SSN with a zero time lag, while the annual Pdyn correlates reasonably well with the SSN but with 3-years time lag. Both the annual solar wind density and velocity well correlate with the dynamic pressure, but the correlation coefficient is higher for density than for velocity. The annual Kp index better correlates with Pdyn, while Dst index better correlates with Bs (negative IMF Bz). This correlation analysis helps to better understand relations between solar, solar wind and magnetospheric parameters on the long time scale.

The knowledge of predicted magnetopause position for the next solar cycle is important for future space missions, especially for those which are intended to observe the dayside magnetopause whether in situ or remotely. One of the forthcoming missions which will study variations of the dayside magnetopause is the Solar Wind Magnetosphere Ionosphere Link Explorer (SMILE).

For more information, please see the paper below:

Samsonov, A. A., Bogdanova, Y. V., Branduardi‐Raymont, G., Safrankova, J., Nemecek, Z., & Park, J.‐S. ( 2019). Long‐term variations in solar wind parameters, magnetopause location, and geomagnetic activity over the last five solar cycles. Journal of Geophysical Research: Space Physics, 124. https://doi.org/10.1029/2018JA026355

Figure: The sunspot numbers, average and extreme IMF magnitude and Bz, IMF cone angle (the angle between IMF vector and xaxis), solar wind dynamic pressure and velocity, magnetopause standoff distance (solid lines for Shue et al.'s model and dashed lines for Lin et al.'s model), and geomagnetic Dst index. Annual average values shown by black, daily maximal and minimal values for each year shown by red and blue. Vertical lines separate solar cycles as indicated by numbers at the top.

Origin of the extended Mars radar blackout of September 2017

By Beatriz Sánchez-Cano (University of Leicester)

Several instrument operations, as well as communication systems with rovers at the surface, depend on radio signals that propagate throughout the atmosphere of Mars. This is the case for two radars currently operational in Mars’ orbit, sounding the ionosphere, surface and subsurface of the planet: The Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS) on board Mars Express, which operates between 0.1 and 5.5 MHz, and the Shallow Radar (SHARAD) onboard the Mars Reconnaissance Orbiter, which operates at 20 MHz. However, both radars typically suffer from complete blackouts for several days (and even weeks) when solar storms hit Mars. It is thought that an increase in the electron density of the lower ionosphere below 100 km occurs, where even a small enhancement in ionization significantly increases the signal attenuation. In analogy with Earth, some works suggest that solar protons of tens of MeV can cause these absorption layers. However, at Mars, the current origin andlong duration is not known.

Sánchez-Cano et al. (2019) focused on both the MARSIS and SHARAD radar performances during a powerful solar storm that hit Mars in September 2017. The space weather event consisted of a X8.2-class flare emitted by the Active Region 12673 at the western limb of the solar disk on 10 September 2017 (Figure 1a). This was followed by solar energetic particles (ions and electrons) that arrived at Mars few hours later, as recorded by the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission (see Figure 1b,c). Based on MAVEN observations and numerical simulations of energetic electron precipitation, Sánchez-Cano et al. (2019) found that high energy electrons (and not protons) were the main ionization source, creating a dense layer of ions and electrons of magnitude ~1010 m-3 at ~90 km on the Martian nightside. For frequencies between 3 and 20 MHz, the peak absorption level is found at 70 km altitude, and the layer was composed mainly of O2+, the main Martian ionosphere component. This layer attenuated radar signals continuously for 10 days, preventing the radars from receiving any HF signals from the planetary surface across a planetary scale (Figure 1d). This contrasts with the typical few hour durations that these phenomena have at Earth.

This work highlights the need for careful assessments of radar performances for future operational systems, especially during space weather events. During these events, a good characterization of the low ionosphere is necessary for radar operations (and other instruments that use HF radio links), operational planning, as well as for communications with the Martian surface in the HF range.

For more information please see the paper below:

Sánchez‐Cano, B., Blelly, P.‐L., Lester, M., Witasse, O., Cartacci, M., Orosei, R., et al ( 2019). Origin of the extended Mars radar blackout of September 2017. Journal of Geophysical Research: Space Physics, 124. https://doi.org/10.1029/2018JA026403

Figure 1: (a) MAVEN-EUV irradiance observations of wavelength 0.1-7 nm. (b) MAVEN-SEP ion differential flux spectra. (c) MAVEN-SEP electron differential flux spectra. (d) Each symbol denotes when MARSIS and SHARAD were in operation. Empty symbols designate the cases when the surface was observed, and filled symbols when was not observed. The exception are green diamonds that indicate the times when SHARAD observed a highly blurry surface.


Equatorial magnetosonic waves observed by Cluster satellites: The Chirikov resonance overlap criterion

by Homayon Aryan (University of Sheffield)

Numerical codes modelling the evolution of the radiation belts often account for wave-particle interaction with magnetosonic waves. The diffusion coefficients incorporated in these codes are generally estimated based on the results of statistical surveys of the occurrence and amplitude of these waves. These statistical models assume that the spectrum of the magnetosonic waves can be considered as continuous in frequency space, however, this assumption can only be valid if the discrete nature of the waves satisfy the Chirikov resonance overlap criterion.

The Chirikov resonance overlap criteria describes how a particle trajectory can move between two resonances in a chaotic and unpredictable manner when the resonances overlap, such that it is not associated with one particular resonance [Chirikov, 1960]. It can be shown that the Chirikov resonance overlap criterion is fulfilled if the following equation is satisfied:

δθ = (vl / tanθm) / (1 - (ω2/ce2))

where θm is the mean angle between the propagation direction and the external magnetic field, δθ is the standard deviation of the wave propagation angles , l is the harmonic number, v=me/mp is the electron to proton mass ratio, and Ωce is the electron gyro-frequency [Artemyev et al., 2015].

Here we use Cluster observations of magnetosonic wave events to determine whether the discrete nature of the waves always satisfy the Chirikov resonance overlap criterion, extending a case study by Walker et al. [2015]. An example of a magnetosonic  wave event is shown in panels a-c of the Figure. Panel d shows that the Chirikov overlap criterion is satisfied for this case. However, a statistical analysis shows that most, but not all, discrete magnetosonic emissions satisfy the Chirikov overlap criterion. Therefore, the use of the continuous spectrum, assumed in wave models, may not always be justified. We also find that not all magnetosonic wave events are confined very close to the magnetic equator as it is widely assumed. Approximately 75% of wave events were observed outside 3° and some at much higher latitudes ~21° away from the magnetic equator. This observation is consistent with some past studies that suggested the existence of low-amplitude magnetosonic waves at high latitudes. The results highlight that the assumption of a continuous frequency spectrum could produce erroneous results in numerical modelling of the radiation belts.

For more information please see the paper below:

Aryan, H., Walker, S. N., Balikhin, M. A., & Yearby, K. H. ( 2019). Equatorial magnetosonic waves observed by Cluster satellites: The Chirikov resonance overlap criterion. Journal of Geophysical Research: Space Physics, 124. https://doi.org/10.1029/2019JA026680

Figure: Observation of a magnetosonic wave event measured by Cluster 2 on 16 November 2006 at around 02:08 to 02:33~UT. The top three panels (a, b, and c) show the dynamic wave spectrogram (Bx, By, and Bz respectively) measured by STAFF search coil magnetometer. Panel d shows the analysis of the Chirikov resonance overlap criterion outlined in equation shown on top-left of the panel. The blue and red dots represent 10~s averaged values of dqand the ratio on the right hand side of equation respectively.