MIST

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!

On the Calculation of the Effective Polytropic Index in Space Plasmas

by Georgios Nicolaou (MSSL, UCL)

The effective polytropic index of space plasmas γ is crucial for understanding the dynamics of the plasma particles. For instance, numerous theoretical descriptions and simulations of plasmas, demand the knowledge of the effective polytropic index for accurate calculations.  

Several studies, determined γ within different plasma regions, using single spacecraft observations of the plasma density and temperature T. The effective polytropic index γ is typically determined from a linear chi-squared minimization fitting of lnT as a function of lnn.

In this paper, we investigate the accuracy of γ calculations based on the standard fitting analysis, considering plasma n and T measurements with a certain level of uncertainty σn and σT respectively (see Figure 1). We model typical plasmas, and we show that uncertainty in the plasma density measurements introduces a systematic error in the calculation of γ, and potentially leads to artificial isothermal indices (Figure 1, left). On the other hand, uncertainty in the plasma temperature measurements introduces a statistical error in the calculation of γ (Figure 1, right). We analyze Wind spacecraft observations of solar wind protons in order to investigate the propagated uncertainties in real plasma applications, confirming our model predictions (Figure 1).

These results highlight how uncertainties in plasma measurements can lead to erroneous values of the poytropic index. In this study we present a new data-analysis approach for reducing the number of erroneous data-points from future analyses.

Plots showing how the polytropic index varies with uncertainty in density and uncertainty in temperature.

Figure 1. Normalized histograms of (left) γ as a function of σn/n, for σT/T < 15% and (right) γ as a function of σT/T, for σn/n < 1%. The white line is the mean value of the histogram in each column. We display only the range of uncertainties for which we have more than 100 data points. On each panel, we show the predictions of our model (red) for plasma parameters corresponding to the mode values of each parameter for the analyzed intervals.

For more information, please see the paper:

Nicolaou, G., G. Livadiotis, R. T. Wicks (2019). On the Calculation of the Effective Polytropic Index in Space Plasmas. Entropy, 21, 997. https://doi.org/10.3390/e21100997.

Long-term Correlations of Polytropic Indices with Kappa Distributions in Solar Wind Plasma near 1 AU

by Georgios Nicolaou (MSSL, UCL)

The polytropic process determines a relationship between the plasma density and temperature, during the transition of the plasma from one equilibrium state to another under constant specific heat. This process is described by the effective polytropic index, which can be determined by the analysis of plasma density and temperature measurements, and is a crucial parameter in determining the dynamics of the plasma.

Over the last few decades numerous studies have shown that the velocities of the plasma particles often follow kappa distribution functions. The kappa index that labels and governs these distributions also becomes a key parameter to understand the plasma dynamics.

Interestingly, recent studies have shown that the polytropic indices and kappa indices of space plasmas are related, in the presence of potential energy. Moreover, the relationship between the two indices defines the potential degrees of freedom.

This is the first statistical study to analyze Wind spacecraft observations to derive the polytropic index and the kappa index of solar wind protons and investigate their relationship, over the last two solar cycles. We show that, most of the time, the two indices are related, exactly as predicted by the theory. When able, we quantify the relation in order to derive the potential degrees of freedom. Among others, we show that an enhanced solar activity and/or interplanetary magnetic field, reduces the potential degrees of freedom, and decrease the dimensionality of a typical electric field potential from dr = 3 in solar minimum, to dr = 2 in solar maximum (Figure 1).

Overall, these results identify fundamental properties of the solar wind plasma, that demonstrate clear dependences on solar cycle.

Dimensionality plotted as a function of sunspot number.

Figure 1. Dimensionality dr for a typical interplanetary potential as a function of sunspot number Sn. The linear fit to data points (black dash) is also shown. The results indicate that the potential dimensionality dr reduces with increasing Sn.

For more information, please see the paper:

Nicolaou G. and G. Livadiotis (2019). Long-term correlations of polytropic indices with Kappa distributions in solar wind plasma near 1 AU. The Astrophysical Journal, 884:52, https://iopscience.iop.org/article/10.3847/1538-4357/ab31ad/meta 

The Variation of Geomagnetic Storm Duration with Intensity

By Carl Haines (University of Reading)

Variability in the near-Earth solar wind conditions can adversely affect a number of ground- and space-based technologies.  Some of these space weather impacts on ground infrastructure are expected to increase primarily with geomagnetic storm intensity, but also storm duration, through time-integrated effects. Forecasting storm duration is also necessary for scheduling the resumption of safe operating of affected infrastructure. It is therefore important to understand the degree to which storm intensity and duration are related.

In this study, we use the recently recalibrated aa index, aaH, which provides a global measure of the level of geomagnetic disturbance. We analyse the relationship between geomagnetic storm intensity and storm duration over the past 150 years, further adding to our understanding of the climatology of geomagnetic activity. In particular, we construct and test a simple probabilistic forecast of storm duration based on storm intensity. Using a peak-above-threshold approach to define storms, we observe that more intense storms do indeed last longer but with a non-linear relationship (See Figure 1a).

A plot showing the duration increases with storm intensity and the number of storms decreases with storm intensity.A plot showing the observed probability and the model output, both as a function of storm intensity. The distributions are very similar.

Figure 1 (a) The mean duration (red) and number of storms (blue) plotted as a function of storm intensity. (b) The probability that a storm will last at least 24 hours plotted as a function of storm intensity. The black line shows the observed probability and the red line shows the model output.

Next, we analysed the distribution of storm durations in different intensity classes. We found them to be approximately lognormal, with parameters depending on the storm intensity. On this basis we created a method to probabilistically predict storm duration given peak intensity. Equations are given to find lognormal parameters as a function of storm peak intensity. From these, a distribution of duration can be created and hence a probabilistic estimate of the duration of this storm is available. This can be used to predict the probability a storm will last at least e.g. 24 hours. Figure 1b shows the output of the model for a range of storm peak intensity compared against a test set of the aaH index. The model has good agreement with the observations and provides a robust method for estimating geomagnetic storm duration. The results demonstrate significant advancements in not only understanding the properties and structure of storms, but also how we can predict and forecast these dynamic and hazardous events.

For more information, please see the paper:

Haines, C., Owens, M.J., Barnard, L. et al. Sol Phys (2019) 294: 154. https://doi.org/10.1007/s11207-019-1546-z 

Cassini’s Grand Finale:- Planetary Period Oscillations are everywhere and the dayside field ‘lags’

by Gabby Provan (University of Leicester) 

Saturn’s Planetary Period Oscillations are oscillations at close to Saturn’s planetary period which have been observed to organize all of Saturn’s ionospheric and magnetospheric parameters throughout the Cassini mission.  There are two oscillatory systems, one in the Northern hemisphere and one in the Southern. The enduring mystery is that so far we have yet to understand how a perfectly axisymmetric planetary magnetic field can create such oscillations

In this paper, we study the magnetic field throughout the Cassini Grand Finale orbits.  On these orbits Cassini passed from the northern auroral region in the dawn sector, through the gap between the D ring inner edge and Saturn’s atmosphere, and outbound to the southern auroral region in the dusk sector (See Figure 1). We observe dual PPO modulations on auroral, subauroral, ring-region and intra-ring region field lines – in other words everywhere (see Figure 2).  This is the first time that PPOs have been observed on and inside ring region field lines.  The presence of such field perturbations may provide an explanation for apparent PPO-related phenomena observed in the ring material itself, through the action of these fields on charged dust grains (see e.g. Chancia et al., 2019).

A schematic showing Cassini's pass through key regions of interest.

Figure 1: Plot of the periapsis pass trajectories of the initial and final proximal orbits, Revs 271  (blue) and 292 (red), projected into a meridian plane in cylindrical coordinates.  The darker blue field-aligned area corresponds to field lines mapping through the main ring region in the equatorial plane, between the inner boundary of the C ring and the outer boundary of the A ring, while the lighter blue field-aligned area corresponds to field lines mapping through the D ring.

Next, we considered the residual magnetic field, having discounted the magnetic signature of the PPOs and Saturn’s ring current from the observed magnetic field observations.  We found that the residual azimuthal field had a lagging configuration in the subauroral region with a magnitude ~3-5 nT.  These fields extend essentially unmodified inwards, crossing the ring region and the field lines mapping to Saturn synchronous orbit, to the outer boundary of D ring field lines.  The lagging field indicates a field-aligned current flow of ~0.25 MA rad-1 flowing from the southern ionosphere toward the C and inner B rings. The physical origin of the extended region of lagging dayside fields remains unclear. 

Magnetic field data.

Figure 2: Field data from all the proximal orbit periapsis passes, color-coded  according the northern PPO system phase.  The data are plotted versus time from their field-parallel points taken as t = 0 (central vertical black dotted line), over the interval between -100 and +80 min,  Vertical dashed lines indicate the equatorward boundary of the auroral region.   The green solid lines mark the field line passing through the outer boundary of the A ring, while the green dashed and dotted lines mark the field lines passing through the outer and inner boundaries of the D ring, respectively.  Data in Figures 2a-2c on the left are color-coded by northern PPO phase such that phases near 0°-360° are colored red and phases near 180° blue.  Similarly, data in Figures 2d-2f on the right are color-coded by northern PPO phase such that phases near 90° are colored red and phases near 270° blue.

For more information, please see the paper:

Provan, G.,  Cowley, S. W. H.,  Bradley, T. J.,  Bunce, E. J.,  Hunt, G. J.,  Cao, H., &  Dougherty, M. K. ( 2019). Magnetic field observations on Cassini's proximal periapsis passes: Planetary period oscillations and mean residual fields. Journal of Geophysical Research: Space Physics,  124. https://doi.org/10.1029/2019JA026800

 

Effects of VLF transmitter waves on the inner belt and slot region

by Johnathan Ross (British Antarctic Survey)

Signals from man made VLF (Very Low Frequency) transmitters can leak from the Earth-ionosphere wave guide into the inner magnetosphere, where they propagate as electromagnetic waves and contribute to electron dynamics in the inner radiation belt and slot region. These waves are highly localised around the transmitters and are strongest on the nightside. It has been suggested that these waves may be responsible for removing the hazardous MeV energy electrons from this region that can be extremely damaging to satellites. The VLF transmitter waves scatter electrons in pitch angle (the angle between the background field and electron velocity). In an average sense, this scattering can be represented by a diffusion equation, with a diffusion coefficient that can be calculated using quasi-linear theory. In this study we use ~5 years of Van Allen Probesobservations to construct global statistical models of the diffusion coefficients for each individual VLF transmitter, as a function of L*, Magnetic Local Time (MLT) and geographic longitude.

These diffusion coefficients are then incorporated into a 1D pitch-angle diffusion model with longitude and MLT dependence. We find that global averages of the wave power capture the long-term dynamics of the loss process, despite the highly localised nature of the waves in space. We use our model to assess the role of VLF transmitter waves compared to other important loss processes (hiss waves and coulomb collisions) on electron loss in the inner radiation belt and slot region. The figure shows the decay timescales as a function of L value for different combinations of the VLF transmitter (T), coulomb collisions (C), and hiss wave (H) processes. At moderate relativistic energies, E~500 keV (panel d), waves from VLF transmitters have a significant role! They reduce electron lifetimes by an order of magnitude or more, down to the order of 200 days near the outer edge of the inner radiation belt. However, VLF transmitter waves are ineffective at removing multi-MeV electrons (panel f) from either the inner radiation belt or slot region. The results suggest that although the VLF transmitters are important for radiation belt loss, they cannot be responsible for removing the dangerously high energy electrons from the region occupied by satellites.

For more information, please see the paper:

Ross, J. P. J.,  Meredith, N. P.,  Glauert, S. A.,  Horne, R. B., &  Clilverd, M. A. ( 2019).  Effects of VLF transmitter waves on the inner belt and slot region. Journal of Geophysical Research: Space Physics,  124, 5260– 5277. https://doi.org/10.1029/2019JA026716

Electron decay timescales considering a combination of different loss processes.

Figure: Electron decay timescales from the 1D model with MLT and longitude averaging. The lines correspond to: black - Coulomb collisions; green - hiss and Coulomb collisions; blue - VLF transmitters and Coulomb collisions; red - VLF transmitters, hiss and Coulomb collisions.