MIST

Magnetosphere, Ionosphere and Solar-Terrestrial

Latest news

Petition to eliminate harassment and bullying

MIST council is committed to fostering an open and inclusive scientific environment.

Many people will have seen the recent reports of bullying and harassment in Universities are becoming more and more widespread. In one of many steps to highlight the need for these actions to stop, an open letter and petition has been prepared by members of the wider community, including faculty from Imperial, UCL, and other UK and international institutions. This cross-institute example underlines the importance of eliminating harassment and bullying from the university and research environments. If you wish to sign the petition, you can find it by clicking here.

Our community is a big part of the RAS, which has a Code of Conduct and a Diversity, Equality and Inclusion Policy that we must adhere to:

  1. Promoting an inclusive environment for all.
    2. Promoting equality of opportunity.
    3. Welcoming applications from all backgrounds.
    4. Supporting and developing careers for all.
    5. Recruiting and promoting staff based on merit, rather than absence or presence of underrepresented characteristics.

We would strongly encourage our community to continue to participate in eradicating these issues from our scientific and every day lives.

MIST recognised in 2018 RAS awards

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

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

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

More details are available at the RAS website.

New MIST councillors in 2017

Congratulations to Jasmine Sandhu and Jonny Rae, both at MSSL, who have been elected (and, in Jonny’s case, re-elected) to MIST Council. They join Ian McCrea (Chair - RAL), Sarah Badman (Lancaster), Luke Barnard (Reading) and John Coxon (Southampton), all of whom continue in their posts.

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Rishbeth Prizes 2017

Congratulations to Jade Reidy (University of Southampton) and Mervyn Freeman (British Antarctic Survey) for winning this year's Rishbeth prizes for their presentations at the National Astronomy Meeting at the University of Hull this July.

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Nigel Wade

Nigel Wade
Nigel Wade - University of Leicester

It is with deep sadness that we have to inform the MIST community of the untimely death after a short illness of Nigel Wade who worked in the Radio and Space Plasma Physics (RSPP) group at Leicester for over 30 years.

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The Role of Proton Cyclotron Resonance as a Dissipation Mechanism in Solar Wind Turbulence

By Lloyd Woodham, Mullard Space Science Laboratory, University College London, UK

The solar wind contains turbulent fluctuations that are part of a continual cascade of energy from large scales down to smaller scales. At ion-kinetic scales, some of this energy is dissipated, resulting in a steepening in the spectrum of magnetic field fluctuations and heating of the ion velocity distributions, however, the specific mechanisms are still poorly understood. Understanding these mechanisms in the collisionless solar wind plasma is a major outstanding problem in the field of heliophysics research.

We use magnetic field and ion moment data from the MFI and SWE instruments on-board the Wind spacecraft to study the nature of solar wind turbulence at ion-kinetic scales. We analyse the spectral properties of magnetic field fluctuations between 0.1 and 5.5 Hz over 2012 using an automated routine, computing high-resolution 92 s power and magnetic helicity spectra. To ensure the spectral features are physical, we make the first in-flight measurement of the MFI ‘noise-floor’ using tail-lobe crossings of the Earth's magnetosphere during early 2004. We utilise Taylor's hypothesis to Doppler-shift into the spacecraft frequency frame, finding that the spectral break observed at these frequencies is best associated with the proton-cyclotron resonance scale, 1/kc, compared to the proton inertial length di and proton gyroscale ρi. This agreement is strongest when we consider periods where βi,perp ~ 1, and is consistent with a spectral break at di for βi,par « 1 and ρi for βi,perp » 1.

Histograms for 2012 of the estimated helicity onset frequency, fb, versus the three characteristic plasma scales, converted into frequencies using Taylor's hypothesis - fL represents fkc, fdi, and fρi, for each column respectively. The data used are for periods where 0.95 ≥ βi,perp ≥ 1.05. The colour-bar represents the column-normalised number of spectra. The black dashed lines represent fb = fL and similarly, the red dashed lines are fb = fL√2 and fb = fL√2, which give the resolution of the wavelet transform about the line fb = fL due to the finite width of the Morlet wavelet in frequency space. We see the best agreement between fb and fkc during these periods.

We also find that the coherent magnetic helicity signature observed at these frequencies is bounded at low frequencies by 1/kc and its absolute value reaches a maximum at ρi. These results hold in both slow and fast wind streams, but with a better correlation in the more Alfvénic fast wind where the helicity signature is strongest. We conclude that these findings are consistent with proton-cyclotron resonance as an important mechanism for dissipation of turbulent energy in the solar wind, occurring at least half the time in our selected interval. However, we do not rule out additional mechanisms.

Woodham et al., 2018, The Role of Proton Cyclotron Resonance as a Dissipation Mechanism in Solar Wind Turbulence: A Statistical Study at Ion-kinetic Scales, ApJ, 856, 49, DOI: 10.3847/1538-4357/aab03d