MIST

Magnetosphere, Ionosphere and Solar-Terrestrial

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MIST is the community of Magnetosphere, Ionosphere and Solar-Terrestrial researchers working in the United Kingdom. We represent the interests of MIST scientists and hold meetings to showcase MIST science twice a year.

  • News: News relevant to members of the MIST community.
  • Science: MIST science nuggets, as well as briefing papers designed to introduce policymakers to our research.
  • Meetings: Details of upcoming MIST meetings and summer schools, as well as the list of past MIST meetings.
  • Community: Find out about MIST researchers through the UK, MIST Council, MIST's mailing list, as well as the MIST Charter and history of the organisation.
  • Awards: The awards that MIST researchers are eligible for, alongside a list of those who have been honoured.

Plasma vorticity in the high-latitude ionosphere

By Gareth Chisham (British Antarctic Survey)

Measurements of ionospheric plasma flow vorticity can be used for studying ionospheric plasma transport processes, such as convection and turbulence, over a wide range of spatial scales. This study presents an analysis of probability density functions (PDFs) of ionospheric vorticity for selected regions of the northern hemisphere high-latitude ionosphere as measured by the Super Dual Auroral Radar Network (SuperDARN) over a 6-year interval (2000-2005 inclusive). Making certain assumptions, the observed asymmetric vorticity PDFs can be decomposed into two separate components: (1) A single-sided function that results from the large-scale vorticity inherent in the ionospheric convection pattern, driven by magnetic reconnection; (2) A symmetric double-sided function that results from meso-scale vorticity that derives from fluid processes such as turbulence, and from measurement uncertainties.

Figure with three vertical panels. This figure demonstrates the decomposition of the probability density function (PDF) of ionospheric vorticity into its large-scale and meso-scale components. The data is from 73-77 degrees AACGM latitude and 0800-1100 MLT (dawn convection cell), for IMF By positive conditions, for the years 2000-2006 inclusive. (a) PDF of all the measured vorticity measurements; (b) Separated components of the PDF with model fits; (c) Percentage contribution of each component for different values of vorticity.
This figure demonstrates the decomposition of the probability density function (PDF) of ionospheric vorticity into its large-scale and meso-scale components. The data is from 73-77 degrees AACGM latitude and 0800-1100 MLT (dawn convection cell), for IMF By positive conditions, for the years 2000-2006 inclusive. (a) PDF of all the measured vorticity measurements; (b) Separated components of the PDF with model fits; (c) Percentage contribution of each component for different values of vorticity.


Being able to model ionospheric vorticity in this way will help to improve models of ionospheric plasma flow that are often used in larger-scale system models. At the present time, these plasma flow models typically only consider the larger-scale convection flow. Our observation of a significant meso-scale flow vorticity component due to turbulence will have implications for the fidelity of these models.

See paper for further details: Chisham, G. and Freeman, M. P. (2023). Separating contributions to plasma vorticity in the high-latitude ionosphere from large-scale convection and meso-scale turbulence. Journal of Geophysical Research: Space Physics, 128, e2023JA031885, https://doi.org/10.1029/2023JA031885.

Related articles: Nuggets

MIST PhD Studentships

This resource is a collation of PhD student adverts from the MIST Community.

Please note that the list is not exhaustive and is not intended to be an accurate capture of all studentships in the MIST community.

Please feel welcome to share and distribute this resource to any interested parties. Potential PhD applications should direct all enquiries about individual adverts to the named contact.

If you have any suggestions on how we can improve this resource, you can contact us as This email address is being protected from spambots. You need JavaScript enabled to view it..

 

Find the list of MIST PhD Studentships here. 

Submit an advert here.

Related articles: PhD Studentships

Detection of the northern infrared aurora at Uranus using the W.M. Keck II Telescope and NIRSPEC instrument

By Emma Thomas (University of Leicester)

Three decades of searching for the infrared aurorae finally come to a successful conclusion as portions of the northern (IAU southern) aurorae have been confirmed at Uranus. The icy planet represents an enigma within our solar system, with the first and only visit by Voyager II in 1986, it remains one of the least documented planets in our solar system. This is exceptionally apparent with the planet’s history of auroral observations, where the UV aurorae have been observed a handful of times but no infrared (IR) counterpart has been confirmed, despite both aurorae appearing at Jupiter and Saturn. Analysis of IR aurorae at both Jupiter and Saturn have challenged what we know about magnetosphere-ionosphere coupling, highlighting a need for IR analysis at Uranus to uncover its mysteries. Since 2020 our team has meticulously analysed archived data of Uranus during 2006 from the Keck II telescope on Mauna Kea in Hawai’i. The timing of these observations was key, close to equinox, as it provided an optimal view of the predicted locations of the northern and southern aurorae. By examining the emission lines from these aurorae (the emitting ion being H3+) between 3.94 to 4.01 μm, we carried out a full spectrum best fit across 5 fundamental lines for each spatial pixel across the planet’s disk. By comparing these lines at specific locations, we were able to identify an average 88% increase in column ion densities with no significant temperature changes localised close to or at expected auroral locations for the northern aurora. With this confirmation at Uranus, we look forward to a new age of auroral investigations at both ice giant planets.

Measured H3+ Q(1,0-) intensity mapped across the upper atmosphere of Uranus against Uranian latitude and arbitrary longitude, (b) Total H3+ Emission calculated from the temperature and column density (explained in detailed in the Methods), (c) Estimated temperatures of the H3+ emissions from all five Q-branch lines and (d) Estimated column densities of H3+ emissions from all five Q-branch. The latitude is planetocentric whereas the longitude is arbitrary due to the loss of the Uranian Longitude System (ULS) since Voyager II. The solid black lines mark out the boundaries of E1 (on the left) and E2 (on the right). Within the boundaries, the Enhanced regions are unshaded, the Dim regions are shaded with dots, and the Intermediate regions are shaded with diagonal lines. Latitudes and/or longitudes that were not recorded during the observations have been greyed out.

References:

Thomas, E.M., Melin, H., Stallard, T.S. et al. Detection of the infrared aurora at Uranus with Keck-NIRSPEC. Nat Astron (2023). https://doi.org/10.1038/s41550-023-02096-5

Related articles: Nuggets