Mr. James Waters
University of Southampton, UK
Multi-decadal observations of auroral kilometric radiation with the Wind spacecraft and its variability during substorms
Abstract : Auroral Kilometric Radiation (AKR) is circularly-polarised radio emission that originates from particle acceleration regions along magnetic field lines that coincide with discrete auroral arcs and geomagnetic activity. For decades, radio astronomy instruments aboard various spacecraft have been used to derive the source directions and flux densities of radio emissions of various origin. The Wind spacecraft has been in operation for 25 years and its flight characteristics (spin-stabilised, orthogonal antennae) have been considered in the development of techniques involving direction-finding and polarimetry of a radio source. Such techniques allow for the angular coordinates, the angular radius and the Stokes (flux and polarisation) parameters to be retrieved, and have been used previously to study solar radio emissions under assumptions of the source polarisation. Here, a technique that accounts for partial polarisation in an extended radio source is developed that will return source parameters for not only AKR but other sources, although there are limitations to the automation of the analysis that must be examined. With polarisation considered, the long timespan of Wind data can produce a utile dataset. Statistical properties of AKR can be examined, with the extent of local time sampling of Wind bolstering previous studies. The previously observed correlation between morphological changes in the source region and magnetospheric substorm onset can be studied further, and lists of substorm phase timings can be used to examine the general variability during these events.
Leave a Comment
Posted: 11th December 2019 by Simon Purser
2020-01-29, 15:00: Mr. J. Waters (University of Southampton)
Mr. James Waters
University of Southampton, UK
Multi-decadal observations of auroral kilometric radiation with the Wind spacecraft and its variability during substorms
Abstract : Auroral Kilometric Radiation (AKR) is circularly-polarised radio emission that originates from particle acceleration regions along magnetic field lines that coincide with discrete auroral arcs and geomagnetic activity. For decades, radio astronomy instruments aboard various spacecraft have been used to derive the source directions and flux densities of radio emissions of various origin. The Wind spacecraft has been in operation for 25 years and its flight characteristics (spin-stabilised, orthogonal antennae) have been considered in the development of techniques involving direction-finding and polarimetry of a radio source. Such techniques allow for the angular coordinates, the angular radius and the Stokes (flux and polarisation) parameters to be retrieved, and have been used previously to study solar radio emissions under assumptions of the source polarisation. Here, a technique that accounts for partial polarisation in an extended radio source is developed that will return source parameters for not only AKR but other sources, although there are limitations to the automation of the analysis that must be examined. With polarisation considered, the long timespan of Wind data can produce a utile dataset. Statistical properties of AKR can be examined, with the extent of local time sampling of Wind bolstering previous studies. The previously observed correlation between morphological changes in the source region and magnetospheric substorm onset can be studied further, and lists of substorm phase timings can be used to examine the general variability during these events.
Category: Future Seminars, Seminars, Uncategorised
Meet the Judges of our "Reach for the Stars" Astrophotography competition! Brenda Fitzsimons is photo editor of the @IrishTimes. To learn more about the competition and submit an entry see dias.ie/reachforthesta… #DIASdiscovers #astrophotography
Nice work 👏 twitter.com/dias_geophysic…
Following on from our post, highlighting inspiring #WomeninResearch and encouraging #MondayMotiviation to explore these subjects. @ChantalKobel presents Celticist, Nessa Ní Shéaghdha and her contributions to the discipline youtu.be/LGPLltjTBKw #DIASdiscovers
We have entered the last month to capture that amazing photo of the sky and win our Astrophotography competition. We are accepting photographs taken between 01 January 2020 and 31 March 2021. You can submit an entry up to Friday 02nd April 2021. More: dias.ie/reachforthesta…
Meet the Judges of our "Reach for the Stars" Astrophotography competition! @petertgallagher is Head of @DIASAstronomy & has spent the past two decades studying the Sun its impacts on the Earth. To learn more and submit an entry see dias.ie/reachforthesta… #DIASdiscovers
She has over 15 years’ experience working in PR and communications and has wide-ranging experience of providing strategic communications support to organisations. Learn more about the competition and submit an entry 👉dias.ie/reachforthesta… #DIASdiscovers #astrophotography
Meet the Judges of our "Reach for the Stars" Astrophotography competition! @MartinaPQuinn is the Founder & Managing Director of @helloalicepr.
Want to learn more about what's happening on Mars? Check out our public lecture from November delivered Dr John Clinton and titled MarsQuakes! (5/5) youtu.be/_Lp0oLJ8Ahs
And then this Thursday @NASAMars Perseverance rover reaches Mars, which will try to land in a near equatorial crater called Jezero. Here you can see a possible route around the crater. (4/5)