Visiting Researchers in Space Environment Physics

Lead Research Organisation: University of Southampton
Department Name: School of Physics and Astronomy

Abstract

The subject of our study is the aurora borealis, or northern lights, which is an amazing natural lightshow in the sky. We use the aurora as a diagnostic to find out many things about the space environment around the Earth. That environment is made up of 'plasma' (ionised gas) which makes up over 95% of the directly observable material in the cosmos, yet is strangely difficult to maintain and study within Earth's biosphere. Aurora appears to be a ubiquitous property of magnetised planets and its detection from planets beyond our solar system would give us a uniquely detailed view of their magnetic field and atmosphere. The story of the aurora begins at the Sun, which is a continuous but very variable energy source, in the form of a plasma stream (the 'solar wind') which impacts on the Earth. Auroral displays are regularly seen at high latitudes, such as northern Scandinavia, and only rarely at the latitudes of the UK. To study the aurora, we use a special instrument which has three cameras looking at different 'colours' simultaneously. The proposed research is for studies of very dynamic and structured aurora at the highest possible resolution. The instrument is named ASK for Auroral Structure and Kinetics. It is designed to measure a small circle of 3 degrees in the 'magnetic zenith' i.e. straight up along the Earth's magnetic field. Particles from the Sun spiral along these imaginary magnetic field lines, and lose energy when they collide with atmospheric oxygen and nitrogen. The exact colour (or wavelength of the light) depends on how much energy the incoming particle started with, and on what molecule or atom it hits. The ASK cameras help to unravel this complicated process by making very precise measurements in space and time of three emissions which have different physical origins. We also use measurements from radars and other optical instruments to give more information about the aurora. We do our research in Svalbard, which is so far north that it is dark all day in the winter months, ideal for optical measurements. It is not fully understood how the particles obtain so much energy when they are caught up in Earth's magnetic field. Many questions about the aurora have been answered since the space age from rockets and satellites flying through auroral events. However, the central question remains: how particles are accelerated inside the Earth's magnetic field, and how they make such complex and dynamic patterns in the atmosphere. There are a great many theories of auroral particle acceleration that have varying degrees of success in explaining auroral behaviour; however, none to date has credibly explained how auroral arcs can be so thin and dynamic. The plasma in the upper atmosphere is the closest large-scale plasma to us and hence using radars and optical instruments allows us to exploit this natural plasma laboratory. There are many examples of phenomena that were discovered by studying the plasma around the Earth that have been applied in fusion research, solar physics and astrophysics. We aim to continue this process. In recent years it has become clear that if a person was lost in space, the first signal of Earth he or she could detect would be a radio emission generated by the same accelerated particles that produce the aurora. This is called AKR (Auroral Kilometric Radiation). Because aurora and AKR is produced by all the magnetised planets in our solar system we envisage a time when space-based radio detectors (possibly on the Moon) and exceptionally large, multi-segment telescopes will be used to detect and analyse planets around other stars. A long-term goal of our research is to develop ways that this could be achieved.

Publications

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Dahlgren H (2009) First direct optical observations of plasma flows using afterglow of in discrete aurora in Journal of Atmospheric and Solar-Terrestrial Physics

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Dahlgren H (2010) Simultaneous observations of small multi-scale structures in an auroral arc in Journal of Atmospheric and Solar-Terrestrial Physics

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Frey H (2010) Small and meso-scale properties of a substorm onset auroral arc SMALL-SCALE AURORA STRUCTURES in Journal of Geophysical Research: Space Physics

 
Description This grant funded visiting researchers with expertise in modelling of the plasma environment in which fine scale aurora occurs. As a result we were able to use real data as input to theoretical models to help understand the way that particles are accelerated to cause energy to be dissipated in the auroral filaments we observe.
Exploitation Route Our data from optical instruments with unparalleled resolution can be used by theoreticians.
Sectors Education,Environment

 
Description NERC Standard grant
Amount £474,660 (GBP)
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 10/2010 
End 09/2013
 
Description Auroral Structure and Kinetics (ASK) 
Organisation Royal Institute of Technology
Department Department of Space and Plasma Physics
Country Sweden 
Sector Academic/University 
PI Contribution Shared expenses for the running of the instruments (tapes, travel, cables, optics) Shared running experiments in Svalbard, and maintaining the large data base
Collaborator Contribution Shared expenses for the running of the instruments (tapes, travel, cables, optics) Shared running experiments in Svalbard, and maintaining the large data base
Impact Award of International Fellowship between KTH and Southampton (Dr H. Dahlgren)
 
Description EISCAT Svalbard Radar Aperture Synthesis Imaging (EASI) 
Organisation Royal Institute of Technology
Department Department of Space and Plasma Physics
Country Sweden 
Sector Academic/University 
PI Contribution Radar hours awarded and shared between the three groups. Personnel sent to Svalbard to help with installation of antennas.
Collaborator Contribution Construction and supply of the interferometry antennas. Development of the software for experiment and analysis of results.
Impact PhD project (Goodbody) completing 2013
Start Year 2009
 
Description EISCAT Svalbard Radar Aperture Synthesis Imaging (EASI) 
Organisation University of Tromso
Department Department of Physics
Country Norway 
Sector Academic/University 
PI Contribution Radar hours awarded and shared between the three groups. Personnel sent to Svalbard to help with installation of antennas.
Collaborator Contribution Construction and supply of the interferometry antennas. Development of the software for experiment and analysis of results.
Impact PhD project (Goodbody) completing 2013
Start Year 2009
 
Description International Postdoctoral Award 
Organisation Royal Institute of Technology
Department Department of Space and Plasma Physics
Country Sweden 
Sector Academic/University 
PI Contribution Postdoctoral fellowship held at Southampton, but funded by Swedish Research Council. Research collaborations involve supervision and use of data from shared instruments. Postdoctoral researcher has facilities supplied for her work: space, computing support and other University amenities
Collaborator Contribution Postdoctoral fellowship held at Southampton, but funded by Swedish Research Council.
Impact Just begun.
Start Year 2013