Filamentary structure in the upper atmosphere
Lead Research Organisation:
University of Southampton
Department Name: Sch 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, seen regularly at high latitudes such as northern Scandinavia, but rarely at the latitudes of the UK. We use the aurora as a diagnostic to find out many things about the environment around the Earth, mainly in the region of upper atmosphere called the ionosphere. That environment is made up of 'plasma' (ionised gas) often called the fourth state of matter, which makes up over 95% of the directly observable material in the cosmos. Yet it is strangely difficult to maintain and study within Earth's biosphere. The upper atmosphere provides an ideal natural laboratory for its study since there is no need to consider collisions of the plasma with container walls. 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. We are interested in understanding the smallest scale auroral structures, and how the energy changes within them influence the large scale environment. 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 was 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 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 will combine these optical measurements with measurements from special radar experiments, which are designed to use a technique known as interferometry to measure structures smaller than the beam width, and with accuracy of position and height better than has been possible to date. The radar imaging technology is new in the field of incoherent scattering radar and will be one of the cornerstones of a future project that is called EISCAT_3D. The technology employed is Aperture Synthesis Imaging Radar (ASIR). It is very similar to the technology used by radio astronomers (VLBI, Very Long Baseline Interferometry) to image stellar objects, and also has some similarity with the SAR (Synthetic Aperture Radar) technique used onboard airplanes and satellites to map the Earth's surface and other planetary surfaces. In the radio astronomy case the source itself spontaneously emits radiation that is collected by a number of passive antennas. In ASIR, the radar transmitter acts like a camera flash to illuminate the target (the ionosphere or atmosphere) and a number of antennas collect the scattered radiation exactly as in the radio astronomy case (or like the lens of a camera). From this point on, the two cases are essentially identical. To construct the image of the target, the cross-correlation between the signals is calculated from all different pairs of receivers. By using the radar imaging technique we will become the pioneers of this new technique in Europe.
People |
ORCID iD |
Betty Lanchester (Principal Investigator) |
Publications
Archer J
(2011)
Dynamics and characteristics of black aurora as observed by high-resolution ground-based imagers and radar
in International Journal of Remote Sensing
Dahlgren H
(2011)
Energy and flux variations across thin auroral arcs
in Annales Geophysicae
Dahlgren H
(2015)
Coexisting structures from high- and low-energy precipitation in fine-scale aurora
in Geophysical Research Letters
Dreyer J
(2021)
Characteristics of fragmented aurora-like emissions (FAEs) observed on Svalbard
in Annales Geophysicae
Grydeland T
(2011)
Orthogonal-polarization multipulse sequences
in Radio Science
Gustavsson B
(2010)
Rise and fall of electron temperatures: Ohmic heating of ionospheric electrons from underdense HF radio wave pumping
in Journal of Geophysical Research: Space Physics
Kataoka R
(2021)
Small-Scale Dynamic Aurora.
in Space science reviews
Keiling, Andreas; Donovan, Eric; Bagenal, Fran; Karlsson, Tom
(2012)
Auroral Phenomenology and Magnetospheric Processes: Earth and Other Planets
Lanchester B
(2011)
Separating and quantifying ionospheric responses to proton and electron precipitation over Svalbard SEPARATING PROTON AND ELECTRON RESPONSES
in Journal of Geophysical Research: Space Physics
Lanchester B
(2017)
Some remaining mysteries in the aurora
in Astronomy & Geophysics
Lanchester Betty
(2017)
Some remaining mysteries in the aurora
in ASTRONOMY & GEOPHYSICS
Pedersen T
(2010)
Creation of artificial ionospheric layers using high-power HF waves
in Geophysical Research Letters
Reidy J
(2018)
Interhemispheric Survey of Polar Cap Aurora
in Journal of Geophysical Research: Space Physics
Reidy J
(2017)
Multi-instrument observation of simultaneous polar cap auroras on open and closed magnetic field lines
in Journal of Geophysical Research: Space Physics
Spry J
(2014)
Modelling N21P contamination in auroral O+ emissions
in Journal of Atmospheric and Solar-Terrestrial Physics
Tuttle S
(2014)
Temporal and spatial evolution of auroral electron energy spectra in a region surrounding the magnetic zenith
in Journal of Geophysical Research: Space Physics
Tuttle S
(2014)
Calculating the auroral electron energy
in Astronomy & Geophysics
Tuttle S
(2020)
Horizontal electric fields from flow of auroral O<sup>+</sup>(<sup>2</sup>P) ions at sub-second temporal resolution
in Annales Geophysicae
Whiter D
(2021)
Fine-scale dynamics of fragmented aurora-like emissions
in Annales Geophysicae
Whiter D
(2014)
RELATIVE BRIGHTNESS OF THE O + ( 2 D - 2 P ) DOUBLETS IN LOW-ENERGY AURORAE
in The Astrophysical Journal
Whiter D
(2010)
Using multispectral optical observations to identify the acceleration mechanism responsible for flickering aurora
in Journal of Geophysical Research: Space Physics
Whiter D
(2021)
Fine Scale Dynamics of Fragmented Aurora-Like Emission
Description | 1) We have used state-of-the-art multi-wavelength imaging with radar data to quantify the energy distribution in aurora at the highest possible temporal and spatial resolution. The optical instrument is a unique combination of three cameras which give information about the different emissions in the aurora. For example, emissions from nitrogen molecules are caused by high energy precipitation, while emissions from oxygen atoms result from low energy particles. Such emissions can be used in sophisticated models to give detailed energy distributions within narrow filaments making up the aurora. The results have been used to determine the acceleration processes responsible for several different auroral features, such as high temporal flickering, and splitting arcs. 2) We have used emissions from the long-lived oxygen ion (O+) to measure plasma flows in and around auroral arcs and to test the hypothesis that the effects of small scale structure contribute to large scale circulation. We have done this work using a new 3 dimensional model. The resulting flows are compared with large scale measurements made with radars and found to be in agreement with the direction of the flows, but with much larger magnitudes, providing evidence for the underestimates in heating (through the action of electric fields) that are made if high resolution measurements are not used. 3) We have developed the interferometry capability through international collaborations at the EISCAT Svalbard Radar to test the competing theories for the generation of naturally enhanced ion-acoustic lines (NEIAL). The technique was found to work but the number of events was small during the grant period. This work continues through our collaborators. |
Exploitation Route | The most direct potential relevance to UK and international research work is the application of novel radar techniques, which have been applied in the project through international collaborations, using the EISCAT Svalbard Radar and interferometry (Aperture Synthesis Interferometry). This work is ongoing and the operation of the interferometry capability will be an important diagnostic for the development stage of EISCAT-3D, Europe's next-generation radar for the study of the high-latitude atmosphere and geospace located in northern Scandinavia. The other main product is the application of the modelling results to high resolution observations, to provide energy and flux of the aurora at the smallest scales. The grant has leveraged support from the Citizen Science Alliance to develop an "Aurora Zoo" which will use the interested public to continue the research into auroral energy distributions in small scale structures. |
Sectors | Education Environment |
URL | http://space.soton.ac.uk/ |
Description | The aurora is a phenomenon that draws much interest from the general public and makes an excellent teaching aid about simple physical processes. Therefore under this grant we used seed funding to develop a prototype "Aurora Zoo" using summer students from Physics and Electronics and Computer Science. As a result, we took the idea forward to the Citizen Science Alliance, applying for funding to develop a full version of the Zoo for the general public. This application was successful, and led to further support in a subsequent grant, such that the Aurora Zoo is scheduled to go live in 2019. |
First Year Of Impact | 2012 |
Sector | Education,Environment,Other |
Impact Types | Cultural Societal Policy & public services |
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 |
Description | Gave the James Dungey Lecture at the Royal Astronomical Society |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | No |
Geographic Reach | National |
Primary Audience | Public/other audiences |
Results and Impact | The James Dungey Lecture is a named lecture that is open to the general public interested in Astronomy and Geophysics. The topic is chosen to give a general view of the research field, and questions are taken at the end, with the lecture being written up for publication in Astronomy and Geophysics and also reported in the Observatory. Most questions were particular to the research area, but several questions arose after the lecture from members of the public who were keen to further their knowledge. |
Year(s) Of Engagement Activity | 2017 |
Description | Talk at Winchester Science Centre (INTECH) |
Form Of Engagement Activity | A talk or presentation |
Part Of Official Scheme? | Yes |
Geographic Reach | Regional |
Primary Audience | Public/other audiences |
Results and Impact | 170 members of public attended (and paid to attend). Lively discussion afterwards. Many favorable emails and feedback after the event. Asked to return for another presentation |
Year(s) Of Engagement Activity | 2010 |
URL | http://www.winchestersciencecentre.org/ |