Space Environment Physics group, Physics & Astronomy

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The aurora is a result of energised charged particles (electrons and protons) travelling down the Earth's magnetic field lines and colliding with the neutral atmosphere. These collisions ionise and excite the constituent atoms and molecules of the upper atmosphere, which can have important implications for the chemistry and climate of the region. The production of NOx and HOx by energetic particle precipitation has been shown to cause substantial changes in ozone concentration in the middle atmosphere. The electric currents associated with the aurora can also cause heating of the ionosphere and neutral atmosphere. The Space Environment Physics group in Southampton has recently developed a technique to measure the neutral temperature at 3 different altitudes simultaneously using aurora and airglow emissions observed by an advanced spectrograph located in the high Arctic. This PhD project has 3 main aims: 1) to further develop this new technique so that it can be automatically applied with no human input while still producing reliable results; 2) to design a prototype instrument with the specific function of measuring the neutral temperature in the upper atmosphere, using the new technique; 3) to study how the neutral temperature responds to different auroral processes and different "space weather" conditions.Methodology: This project will use two state-of-the-art optical instruments ("ASK" and "HiTIES") situated on Svalbard, in the high Arctic. HiTIES (High Throughput Imaging Echelle Spectrograph) is an advanced spectrograph which can record spectra at high resolution (0.1 nm) in multiple non-contiguous wavelength regions, using custom mosaic filters supplied by HORIBA UK Ltd., our industrial partner. A newly developed technique uses HiTIES observations to measure the neutral temperature simultaneously at 3 altitudes in the ionosphere. During this project, the new technique will be combined with an algorithm for automatically calibrating the spectra, and several "quality control" steps will be automated, so that the technique can be reliably applied with no human input (aim 1). A new instrument will be designed specifically for measuring ionospheric neutral temperature, in collaboration with our industrial partner (aim 2). ASK (Auroral Structure and Kinetics) consists of three highly-sensitive cameras. In combination with an ionospheric model, the ASK observations allow the energy and flux of auroral electron precipitation to be imaged, which makes an extremely powerful tool for understanding the physics of dynamic, fine-scale auroral structure. Simultaneous ASK and HiTIES observations will be used to study how specific properties of the aurora affect the neutral temperature (aim 3).