The Protonics project: distributed observations of auroral dayside Doppler-shifted hydrogen emissions

• Published in: Journal of Optical Technology
• Main Author: Holmes, Jeffrey Morgan
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: 2014
• Subjects: Canada; Greenland; Longyearbyen; Ny-Ålesund; Svalbard; Ny Ålesund
• Online Access: http://hdl.handle.net/10852/41051; http://urn.nb.no/URN:NBN:no-45651

The Protonics project is an effort to further understand the spatio-temporal dynamics of dayside auroral hydrogen emissions, also known as dayside proton aurorae. Spectrometers measuring dayside Balmer α (H α ) and Balmer β (H β ) were deployed to two locations on Svalbard at Longyearbyen and Ny-Ålesund. Measured hydrogen Doppler profiles were analysed via a Monte Carlo model of proton precipitation, resulting in an estimate of characteristic energy of the precipitating proton/hydrogen population. The difference in energy found between the two stations is interpreted as an ionospheric signature of magnetic merging near the magnetopause. Initially, a significant energy difference was discovered in two cases. However, weak emissions required spectral scans from the two instruments to be separately averaged for roughly two hours to produce the result. A third case featuring a stronger proton precipitation event was found, resulting in a statistically significant difference in energy with averaging on the order of minutes. This third case is the first statistically significant ground-based detection of the ion velocity filter effect in the dayside hydrogen aurora. A natural extension of the project was to investigate the relative occurrence of electron and proton aurora under the influence of solar wind shocks across the boreal auroral zone. Since this study required areal data coverage much larger than the vicinity of Svalbard, data from meridian scanning photometers (MSP) in Canada, Greenland and Svalbard were combined and compared with large-scale UV auroral images from the Polar spacecraft. Analysis of MSP data for events previously studied solely using space-based imagery added needed spatio-temporal resolution. Shock aurora propagation times were refined, and agreed with previous results to within uncertainties. Furthermore, the majority of instruments detected low energy discrete auroral arcs poleward of diffuse, higher energy proton and electron aurora. Two-pulse proton aurora onset sequences were also observed. A significant amount of time and effort was spent to ensure that the ground-based instruments had correct wavelength and intensity calibrations; the methodology for calibrating with respect to both is discussed in detail. Finally, the growing importance of inexpensive, commercially available digital single lens reflex cameras was recognized, and a detailed scheme for intensity calibration of the individual colours of a camera’s detector is described. Such instruments have proven quite useful as auroral context instruments and cloud detectors, thereby reducing time and effort required for data reduction.