Quantitative analysis of multi-monochromatic observations of rapid small scale aurora

Abstract

This thesis presents analyses of flickering aurora observed using the state-of-theart Auroral Structure and Kinetics (ASK) multi-monochromatic ground-based auroral imager. Flickering aurora is observed as rapid (typically 2–20 Hz) oscillations in auroral luminosity. There are several competing theories for the generation mechanism of flickering aurora, although all use electromagnetic ion cyclotron (EMIC) waves. The work presented in this thesis has shown that precipitating electrons producing flickering aurora are accelerated by Landau damping of the EMIC wave, and that the wave parallel phase velocity is the primary factor limiting the electron precipitation energy. In addition, evidence is presented supporting the theory that very small structures in flickering aurora are caused by interference between multiple EMIC waves. A combined electron transport and ion chemistry model (the Southampton Ionospheric Model) has been used in this work to allow quantitative estimates of the energy of precipitating electrons responsible for aurora observed with ASK.

This thesis also presents a novel technique for intercalibrating optical and particle measurements of the aurora made by instruments onboard the Reimei satellite using the Southampton Ionospheric Model. This allows estimates of the flux of precipitating electrons at high energies above the detection limit of the Electron Spectrum Analyzer (ESA) particle detector. Optical images of the aurora obtained using the Multispectral Auroral Camera (MAC) instrument are also calibrated, allowing quantitative estimates of the auroral brightness without contamination from background light and auroral light reflected from the Earth. The technique has many possible applications in auroral studies using the Reimei satellite.

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Identifiers

ORCID for D.K. Whiter: orcid.org/0000-0001-7130-232X

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