Tomography-like Approach for Analysing Colour Auroral Images

We report the first attempt to use tomography-like reconstructions tool with colour auroral imag- es. A colour camera imaging system (DAISY) was designed for studying the altitude profiles of the auro- ra, but the wide-band colour image data have not been tested for tomography-like analysis before. DAISY campaign measurements provide a large number of simultaneous auroral images with clear skies and aurora at two stations. We used images with simple, well-defined auroral structures and clear maximum in the emission intensity to examine whether images without narrow-band optical filters can be used for tomographic reconstructions. Our results suggest that the green line emission, which is the strongest auroral emission at λ = 557.7 nm, can be well-reconstructed with meaningful peak emission altitudes and horizontal scales even from the wide-band colour images. Fainter emissions at red (λ = 630.0 nm) and blue (λ = 427.8 nm) wavelengths could not be sufficiently separated from the dominant green spectral line due to the properties of the colour matrix of the CCD.

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