HR: 0800h
AN: SM51B-1304    [Abstracts]
TI: Fine Structure Withing Auroral Flicker
AU: Holmes, G J
EM: gholmes@phys.ucalgary.ca
AF: University of Calgary, Department of Physics and Astronomy, 2500 University Drive NW, Calgary, AB T2N 1N4 Canada
AU: * Trondsen, T S
EM: trondsen@phys.ucalgary.ca
AF: University of Calgary, Department of Physics and Astronomy, 2500 University Drive NW, Calgary, AB T2N 1N4 Canada
AU: Knudsen, D J
EM: knudsen@phys.ucalgary.ca
AF: University of Calgary, Department of Physics and Astronomy, 2500 University Drive NW, Calgary, AB T2N 1N4 Canada
AU: Cogger, L L
EM: lcogger@phys.ucalgary.ca
AF: University of Calgary, Department of Physics and Astronomy, 2500 University Drive NW, Calgary, AB T2N 1N4 Canada
AU: Partamies, N
EM: noora@phys.ucalgary.ca
AF: University of Calgary, Department of Physics and Astronomy, 2500 University Drive NW, Calgary, AB T2N 1N4 Canada
AU: Syrjaesuo, M
EM: mikko@phys.ucalgary.ca
AF: University of Calgary, Department of Physics and Astronomy, 2500 University Drive NW, Calgary, AB T2N 1N4 Canada
AU: Sangalli, L
EM: sangalli@phys.ucalgary.ca
AF: University of Calgary, Department of Physics and Astronomy, 2500 University Drive NW, Calgary, AB T2N 1N4 Canada
AB: During two observing campaigns in Churchill, Manitoba, Canada, we observed several instances of intense flickering aurora using an intensified TV camera (30 frames per second, 13x9.5 km field of view at 100 km) and a telescope-mounted channel photomultiplier (CPM, 1000 samples per second, 600 m diameter FOV at 100 km). In addition, a color all-sky camera was operated during one campaign to provide context. The TV images were divided into variable-sized regions of interest (ROI). Time-series analysis of these regions showed flicker at frequencies between 3-14 Hz . High-resolution spectral analysis reveals that individual flickering patches are composed of two or three discrete frequencies. For example, one event showed spectral peaks at 11, 13 and 14 Hz, and another at 5, 8, 10, and 11 Hz. The 15 Hz Nyqvist rate leaves the possibility of aliasing from frequencies just above 15 Hz. Spectrograms derived from CPM data showed prominent flicker from 2-15 Hz, a few weaker examples from 15-30 Hz, and none above 30 Hz. Flicker was most prominent for ROI below 700x700 m, suggesting a spatial scale for individual oscillating patches, since larger ROI tend to average over neighboring patches oscillating out of phase. Similarly, flicker became less pronounced for data windows longer than 5 s, indicating a maximum coherence time within a single ROI.
DE: 2704 Auroral phenomena (2407)
SC: SPA-Magnetospheric Physics [SM]
MN: Fall Meeting 2005