Spatial characteristics of wave-like structures in diffuse aurora obtained using optical observations
We present the results of a statistical study using optical images from ALIS (Auroral Large Imaging System) to investigate the spatial and temporal variations of structures in diffuse aurora. Analysis of conjugate Reimei data shows that such fine structures are a result of modulation of high-ener...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2012-12-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/30/1693/2012/angeo-30-1693-2012.pdf |
| Summary: | We present the results of a statistical study using optical images from ALIS
(Auroral Large Imaging System) to investigate the spatial and temporal
variations of structures in diffuse aurora. Analysis of conjugate Reimei data
shows that such fine structures are a result of modulation of high-energy
precipitating electrons. Pitch angle diffusion into the loss cone due to
interaction of whistler mode waves with plasma sheet electrons is the most
feasible mechanism leading to high-energy electron precipitation. This
suggests that the fine structure is an indication of modulations of the
efficiency of the wave–particle interaction. The scale sizes and variations
of these structures, mapped to the magnetosphere, can give us information
about the characteristics of the modulating wave activity. We found the scale
size of the auroral stripes and the spacing between them to be on average
13–14 km, which corresponds to 3–4 ion gyro radii for protons with an
energy of 7 keV. The structures move southward with a speed close to zero in
the plasma convection frame. |
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| ISSN: | 0992-7689 1432-0576 |