Comparison of acceleration, expansion, and brightness of sprite streamers obtained from modeling and high-speed video observations

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Abstract

[1] We compare sprite streamer modeling results with high-speed video recordings of sprites made with 50-μs temporal resolution. Both the modeling results and the sprite videos show that sprite streamers propagate with acceleration and expansion during the initial stage of sprite development. The acceleration computed from the modeling for the applied electric fields close to the conventional breakdown threshold field is on the order of (0.5–1) × 1010 m s−2 and is in good agreement with the peak values observed experimentally. We further discuss the effects of different spatial and temporal resolutions of an observational system on the visual appearances of sprite streamers. It is found that the large variation in brightness of sprites estimated from several observational studies can be directly attributed to different temporal and spatial resolutions of used instruments. Mainly due to the increasing radius of the streamer head of an accelerating streamer, the brightness of the streamer head increases as well. The comparison results demonstrate that the brightness of a sprite streamer head increases exponentially with time and can span more than 4 orders of magnitude in a very short period of about 1 ms. We propose a method for remote sensing of the sprite-driving electric field in the mesospheric and lower ionospheric region by measuring the rate of the change of the brightness.

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