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首页> 外文期刊>Journal of atmospheric and solar-terrestrial physics >Optical and VLF radio observations of sprites over a frontal storm viewed from O'Brien Observatory of the University of Minnesota
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Optical and VLF radio observations of sprites over a frontal storm viewed from O'Brien Observatory of the University of Minnesota

机译：从明尼苏达大学奥布莱恩天文台观测到的正面风暴上的小精灵的光学和VLF无线电观测

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Video images, and photometric and VLF data, were obtained by the University of Minnesota SKYFLASH system of 38 'sprite' events associated with a strong frontal system located in the upper midwest, U.S.A., on 20-21 June 1996. Besides two image-intensified TV cameras, the SKYFLASH system included telescopic photometers sensitive to Rayleigh scattered lightning flashes by viewing the zenith over the station (O'Brien Observatory, University of Minnesota, about 40 km NE of Minneapolis-St Paul) and also several VLF channels with 300 Hz to 10 kHz bandwidth for recording the electromagnetic 'sferics'. The sprites covered a wide range of sizes, from small kilometer-size filaments to huge luminous objects 50-60 km in lateral dimension. All the sprites appeared to consist of bundles of filaments, and always followed-within several ms-a 'trigger' could-ground discharge which, in 35 of the 38 events, was positive. It is difficult to find physical mechanisms that explain this positive stroke preference. The larger events reached from 80 km almost to cloud tops, but the small events were localized near 60 km altitude, which is the 'bright' region of sprite luminosity, a fast also not well explained theoretically. The filamentary structure of sprites also presents challenges to explain. Of about a dozen lightning storms observed with SKYFLASH in the period from 1993 to 1996 in the upper midwest, only two had an appreciable number of sprites.
机译：视频图像以及光度和VLF数据是由明尼苏达大学SKYFLASH系统于1996年6月20日至21日通过位于美国中西部上空的强锋系统与38个“ sprite”事件相关的获得的。此外，还有两个图像增强了电视摄像机，SKYFLASH系统包括可伸缩的光度计，该光度计可通过观测车站上方的天顶（明尼苏达大学奥布莱恩天文台，明尼阿波利斯-圣保罗东北约40公里）对瑞利散射闪电敏感，还包括多个300 Hz的VLF频道至10 kHz的带宽，用于记录电磁“铁氧体”。精灵覆盖的尺寸范围很广，从小到一公里的灯丝到横向尺寸为50-60 km的巨大发光物体。所有的精灵似乎都由成束的细丝组成，并且总是在几毫秒内跟随着“触发”可能的接地放电，在38个事件中有35个是阳性的。很难找到解释这种积极的中风偏爱的物理机制。较大的事件从80 km几乎到达云顶，但是较小的事件则定位在60 km的高度附近，这是精灵光度的“明亮”区域，这种快速现象在理论上也不能很好地解释。精灵的丝状结构也提出了挑战。在1993年至1996年期间，中西部上空观测到约12场SKYFLASH闪电风暴，其中只有2具相当数量的精灵。

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