Lightning flashes have been observed by a number of missions that visited or flew by Jupiter over the past several decades. Imagery led to a flash rate estimate of about 4 × 10−3 flashes per square kilometre per year (refs. 1,2). The spatial extent of Voyager flashes was estimated to be about 30 kilometres (half-width at half-maximum intensity, HWHM), but the camera was unlikely to have detected the dim outer edges of the flashes, given its weak response to the brightest spectral line of Jovian lightning emission, the 656.3-nanometre Hα line of atomic hydrogen1,3–6. The spatial resolution of some cameras allowed investigators to confirm 22 flashes with HWHM greater than 42 kilometres, and to estimate one with an HWHM of 37 to 45 kilometres (refs. 1,7–9). These flashes, with optical energies comparable to terrestrial ‘superbolts’—of (0.02–1.6) × 1010 joules—have been interpreted as tracers of moist convection originating near the 5-bar level of Jupiter’s atmosphere (assuming photon scattering from points beneath the clouds)1–3,7,8,10–12. Previous observations of lightning have been limited by camera sensitivity, distance from Jupiter and long exposures (about 680 milliseconds to 85 seconds), meaning that some measurements were probably superimposed flashes reported as one1,2,7,9,10,13. Here we report optical observations of lightning flashes by the Juno spacecraft with energies of approximately 105–108 joules, flash durations as short as 5.4 milliseconds and inter-flash separations of tens of milliseconds, with typical terrestrial energies. The flash rate is about 6.1 × 10−2 flashes per square kilometre per year, more than an order of magnitude greater than hitherto seen. Several flashes are of such small spatial extent that they must originate above the 2-bar level, where there is no liquid water14,15. This implies that multiple mechanisms for generating lightning on Jupiter need to be considered for a full understanding of the planet’s atmospheric convection and composition. Small lightning flashes detected on Jupiter by Juno have shallow origins above the 2-bar level of Jupiter’s atmosphere where temperatures are too low for liquid water to exist.

中文翻译：

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来自木星浅层电风暴的小闪电

在过去的几十年里，许多访问或飞越木星的任务都观察到了闪电。图像导致估计的闪光率约为每年每平方公里 4 × 10−3 次（参考文献 1,2）。航海者号闪光的空间范围估计约为 30 公里（半最大强度下的半宽，HWHM），但相机不太可能检测到闪光的昏暗外边缘，因为它对最亮光谱的反应很弱。木星闪电发射线，656.3 纳米的氢原子 Hα 线 1,3-6。一些相机的空间分辨率允许研究人员确认 22 次 HWHM 大于 42 公里的闪光，并估计 HWHM 为 37 至 45 公里的一次（参考文献 1,7-9）。这些闪光的光能可与地球上的“超级闪电”相媲美——为 (0.02–1. 6) × 1010 焦耳——已被解释为源自木星大气 5 巴水平附近的湿对流示踪剂（假设光子从云层下方的点散射）1-3,7,8,10-12。先前对闪电的观察受到相机灵敏度、与木星的距离和长时间曝光（约 680 毫秒到 85 秒）的限制，这意味着一些测量可能是叠加的闪光报告为 one1,2,7,9,10,13。在这里，我们报告了朱诺号航天器对闪电的光学观测，其能量约为 105-108 焦耳，闪光持续时间短至 5.4 毫秒，闪光间隔为数十毫秒，具有典型的地球能量。闪光率约为每年每平方公里 6.1 × 10-2 次闪光，比迄今为止所见的要高一个数量级。一些闪光的空间范围如此之小，以至于它们必须起源于 2 巴水平以上，那里没有液态水 14,15。这意味着需要考虑在木星上产生闪电的多种机制，才能全面了解木星的大气对流和成分。朱诺号在木星上探测到的小闪电起源于木星大气层 2 巴以上的浅层，那里的温度太低，液态水无法存在。