During a winter thunderstorm on 6 February 2017 in Japan, photonuclear reactions such as ¹⁴N(γ, n)¹³N were triggered by a downward terrestrial gamma‐ray flash (TGF), as reported by Enoto et al. (2017, https://doi.org/10.1038/nature24630). In the present paper, we compare the observation with a simulation model of downward TGFs and subsequent photonuclear reactions constructed by the first paper of the series and Wada, Enoto, Nakazawa, et al. (2019, https://doi.org/10.1103/physrevlett.123.061103). The observation and model consist of three components: annihilation gamma rays from positrons produced by β⁺‐decay nuclei, deexcitation gamma rays originating from neutron captures, and radiation doses by TGF photons. Each component of the observation is reproduced by the simulation model, and we constrain a relation between the number of avalanche electrons and their production altitude of the downward TGF. The constraints by three components match within an order of magnitude. The downward TGF is estimated to comprise (0.5–2.5) × 10¹⁹ avalanche electrons above 1 MeV produced at an altitude of 1.4–2.7 km. Despite differences in altitude, direction, and season, downward TGFs in winter thunderstorms are thought to have the same mechanism of electron acceleration and multiplication in lightning as TGFs observed by in‐orbit satellites.

中文翻译：

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闪电中的光核反应：2.观测模型与模拟模型的比较

根据Enoto等人的报道，在2017年2月6日的日本冬季雷暴期间，向下的地面伽马射线闪光（TGF）触发了光核反应，例如¹⁴ N（γ，  n）¹³ N. （2017，https://doi.org/10.1038/nature24630）。在本文中，我们将观察结果与向下转化生长因子的模拟模型以及随后由该系列的第一篇论文以及Wada，Enoto，Nakazawa等人构建的光核反应的模拟模型进行比较。（2019，https://doi.org/10.1103/physrevlett.123.061103）。观测和模型包括三个部分：β ⁺产生的正电子an灭伽玛射线衰变核，源自中子俘获的消磁伽玛射线以及TGF光子的辐射剂量。观测的每个分量都由模拟模型重现，并且我们限制了雪崩电子的数量与其向下TGF的产生高度之间的关系。三个分量的约束在一个数量级内匹配。估计向下的TGF包括1.4-2.7 km高度产生的1 MeV以上的（0.5-2.5）  ×  10 ^19个雪崩电子。尽管高度，方向和季节有所不同，但冬季雷暴中的向下TGF仍被认为与在轨卫星观测到的TGF具有相同的电子加速和倍增机理。