Lightning radiometry in visible and infrared bands
Lightning radiometry in visible and infrared bands
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DOI：
10.1016/j.atmosres.2023.106855
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发表时间：
2023-09
影响因子：
5.5
通讯作者：
Jacob Wemhoner;Lydia Wermer;C. D. da Silva;Patrick Barnett;C. Radosevich;Sonal Patel;H. Edens
中科院分区：
文献类型：
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作者：
Jacob Wemhoner;Lydia Wermer;C. D. da Silva;Patrick Barnett;C. Radosevich;Sonal Patel;H. Edens
闪电光发射的校准测量对于量化闪电在大气中的影响和设计具有足够动态范围的探测仪器能够产生接近100%的探测效率都至关重要。然而，迄今为止，只有有限数量的调查试图采取这种校准测量。在这项工作中，我们报告的功率辐射的闪电在可见光和红外波段，假设各向同性发射，并占大气吸收。更准确地说，我们报告的峰值辐射功率和总辐射能量的组合可见光和近红外范围（VNIR，0.34-1.1 μm），周围的H α线（652-667 nm），并为2-2.5 μm的红外波段。估计的峰值功率和总能量辐射的负云对地回击在VNIR范围内分别为130兆瓦和20千焦。此外，我们在H α和红外波段分别检测到12和0.19 MW的峰值辐射功率。我们交叉引用的光学数据集与闪电探测网络报告的峰值电流。由此产生的趋势是H α线周围发射的光功率根据指数等于1.25的幂律与峰值回击电流成比例。这一趋势在整个可见光谱范围内应该是近似真实的，可以归因于闪电回击通道的等离子体负微分电阻。最后，我们讨论了在不同波段进行闪电光功率校准测量的挑战，并将结果与先前收集的数据进行比较，这些数据具有不同的实验设置、观测条件和校准方法。
Calibrated measurements of lightning optical emissions are critical for both quantifying the impacts of lightning in our atmosphere and devising detection instruments with sufficient dynamic range capable of yielding close to 100% detection efficiency. However, to date, there is only a limited number of investigations that have attempted to take such calibrated measurements. In this work, we report the power radiated by lightning in both visible and infrared bands, assuming isotropic emission, and accounting for atmospheric absorption. More precisely, we report peak radiated power and total radiated energy in the combined visible plus near-infrared range (VNIR, 0.34–1.1 μm), around the H α line (652–667 nm), and for the 2–2.5 μm infrared band. The estimated peak power and total energy radiated by negative cloud-to-ground return strokes in the VNIR range is 130 MW and 20 kJ, respectively. Additionally, we detected peak radiated powers of 12 and 0.19 MW in the H α and infrared bands, respectively. We cross-reference the optical data set with peak current reported by a lightning detection network. The resulting trend is that optical power emitted around the H α line scales with peak return stroke current according to a power law with exponent equal to 1.25. This trend, which should be approximately true across the entire visible spectrum, can be attributed to the plasma negative differential resistance of the lightning return stroke channel. We conclude by discussing the challenges in performing calibrated measurements of lightning optical power in different bands and comparing the results with previously-collected data with different experimental setups, observation conditions, and calibration methods.