Two gamma‐ray glows were observed by a high‐altitude NASA ER‐2 aircraft flying at 20 km altitude over a thunderstorm in Colorado, USA. The flux of the first glow rapidly intensified and then abruptly decreased within a few tens of milliseconds. On a timescale of seconds, the flux decrease occurred simultaneously with a hybrid intra‐cloud/cloud‐to‐ground lightning discharge beneath the aircraft. However, a more detailed analysis of the discharge dynamics indicated that the discharge activity was unusually calm during the actual period of the flux decrease. The lightning was observed with on‐board antennas, optical sensor, and ground‐based lightning mapping and location networks. Its closest activity was 12 km away from the aircraft, below and slightly ahead the course. The gamma‐ray flux reduction happened roughly in the middle of the lightning development process. The glow spectral analysis for the periods of a weak and strong flux enhancement has been done. The spectra were found to be background‐like and similar to each other.

中文翻译：

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从20 km高度观察到快速的伽马射线辉光通量减少

在美国科罗拉多州的一次雷暴中，一架高空NASA ER-2飞机以20公里的高度飞行，观测到两次伽马射线发光。第一辉光的通量在几十毫秒内迅速增强，然后突然下降。在几秒钟的时间尺度上，通量下降与飞机下方的云内/云对地混合雷电放电同时发生。但是，对放电动力学的更详细分析表明，在实际通量下降期间，放电活动异常平静。使用车载天线，光学传感器以及基于地面的闪电测绘和定位网络观察到了闪电。它最接近飞机的位置是距飞机12公里，位于航线下方和前方。伽马射线通量的减少大约发生在闪电发展过程的中期。已经完成了弱通量增强和强通量增强期间的辉光光谱分析。光谱被发现是类似背景的并且彼此相似。