Using a ground-based five-wavelength photometer, which has been operative in Tromsø, Norway since February 2017, we have statistically analyzed the lifetime of O( 1 S) to reveal the emission altitude of pulsating aurora (PsA). For the statistics, we have extracted intervals of PsA using an EMCCD all-sky imager on 37 nights during 3 months from January to March, 2018. By performing a cross-correlation analysis between the time-series of 427.8 nm (N 2 + first negative band) and 557.7 nm oxygen emissions, we derived the distribution of the lifetime of O( 1 S). The mean of the lifetime is 0.67 s and the mode is around 0.7 s. We estimated the emission altitude of PsA using the lifetime of O( 1 S) and then carried out a case study, in which we compared the temporal variations of the emission altitude with the peak height of E region ionization obtained from the simultaneous observation of the EISCAT UHF radar. We confirmed an overall agreement between the two parameters, indicating the feasibility of using the current method for estimating the energy of precipitating electrons causing PsA. In addition, we have derived the statistical characteristics of the emission altitude of PsA. The result shows that the emission altitude becomes lower in the morning side than in the midnight sector, which indicates that the energy of PsA electrons is higher in the later MLT sector. Especially, there is a decrease of the emission altitude at around 06 MLT. However, the model calculation infers that the energy of cyclotron resonance between magnetospheric electrons and whistler-mode chorus waves does not change so much depending on MLT. This implies that the observed change of the emission altitude cannot be explained only by the MLT dependence of resonance energy.

中文翻译：

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用五波长光度计估算脉动极光的发射高度

使用自 2017 年 2 月以来一直在挪威特罗姆瑟运行的地面五波长光度计，我们对 O( 1 S) 的寿命进行了统计分析，以揭示脉动极光 (PsA) 的发射高度。为了统计，我们在2018年1月至3月的3个月内，使用EMCCD全天像仪提取了37个晚上的PsA间隔。通过对427.8 nm（N 2 + first负波段）和 557.7 nm 的氧排放，我们推导出 O( 1 S) 的寿命分布。平均寿命为 0.67 s，模式约为 0.7 s。我们使用 O( 1 S) 的寿命估计了 PsA 的发射高度，然后进行了案例研究，其中我们将发射高度的时间变化与 EISCAT UHF 雷达同时观测获得的 E 区电离峰值高度进行了比较。我们确认了两个参数之间的总体一致性，表明使用当前方法估计引起 PsA 的沉淀电子能量的可行性。此外，我们还推导出了 PsA 发射高度的统计特征。结果表明，早晨侧的发射高度低于午夜扇区，这表明后期 MLT 扇区中 PsA 电子的能量较高。特别是在 06 MLT 附近，排放高度有所下降。然而，模型计算推断磁层电子与哨声模式合唱波之间的回旋共振能量不会因MLT而发生太大变化。这意味着观察到的发射高度的变化不能仅用共振能量的 MLT 依赖性来解释。