Bogoslof volcano, a back-arc volcano in Alaska’s Aleutian arc, began an eruptive sequence in mid-December 2016 that ended in late August 2017, with 70 individual eruptive episodes. Because there were no local seismic or infrasound stations on the island, the Alaska Volcano Observatory (AVO) relied on distant geophysical networks and remote sensing techniques to assess activity during the eruption. AVO maintains six infrasound arrays to monitor activity along the Aleutian arc: Adak, the Island of Four Mountains, Okmok, Akutan, Sand Point, and Dillingham. Eruption detection at infrasound arrays is subject to local as well as mesoscale meteorological conditions that vary greatly over both short and long timescales. Infrasound detections from the array nearest to Bogoslof (Okmok), with a latency of about 3 min, played a crucial role in monitoring activity during the eruption. Despite the relative proximity of the Okmok array to Bogoslof (60 km), infrasound detections were not uniformly observed with only about two-thirds of the events successfully detected. The farthest array at Dillingham (816 km) detected approximately half of the explosive events, with all other arrays detecting less than half of the events. We compare observations with infrasound propagation model predictions, using both normal mode and parabolic equation forward models, to interpret the variation in detections of the 70 explosive events across the AVO infrasound network. The forward models utilize the newly created, publicly available AVO-G2S atmospheric reconstruction using numerical weather predictions data for the lower atmosphere, coupled with upper atmosphere empirical models of wind speeds and temperature. We find that long-range detections (> 100 km) of Bogoslof events are largely aligned with seasonal variability in favorable propagation conditions, while regional detections (< 100 km) are less consistent with propagation modeling. Understanding the output of numerical models in comparison to past observations will facilitate their use in future operational settings for AVO and other observatories.

中文翻译：

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阿拉斯加博戈斯洛夫火山不断发展的次声探测：来自大气传播模型的见解

博戈斯洛夫火山是阿拉斯加阿留申岛弧的弧后火山，于 2016 年 12 月中旬开始喷发，并于 2017 年 8 月下旬结束，共有 70 次喷发。由于岛上没有当地的地震或次声站，阿拉斯加火山观测站 (AVO) 依靠遥远的地球物理网络和遥感技术来评估喷发期间的活动。AVO 维护着六个次声阵列来监测阿留申岛弧沿线的活动：Adak、四山岛、Okmok、Akutan、Sand Point 和 Dillingham。次声阵列的喷发探测受当地和中尺度气象条件的影响，这些条件在短期和长期的时间尺度上变化很大。来自距离 Bogoslof (Okmok) 最近的阵列的次声检测，延迟约为 3 分钟，在监测喷发期间的活动方面发挥了至关重要的作用。尽管 Okmok 阵列与 Bogoslof（60 公里）相对接近，但并未均匀地观察到次声探测，只有大约三分之二的事件被成功探测到。Dillingham 最远的阵列（816 公里）检测到大约一半的爆炸事件，而所有其他阵列检测到的事件不到一半。我们使用正常模式和抛物线方程前向模型将观测结果与次声传播模型预测进行比较，以解释 AVO 次声网络中 70 个爆炸事件的检测变化。正向模型利用新创建的、公开可用的 AVO-G2S 大气重建，使用低层大气的数值天气预报数据，再加上风速和温度的高层大气经验模型。我们发现 Bogoslof 事件的远程检测（> 100 公里）在很大程度上与有利传播条件下的季节性变化一致，而区域检测（< 100 公里）与传播建模不太一致。与过去的观测相比，了解数值模型的输出将有助于它们在 AVO 和其他天文台的未来运行环境中的使用。