Infrasound detection of the Chelyabinsk meteor at the USArray
Infrasound detection of the Chelyabinsk meteor at the USArray
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DOI：
10.1016/j.epsl.2014.01.031
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发表时间：
2014-09-15
影响因子：
5.3
通讯作者：
Hedlin, Michael A. H.
中科院分区：
文献类型：
--
作者：
de Groot-Hedlin, Catherine D.;Hedlin, Michael A. H.
2013年2月15日，一颗小行星在俄罗斯车里雅宾斯克附近进入地球大气层。这一极其罕见的事件被部署在美国大陆和阿拉斯加的400站USAray记录下来。这些观测站记录了这次事件产生的次声信号，其距离为6000至10，000公里，范围横跨北极点周围的55度扇形区域。这一密集、广泛的网络使人们得以详细研究远距离次声传播和声源特征。我们在所有的站（范围超过100分钟），但在整个网络的波列的字符明显的变化观察到长的波列。通过时空变化的大气模型进行的射线追踪表明，源激发的热层管道中的所有站点的共振。共振也被激发在源和站之间的持续平流层管道在阿拉斯加和沿着美国西海岸由于有利的风在这些方位角，导致更高的群速度和频率内容在这些站比东部。从抛物线方程模拟得出的衰减公式用于估计所有台站的次声传播损失，使用有效声速沿着每个源-接收器路径的简化模型。观测到的信号能量变化从高于美国东部热层管道台站的预期到低于阿拉斯加台站的预期，方位角几乎垂直于小行星的马赫锥，导致我们得出结论：（1）源主要是各向同性的，（2）模型高估了热层管道中的衰减。(C)2014爱思唯尔有限公司版权所有。
On February 15, 2013 a small asteroid entered Earth's atmosphere near Chelyabinsk, Russia. This extremely rare event was recorded by the 400-station USArray deployed in the continental United States and Alaska. These stations recorded infrasound signals from the event at distances from 6000 to 10 000 km across a sector spanning 55 degrees that encompassed the North Pole. This dense, extensive network permitted a detailed study of long-range infrasound propagation and source characteristics. We observe long wavetrains at all stations (ranging to over 100 min) but clear variations in the character of the wavetrains across the network. Ray-tracing through a spatially and temporally varying atmospheric model indicates the source excited resonance in the thermospheric duct to all stations. Resonance was also excited in a persistent stratospheric duct between the source and stations in Alaska and along the west coast of the United States due to favorable winds at those azimuths, leading to higher group velocities and frequency content at these stations than those to the east. An attenuation formula derived from parabolic equation simulations is used to estimate infrasound transmission losses at all stations, using simplified models of the effective sound speed along each source-receiver path. Observed variations in signal energies from higher than expected at stations in the thermospheric duct in the eastern United States, to lower than expected in Alaska, at azimuths nearly orthogonal to the asteroid's Mach cone, lead us to conclude that (1) the source was dominantly isotropic and (2) the model overestimates attenuation in the thermospheric duct. (C) 2014 Elsevier B.V. All rights reserved.