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Assimilation of atmospheric infrasound data to constrain tropospheric and stratospheric winds
Quarterly Journal of the Royal Meteorological Society ( IF 8.9 ) Pub Date : 2020-05-12 , DOI: 10.1002/qj.3809
Javier Amezcua 1 , Sven Peter Näsholm 2 , Erik Mårten Blixt 2, 3 , Andrew J. Charlton‐Perez 4
Affiliation  

This data assimilation study exploits infrasound from explosions to probe an atmospheric wind component from the ground up to stratospheric altitudes. Planned explosions of old ammunition in Finland generate transient infrasound waves that travel through the atmosphere. These waves are partially reflected back towards the ground from stratospheric levels, and are detected at a receiver station located in northern Norway at 178 km almost due north from the explosion site. The difference between the true horizontal direction towards the source and the backazimuth direction (the horizontal direction of arrival) of the incoming infrasound wavefronts, in combination with the pulse propagation time, are exploited to provide an estimate of the average cross‐wind component in the penetrated atmosphere. We perform offline assimilation experiments with an ensemble Kalman filter and these observations, using the ERA5 ensemble reanalysis atmospheric product as background (prior) for the wind at different vertical levels. We demonstrate that information from both sources can be combined to obtain analysis (posterior) estimates of cross‐winds at different vertical levels of the atmospheric slice between the explosion site and the recording station. The assimilation makes greatest impact at the 12–60 km levels, with some changes with respect to the prior of the order of 0.1–1.0 m·s−1, which is a magnitude larger than the typical standard deviation of the ERA5 background. The reduction of background variance in the higher levels often reached 2–5%. This is the first published study demonstrating techniques to implement assimilation of infrasound data into atmospheric models. It paves the way for further exploration in the use of infrasound observations – especially natural and continuous sources – to probe the middle atmospheric dynamics and to assimilate these data into atmospheric model products.

中文翻译:

吸收大气次声数据以限制对流层和平流层风

这项数据同化研究利用爆炸中的次声来探测从地面到平流层高度的大气风分量。芬兰计划中的旧弹药爆炸会产生瞬发的次声波,并穿过大气传播。这些波从平流层水平反射回地面,在位于挪威北部距离爆炸地点约178公里的接收站处被探测到。朝向源头的真实水平方向与入射次声波阵面的后方位角方向(到达的水平方向)之间的差异,结合脉冲传播时间,可用来估算声源中平均横风分量。渗透的气氛。我们使用集合卡尔曼滤波器和这些观测值进行离线同化实验,并使用ERA5集合再分析大气产物作为不同垂直水平风的背景(先前)。我们证明,可以将来自两个源的信息进行组合以获得爆炸位置和记录站之间大气层在不同垂直高度的侧风的分析(后验)估计。同化作用在12–60 km的水平上影响最大,相对于先验值0.1–1.0 m·s有所变化 我们证明,可以将来自两个来源的信息进行组合,以获得爆炸地点和记录站之间大气层在不同垂直高度的侧风的分析(后验)估计。同化作用在12–60 km的水平上影响最大,相对于先验值0.1–1.0 m·s有所变化 我们证明,可以将来自两个源的信息进行组合以获得爆炸位置和记录站之间大气层在不同垂直高度的侧风的分析(后验)估计。同化作用在12–60 km的水平上影响最大,相对于先验值0.1–1.0 m·s有所变化-1,其大小比ERA5背景的典型标准偏差大。较高水平的背景方差减少通常达到2–5%。这是第一个发表的研究,展示了将次声数据同化到大气模型中的技术。它为利用次声观测(尤其是自然和连续源)进行进一步的探索铺平了道路,以探测中间的大气动力学并将这些数据同化为大气模型产品。
更新日期:2020-05-12
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