EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Assimilation of atmospheric infrasound data to constrain tropospheric and stratospheric winds

Javier Amezcua1,2, Peter Nasholm3, Marten Blixt4, and Andrew Charlton-Perez1
Javier Amezcua et al.
  • 1University of Reading, Reading, United Kingdom (
  • 2UK National Centre for Earth Observation, United Kingdom
  • 3NORSAR, Norway
  • 4Blixt Geo AS, Norway

We use acoustical 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 back-azimuth direction of the incoming infrasound wave-fronts, 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. Information from both sources is 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, 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 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.  

How to cite: Amezcua, J., Nasholm, P., Blixt, M., and Charlton-Perez, A.: Assimilation of atmospheric infrasound data to constrain tropospheric and stratospheric winds, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8244,, 2020


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