Infrasound is low-frequency (< 20 Hz) inaudible atmospheric sound. It can travel distances longer than 1000s of kms, and reach as high as 125 km in altitude before it returns to the ground. It can be used for detection and location of explosive events (meteors, volcanic eruptions, controlled explosions, nuclear explosions, rocket launches, accidents) and for atmospheric imaging.
The propagation of infrasound is affected by atmospheric parameters such as temperature and the strength and direction of the wind, which makes it a promising tool to remotely measure the atmospheric state at altitudes greater than 20 km, which is not well sampled by meteorological data but critical to modelling of the coupling between different parts of the atmosphere.
NORSAR operates several infrasound station on mainland Norway, at Karaksjok, Måselv and Løten and has access to data from other countries. We propose one to two projects on infrasound modelling using ground-truth events (well-known and located explosions) such as the extensive set of rocket launches from the Andøya Space Center and the ammunition destructions by the Finnish army, and testing different modelling methods.
One recent master project has just looked at how to produce acoustic profiles from meteorological data and started modelling of the infrasound with the refelctivity method. In the new project(s), the parameters of the reflectivity methods will be tuned and other modelling methods based on ray theory and possilby finite-differences will be tested.
- Programming in Python / Matlab / etc
- Statistics and data processing
- Numerical methods and wave-propagation simulation