Recent progress in nuclear test detection using infrasound technology

The high performances of the International Monitoring System infrasound network were very well demonstrated by the detection and analysis of many Ground Truth Events in various environmental conditions. This presentation highlights recent progresses based on an improved description of both signal and atmosphere. Firstly, progress concerns observations and data analysis of big data sets. The infrasound sensors provide broadband signals in the interest frequency range. However, signals are generally analyzed in several parallel frequency bands. The currently used Progressive Multi-Channel Correlation algorithm (PMCC) is now evolving to process the useful information in a broad standardized frequency range, leading to a more accurate characterization of both source and noise which could benefit to operational monitoring purposes. Secondly, progress concerns the development of experimental infrasound stations which form a dense infrasound network, especially in Europe, enhancing the detectability of infrasound events. Thirdly, progress concerns an improved representation of the atmosphere. Systematic processing highlights the necessity to improve propagation modeling in the wave guide between ground and stratosphere-mesosphere-thermosphere system to interpret the observations. The predicted detection periods of volcano eruptions using near field observations and propagation models are shorter than the periods observed in the far field. The lack of representation in the models of large scale atmospheric disturbances such as gravity, planetary waves and sudden stratospheric warming events, is at the origin of these differences. New methods are developed to parameterize these disturbances for further assimilation in atmospheric models, as planned in the framework of the Atmospheric dynamics Research InfraStructure in Europe (ARISE) project. One application is the improvement of the detection capability simulations used for the evaluation of the performances of existing networks and their optimization. Multi-instrument observations could be the next important step for the improvement of operational infrasound monitoring. The extension of meteorological information up to the stratosphere and mesosphere could significantly improve the characterization of the sources of interest.