Processing and analysis of infrasound data at the Comprehensive Nuclear Test Ban Treaty International Data Center

The Center for Monitoring Research (CMR) in Arlington, VA served as a prototype of the International Data Center (IDC) that is specified in the Comprehensive Nuclear Test Ban Treaty (CTBT). The CMR developed the software that is now being used by the IDC that has been established in Vienna to acquire, process, and analyze data from the global networks of hydroacoustic, infrasonic, radionuclide, and seismic sensors that are being installed to assist verification of the CTBT. The prototype IDC tested this software and related procedures very extensively with seismic and radionuclide data, but the infrasonic aspects of the system are less advanced due to the limited number of sensors available and a less complete knowledge of sources and signal propagation. The infrasonic processing system attempts to detect signals of interest by combining spatial coherence and power, and estimates signal arrival time, direction of approach, velocity, and other parameters. After a signal is detected, further processing is carried out to try to identify ‘‘phases’’ that correspond to reflections from different atmospheric layers. Finally, detections at multiple sensors of all types (seismic and hydroacoustic as well as infrasonic) are combined to estimate the time and location of potential sources.