Modeling hydroacoustic waveform envelopes for comprehensive test-ban treaty monitoring

Robust and accurate localization of explosion events in the oceans requires modeling signal arrival times for a number of receivers. Additional information contained in the waveform envelope may also be used to recover other source properties and reduce the probability of false alarms in nuclear explosion monitoring. The feasibility of efficient envelope modeling was investigated by comparing adiabatic normal-mode model predictions with explosion data. The kraken computer code, com-bined with appropriate dispersion curve interpolation, was used to compute modal shapes and wave numbers in each range segment. To facilitate CTBT knowledge base development, the model has been used to illustrate the various factors that contribute to the shape of the received hydroacoustic waveform envelope, and provide design feedback for sensor placement and data analysis algorithms. The model was compared with data for two source–receiver paths: (a) the Chase21 ship scuttling explosion on 25 June 1970 off the New Jersey coast and recorded at the Ascension Island hydroacoustic array; and (b) nuclear explosions on Mururoa Atoll and received at the hydrophone at Point Sur, California. Adiabatic normal-mode approach was found inadequate for source and receiver located far from the SOFAR axis. [Work supported by U.S. DOE, Office of Nonproliferation and National Security.]