Localization of Antarctic ice breaking events by frequency dispersion of the signals received at a single hydroacoustic station in the Indian Ocean

Transient acoustic signals from Antarctic ice cracking and breaking events, featuring significant frequency dispersion, were observed at the hydroacoustic stations deployed in the Indian Ocean as part of the International Monitoring System (IMS) of the Comprehensive Nuclear‐Test‐Ban Treaty. Based on a comparison with numerical predictions, the measured dispersion characteristics were used to estimate the range between ice events and the receiver. Combined with the bearing capability of the IMS stations, these estimates allow us to locate ice events from a single hydroacoustic station. An analysis of range estimation errors due to uncertainty of the measured time‐frequency structure of signal arrivals and due to variations of the sound speed profiles was also conducted. The analysis showed that the location accuracy from a single hydroacoustic station for the typical ice events was of the same order, as that determined from an intersection of bearings from two remote stations, if the signal frequency bandwidth is as wide as at least 5 Hz and lies within 5 Hz to 35 Hz frequency range. This localization method was examined by analysing several ice events detected at both the Cape Leeuwin IMS station and a sea noise logger deployed off the Antarctic shelf.