ATOC and other acoustic thermometry observations in New Zealand

A summary of participation of the New Zealand group in the ATOC (Acoustic Thermometry of Ocean Climate) program over a five year period is presented. Transmissions from Heard Island were observed in the Tasman Sea during the Heard Island Feasibility Test in 1991. The California-New Zealand underwater sound path was verified with explosive sources in 1992. Single hydrophone observations were made of transmissions to New Zealand from California from an, electrically driven source first suspended beneath a floating platform in 1994 and later placed on the ocean bottom at Pioneer Seamount in. 1995. Results from these experiments show that acoustic propagation to ranges of order 10 Mm appears to be characterised by large fluctuations occurring with a time scale of a few minutes.