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of ships, and tracking stations around the world. 



The Navy's undersea surveillance system lUSS, is a highly capable 

 military system that provides an unmatched acoustic observatory into the ocean 

 for both Navy and civilian applications. lUSS has the potential to contribute to 

 nationally Important scientific and civil applications, as well as to develop 

 advanced acoustic remote sensing means to better understand the dynamics 

 and three dimensional temperature structure of the ocean. Recognizing that 

 potential, the Navy has sponsored various R&D projects that utilize lUSS 

 system components. 



One of the earliest applications of lUSS came over a decade ago, when 

 the Navy co-sponsored research with the National Science Foundation to 

 develop acoustic techniques as a means of observing changes in ocean 

 temperature over basin scales. This technique, called acoustic tomography, 

 provided the Navy with a new means of understanding ocean circulation and 

 temperature changes for use in acoustic studies. 



In addition to lUSS receivers which were used for acoustic tomography 

 experiments, we also made available our large, high-powered acoustic sources 

 to the civilian community for the conduct of the Heard Island Experiment. This 

 experiment demonstrated clearly the capability to monitor sound transmission 

 over thousands of miles for the purpose of assessing the feasibility of using 

 acoustic transmission paths to measure long-term temperature changes in the 

 ocean, and hence possible climate changes. As a consequence of the 

 capabilities provided by the Navy from lUSS and Navy sponsored research, a 

 major new project referred to as Acoustic Thermometry of the Ocean (ATOC) 



