35 



determine if measurements of ocean sound speed over long distances 

 can be made with sufficient precision and stability to allow bulk 

 ocean temperatures to be extracted. This project, ATOC (Acoustic 

 Thermometry of Ocean Climate), uses the Navy's SOSUS system as 

 receivers of signals generated by distant sound sources. Measured 

 travel times give average temperatures along acoustic paths 

 integrated over distances of the order of 10,000 km. This three 

 year project was begun by the Advanced Research Projects Agency 

 (ARPA), under SERDP funding, to demonstrate the technique, with a 

 long term measurement program expected to follow. The measurement 

 results of ATOC will be assimilated into coupled ocean-atmosphere 

 models, significantly reducing critical uncertainties in the 

 predictions of these models and an improved understanding of the 

 rate of climate change. 



National Technical Means (NTM) 



Various sensor systems which collectively are designed as NTM 

 may also have applications to ocean science. Potential 

 applications include monitoring ocean pollution, studying small 

 scale ocean circulation structures, and assisting in field 

 experiments . Additional details can only be provided within an 

 appropriate classified forum. 



Enabling Capabilities 



There are a number of classified systems and databases which, 

 if made available to the ocean science community, would very 

 significantly improve its measurement and data distribution 

 capabilities . 



Precision-made navigation data from GPS has clear 

 applicability to a host of oceanographic measurement problems. 

 Some oceanographic applications require real-time data, while for 

 others delayed reconstruction of navigation will suffice. 

 Differential GPS is normally not possible in oceanographic 

 applications. As the importance of small scale processes grows, 

 accurate navigation is critical to a growing variety of ocean 

 experiments. In addition, some special large scale measurements, 

 such as acoustic thermometry, require high-accuracy navigation. In 

 general, the required accuracy cannot be obtained from unclassified 

 GPS data, nor ar ocean applications amenable to differential GPS as 

 are many land applications. 



Much GEOSAT altimetry mission data in the southern hemisphere 

 have been released. Availability of the 18 months of repeat 

 mission data over the northern hemisphere would be important to the. 

 investigation fo seasonal variability of mesoscale ocean features. 



It may be that the combination of the Navy's classified GDEM 

 (Generalized Digital Environmental Model) oceanographic model, 

 along with its oceanographic databases, could be used to obtain an 

 indication of past ocean warming. This issue should be explored. 



Submarines are a unique dual-use asset as oceanographic 

 measurement platforms. They can collect data from within the 



