652 



Table 5. Existing Analog Submarine Ice Keel 

 Draft Acoustic Data 



Figure 15. Data Release Area and Historical 

 Submarine Tracks 



Table 6. Existing Digital (Magnetic Tape) 

 Records of a Submarine Ice Keel Draft 

 Acoustic Data 



under Ihe .Arctic ice. which have operational sensitivity. 

 However, as these events age, the secunty concerns diminish 

 and the Navy has openly discussed some Arctic cruises like 

 that of the Nautilus, and papers have been published using 

 such data. 



Certain classified aspects of under ice data sets could be 

 preserved while still providing the environmental community 

 with data that retain their usefulness. Although no raw data are 

 likely to be declassified soon, the Navy has agreed^ to provide, 

 in unclassified form, all existing submarine ice exercise 

 acoustic data taken within the geographic area shown in 

 Figure 15. This figure also shows a depiction of previously 

 released submarine tracks through 1982, 



This figure shows the boundaries of the area appnnril by the Navy iCNO) 

 in 1992 for release ofenvironmenial data from Arctic submarine exercises. 



Also shown for this area are tiie submarine tracks of Arctic ice exercises 

 through 1982. 



Present Navy policies require that in order to be released, 

 acoustic ice data lying within the designated area shown in 

 Figure 15 can be released only if the associated positional data 

 have been coarse grained in time and space. We have examined 

 this matter within context of the coarse graining parameters 

 specified by the Navy and see it as no impediment to full 

 scientific exploitation of the data. For future scientific Arctic 

 cruises, data release has been approved for the slightly larger 

 area shown in Figure 16. 



c. Scientific Utility 



Since Nansen's Arctic journey, drifting ice camps of various 

 sorts have been in operation for approximately 100 station- 

 years. Ice thickness observations obtained by drilling holes or 

 measuring ice freeboard have established an average ice 

 thickness in the central Arctic region of about 3 meters, with 

 a large variance on small spatial scales. However, from tliese 

 physical, location-specific data, over the past century no 

 discernible secular trend has been documented. 



Submarine ice profiles are a valuable data source for ice draft 

 and ice process studies. The spatial and the temporal coverage 

 that these data supply is imponant for investigations studying 

 both large- and small-scale vanations and trendr, in the state of 

 the ice pack. From the data that are ehgible for release, one 



"^The scientific community has yet !o "test" this policy wilh new data requests. 



24 



