BUCK: ARCTIC ENVIRONMENTAL LF ACOUSTICS MEASUREMENTS, 

 MODELS AND PLANS 



Because of the lack of a good logistics support capability, con- 

 trolled experimental data have been difficult to come by. The U.S. 

 has lacked a good remote telemetry station capability such as the 

 Russians have in their DARMS (Drifting Automatic Remote Meteorological 

 Stations) , and almost all of the acoustic data have been taken from 

 noisy, expensive, manned ice camps. In 1970, however, we had the first 

 opportunity for operating two floe stations exclusively for underwater 

 acoustics measurements, shown in Figure 4 as 5 and 6 (for Arctic Research 

 Lab Ice Station ARLIS-5 and ARLIS-5) , simultaneously with an ice island 

 (T3) . At these stations we had hydrophones at 30, 100, and 200 feet 

 for sampling the propagation and the ambient noise. We expended over 2 

 tons of explosives in charges ranging from blasting caps to over 100 

 pounds each, while the stations drifted with the pack, allowing different 

 path bottom topography. There were no man-made noise sources or 60-cycle 

 generators within 100 miles of the floe stations during the measurements. 

 The experiment lasted for over 2 months during the spring of 1970. 

 While other acoustics measurements had been made at various floe stations 

 before 1970, none had been so extensive or under such controlled condi- 

 tions. Most of the data shown in the next figures were taken during this 

 experiment. Almost all of the remaining acoustics measurements made in 

 the Central Arctic have been made from ice island stations. Ice islands 

 are very large (T3 is 7 x 4 miles, 100 feet thick, and a 3 billion ton 

 solid chunk of ice) broken-off pieces of glacial ice from Ellesmere 

 and have their own acoustic properties, not necessarily characteristic 

 of pack ice. They are extremely rare but sought out as scientific 

 platforms because of the permanence and, therefore, logistic economy 

 they afford. 



Almost all propagation work in the Arctic has been done with 

 underwater explosives and few CW projectors have been employed. 



733 



