IIIII'»IMI 



Figure 54. Transparency measurements made 

 near the surface in the Bering and Chukchi 

 Seas. Values indicate depth in feet to which 

 a Secchi disc is visible from ship. 



The transparency is relatively high at stations north of 

 Cape Hope, as compared to stations in the Bering Sea, Kotzebue 

 Sound, or Norton Sound. A Secchi disc can be seen to an 

 average depth of 36 feet at these Chukchi Sea stations. A 

 visibility of 36 feet corresponds to poor transparency for 

 open sea conditions, but is much better than the visibility 

 found under average coastal conditions. 



AMBIENT NOISE 



During the cruise, ambient noise measurements were 

 made at the hydrographic stations in the Bering and Chukchi 

 Seas in order to obtain some information about the magnitude 

 and characteristics of ambient noise in arctic waters. To 

 avoid maintenance and operational difficulties aboard ship, 

 only a single unit of simple listening equipment was used. 

 This consisted of a Brush Manufacturing Company type C-23 

 hydrophone, an amplifier with attenuator and meter, and a 

 set of earphones. The response of the system was reasonably 



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