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SKACWAY 







Aj- STUDY AREA 





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Figure 1. — Auke Bay, Alaska, and surrounding area. 



2). The maximum depth, 100 m, is near the south end of 

 Coghlan Island; depths of 40 to 60 m are common over 

 much of the bay. 



Auke Bay is not a fiord-type estuary of the form de- 

 scribed by Pritchard (1952), but is a small tributary em- 

 bayment to a system of large fiords. Lynn Canal-Icy 

 Strait-Chatham Strait and Stephens Passage-Frederick 

 Sound-Chatham Strait are major interconnected pas- 

 sages in southeastern Alaska and provide communication 

 between Auke Bay and the Gulf of Alaska. The entire 

 region was heavily glaciated during the Pleistocene 

 Eopch. Martin and Williams (1924) concluded that gla- 

 cial deepening of a preexisting river valley was the pri- 

 mary process in the formation of the Chatham Strait- 

 Lynn Canal fiord. Auke Bay may have formed as a side 

 valley of the larger fiord system. 



Climatology 



Auke Bay lies within that part of the maritime 

 province extending along the northwest coast of North 

 America. Winds in this area are predominantly southerly 

 off the Pacific Ocean. These warm, moisture-laden winds 

 strike the high coastal ranges and result in abundant 

 precipitation, little sunshine, and moderate air 

 temperatures. Observations by the National Weather 

 Service at the Juneau Airport 3 km east of Auke Bay are 



that precipitation in the area is lightest in the spring and 

 heaviest in the fall (Fig. 3). Between February and May 

 the average monthly precipitation rate is fairly constant 

 (the monthly average for 1931-60 was 6.6 cm). Precipita- 

 tion increases rapidly in June and reaches a maximum in 

 October (the 30-yr average for October 1931-60 was 21.3 

 cm)/ After the October maximum, precipitation 

 decreases until February. 



The average monthly insolation for the Auke Bay area 

 from 1959 to 1962 is shown in Figure 4. Insolation, which 

 we estimated from cloud cover data, is a predominant 

 factor in controlling seasonal cycles of air and sea sur- 

 face temperature. Data from Roden (1959) on the total 

 amount of radiation received at sea level under cloudless 

 skies were converted to insolation under cloud cover ac- 

 cording to the equation of Sverdrup et al. (1942): 



Qi= Q (l-0.071 C) 



where Q : = radiation received at sea level adjusted for 



cloud cover 

 Q = total incoming radiation under cloudless 



skies 

 C = amount of clouds (in tenths of sky covered). 



•The average was calculated from data in the U.S. Weather Bureau's 

 annual publication Climatological Data, vols. 17-46, Alaska section (No. 

 13). 



