Oceanographic Conditions In Disko Bay and 

 Southeastern Baffin Bay In 1968 



Martin J. Moynihan and Edward J. Tennyson, Jr/ 



INTRODUCTION 



The primary source of the icebergs wliich en- 

 danger shipping in the Grand Banks region of 

 the North Atlantic Ocean is found in the West 

 Greenhmd ghiciers fronting on Baffin Bay. The 

 XLS. Coast Guard's International Ice Patrol has 

 identified twenty-one major iceberg producing 

 glaciers on the western coast of Greenland 

 (Smith, 1931). An Ice Patrol expedition to study 

 the variation of these glaciers was conducted in 

 1940 (Smith, 1941). Changes in iceberg distribu- 

 tion during recent years have indicated a possi- 

 bility of significant alterations in iceberg pro- 

 duction patterns of the West Greenland glaciers 

 or in the flow patterns in Baffin Bay. 



The investigation of the West Greenland gla- 

 ciers was renewed during the period of 18 July - 

 5 August 1968 when the l\SCGC EASTWIND 

 (WAGB 279) conducted the first phase of a 

 planned multi-year series of combined glaciologi- 

 cal surveys and oceanographic investigations 

 along the west coast of Greenland. The principal 

 task of this expedition was to survey the termini 

 of the tidewater glaciers of Northwest Bay and 

 Disko Bay (fig. 1) to determine differences be- 

 tween existing conditions and historical data. 

 Future cruises will include investigations of all 

 the major West Greenland tidewater glaciers 

 from Jakobshavn Fjord to Kane Basin. The sur- 

 vey and glaciological data will be published in a 

 separate Coast Guard publication after all of 

 the major glaciers have been studied. The ocean- 

 ographic data are being presented in a series of 

 Coast Guard Oceanographic Reports on Baffin 

 Bay. 



DISCUSSION 



Twenty-five oceanographic .stations were occu- 

 pied in the fjords and coastal waters of south- 

 eastern Baffin Bay (fig. 2) from 21 July to 5 



' Coa.st Guard Oceanographic Unit, Washington, D.C. 

 20390. 



August 1968 to survey the oceanic conditions 

 affecting the flow of icebergs. Temperature data 

 and water samples were collected by Nansen casts. 

 Water samples were analyzed for salinity and 

 oxygen concentrations on board the USCGC 

 EASTWIND during the cruise. The resulting 

 data were processed later at the Coast Guard 

 Oceanographic Unit in AVashington, D.C, with 

 a PDP-5 computer. Bottom photographs were 

 taken in the fjords and benthic organisms were 

 retrieved with a Van Veen bottom grab as time 

 permitted. 



The waters of southeastern Baffin Bay are af- 

 fected by the Davis Strait ridge which blocks the 

 flow of deep water between Baffin Bay and the 

 Labrador Sea. The West Greenland Current flows 

 northward a .oss the shallower eastern side of 

 the ridge and along the western coast of Green- 

 land. The Canadian Current flows southward 

 along the western side of Baffin Bay and is de- 

 flected eastward as the bottom rises towards the 

 ridge. 



Temperatures of 1°C to 4.7°C were found in 

 the waters of the upper 50 meters in Disko Bay 

 with a layer of water of less than 1°C at 100 

 meters (fig. 3). The warm saline deep water in 

 Disko bay (>2°C, >34%o) and the relatively 

 high percentage oxygen saturation all appear to 

 indicate that this bottom water is periodically 

 renewed by an intrusion of West Greenland Cur- 

 rent Water (figs. 3-5). 



Warm AVest Greenland Current Water (2.5°C, 

 34.5%o) was found at 300 meters between stations 

 17 and 19 along the break in the continental 

 shelf (figs. 3-4). Baffin Bay Deep Water (<1.8°C, 

 <34.5%o) was found below 700 meters Ijetween 

 stations 19 and 25 (figs. 6-7). Dunbar (1951) 

 reports this deep water to be deflected eastward 

 as the bottom shallows towards Davis Strait and 

 recirculated into Baffin Bay. 



Several of the fjords investigated were expected 

 to be anaerobic near the bottom. However, an 

 abundance of benthic fauna, as evidenced by both 



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