Oceanographic Conditions in Smith Sound and Northern Baffin Bay, 



September 1968 



Robin D. Muench * 



An IS day oceanographic survey of the North- 

 ern Baffin Bay-Smith Sound region was conduct- 

 ed aboard the CGC WESTWIND from 6-24 

 September 1968. This survey was part of the 

 North "Water Project, coordinated by the Arctic 

 Institute of North America and cooperative 

 among groups from the University of Washing- 

 ton, the U.S. Coast Guard, McGill University 

 and Dartmoutli College. Figure 1 shows the 

 WP^STWIND's cruise track for the survey. 



SCIENTIFIC BACKGROUND 



The primary oceanographic problem in the 

 nortliern portion of Baffin Bay is the origin of 

 the so-called "North Water". This feature, which 

 occupies approximately the area covered by the 

 cruise track of tiie WESTWIND, is a region 

 whicii remains essentially ice-free during the en- 

 tire year. It also acts as nucleus for ice disinte- 

 gration in the spring as the melt progresses in 

 the eastern Arctic. (For further details see Dun- 

 bar et ah, 1967.) Since winter climatic conditions 

 would seem to dictate the formation of a solid 

 ice cover, as is indeed the case to the north and 

 soutii of this area, some combination of meteoro- 

 logic and oceanographic processes must act to 

 maintain the open water during the winter 

 montlis. 



ILxplanutions which have been advanced for 

 the presence of the North Water during the win- 

 ter include: (a) Pliysical removal of new ic«, as 

 it forms, by the prevailing northeasterly winds 

 in combination with an "ice dam" in Smith 

 Sound wliich prevents ice from flowing south- 

 ward into the region, (b) A gyre circulation 

 whicli tends to remove the ice to the outside of 

 the gyre, (c) I^p welling of warm subsurface 

 Atlantic Water to provide a heat source and 

 consequently prevent ice formation. Despite these 

 theories, the phenomenon remains essentially un- 

 explained. 



1 Univorsity of Washington, Seattle, Washington 98105. 



A second problem in Baffin Bay is the mode of 

 formation of the Bottom Water ( -.38 to -.40°C, 

 34..5OV00). This water mass, which is found below 

 about 1800 m, has extremely uniform temperature 

 and salinity from year to year and throughout 

 its extent. It has not been observed to enter from 

 tlie south, via Davis Strait. Preliminary calcula- 

 tions show it unlikely that it forms within the 

 Bay itself by sinking and mixing of brine formed 

 by freezing. A remaining possible sourc« is sug- 

 gested by the presence of water with identical 

 properties at a depth of about '250 m in the 

 channel north of Smith Sound and northward 

 to the Arctic Ocean. This water type has, how- 

 ever, never been detected south of the 250 m sill 

 in Kane Basin just north of Smith Sound. It 

 seems possible that unusual conditions might al- 

 low tiie proper type of water to flow southward 

 througii Smith Sound into Baffin Bay intermit- 

 tently and so contribute to the Bottom Water. 

 Such an event has never been observed, however. 

 That the Bottom Water may be replenished 

 either very .slowly or else intermittently is in fact, 

 suggested by its low dissolved oxygen concentra- 

 tions. 



In addition to the above specific problems, little 

 is known about the general circulation and dis- 

 tribution of temperature and salinity in northern 

 Baffin Bay. Further knowledge of these is perti- 

 nent to the North Water and Bottom Water 

 problems, as well as to a better understanding 

 of the overall hydrography of Baffin Bay. 



A major lack in our knowledge of Baffin Bay 

 and the eastern Arctic in general lies in the fact 

 that no winter data have ever been acquired there. 

 All existing data from Baffin Bay have been col- 

 lected during the months June through October. 

 The circulation and water masses of at least the 

 upper layers of Baffin Bay possibly are different 

 during the winter. Such differences could only 

 be detected by conducting a winter oceanographic 

 cruise in the area. 



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