Chapter V 

 THE DAVIS SECTOR 



THE SURFACE CURRENTS 



The name, ''Davis Strait", is used here for the narrow part of the 

 waterway' which separates Greenland and Baffin Land (p. 2). The 

 bathymetric map of this region (fig. 38) shows the two basins, 

 Labrador and Baffin, connected by a winding channel, which, as 

 marked by the 600 meters isobath, averages 40 miles in width and 

 with a threshold depth of 675 meters. Because all exchanges be- 

 tween the Labrador Sea and Baffin Bay necessarily have to pass 

 across this sill, particular investigation has been devoted to the Davis 

 Strait sector. Besides the Coast Guard's data, the Godthaab expedi- 

 tion's observations, Riis-Carstensen (1936), and the Michael Sars^ 

 observations. Martens (1929) have also been utilized. For the geo- 

 graphical position of the stations see figure 38. In constructing the 

 series of dynamic topographic maps shown in figure 39, GodthaaVs 

 station number 162, latitude 67°48.5' north, longitude 60°48' west, 

 was selected as the datum station for the surveyed area, except for 

 Marion stations 986 to 994, which have been referred to Marion sta- 

 tion 984, latitude 63° 10' north, longitude 56°32' west. The dynamic 

 heights for the above stations, similar to those of the Coast Guard, 

 have been computed in accordance with the anomaly tables published 

 bv Sverdrup (1933) and the method referred to by Helland-Hansen 

 (1934). 



It will be recalled from this theorem that if motionless water is 

 correctly assumed at the selected level (usually a deep level between 

 two deep-water stations), all motion is accounted for even at the 

 bottom of the shoalest .stations. An important step in the method, 

 however, is the correct determination or portrayal of the distribution 

 of the anomaly of specific volume along the bottom of the shoal water 

 stations in the section. That errors in the dynamic height and the 

 computed velocity at shoal water stations may result from the above 

 source was demonstrated in our work wdien a common inshore sta- 

 tion was approached along two converging .sections. For example, 

 the computed dynamic heights of station 45, based upon the distribu- 

 tion of specific volume in a vertical plane passed through station 

 42 and another plane passed through station 46, were 1,454.874 

 dynamic meters and 1,454.900 dynamic meters, respectively. A 

 similar discrepancy arose in the computed dynamic heights of sta- 

 tion 168 which were 1,454.879 and 1,454.823 dynamic meters by 

 different approaches. The difference in the first case when expresesd 

 in terms of motion introduces an error of 1.7 centimeters per sec- 

 ond, which is not great, but in the second case the difference repre- 

 sents a current of 7.3 centimeters per second, which is relatively 

 significant. When the dynamic values for each one of the stations 

 in the Davis Strait sector were plotted, and a topographic map at- 



66 



