are shown in both the slope of the sigma-t surface 

 and the nitrite distribution. The 27.0 sigma-t 

 surface slopes in varying degrees, from a level of 

 50 meters, westward to intersect with the bottom 

 along both the Baffin Island and Labrador coasts. 

 To the east of Resolution Island, the surface re- 

 mains quite level, at 50 meters, to within 20 miles 

 of the coast and then abruptly deepens southward 

 to a depth in excess of 250 meters. To the north 

 of Resolution Island, the surface dips slightly be- 

 low 150 meters before intersecting the bottom. 

 Here again is the indication of the existence of 

 lighter water to the south of the entrance to Hud- 

 son Strait. Lesser amounts of this light water 

 exists to the north of the strait entrance and is 

 virtually absent due east of Resolution Island. 



The circulation depicted by the nitrite concen- 

 tration supports the flow pattern shown by the 

 sigma-t surface slope. Water movement at these 

 depths are indicated as bemg into the strait on the 

 north, and south of Resolution Island and out in 

 the center of the entrance between Resolution 

 Island and Cape Chidley. The outflow of water 

 appears again to assume a slug or pulselike struc- 

 ture described by both the nitrite distribution and 

 the contours of the sigma-t depth topography. 

 In this case the water moving out of the entrance 

 appears to be of minimum nitrite concentration, 

 deflecting or distorting the water of higher con- 

 centrations which are flowing from the north, 

 immediately to the east of Resolution Island. 



DYNAMIC HEIGHT CHARTS 



A dynamic height chart of the area adjacent to 

 the entrance to Hudson Strait was constructed to 

 provide quantitative current information. This 

 chart is presented as figure 8. As previously 

 mentioned, all dynamic heights are computed rel- 

 ative to the 1,000-decibar level of assumed no 

 motion. No direct current measurements are 

 available in this area to provide a comparison with 

 absolute values. The concept of "relative"' cur- 

 rents is useful however; because the question of 

 relative contributions of the several water masses 

 in the area to the Labrador Current was the 

 primary concern of the expedition. 



One basic assumption required in the dynamic 

 treatment of oceanographic data is that of steady 

 state. That is, conditions are such in the area of 

 consideration, that the various forces acting on 

 the water are in a dynamic equilibrium. In the 

 steady state situation, an adequate description of 



the pressure distribution, resulting from the mass 

 distribution, will describe the water movements 

 relative to a reference level. 



There exists great doubt as to the existence of 

 any equilibrium attainment of the forces in the 

 vicinity of the entrance of Hudson Strait because 

 of tides and the resulting tidal currents. These 

 tidal movements result in water being moved in- 

 dependent of the more discrete pressure-mass dis- 

 tribution forces. The tides in this area are semi- 

 diurnal and relatively equal. With a discrete 

 pressure-mass distribution force impressed on the 

 oscillating tidal movement, the resulting net move- 

 ment would be governed by the direction of the 

 pressure-mass distribution force. It would be ex- 

 pected that this long term net movement would 

 be reflected in a description of the mass distribu- 

 tion obtained from the point sampling of tempera- 

 ture and salinity. A major redistribution of the 

 mass features in the entrance of Hudson Strait by 

 the tidal currents seems unlikely because of the di- 

 rectional changes of the tidal currents every 6 

 hours. With the quantities of water present, the 

 time frame for redistribution appears much t«o 

 short. 



The current and volume flow data calculated 

 from the mass distribution in the area would cer- 

 tainly not be representative of the instantaneous 

 particle movement, but should be representative 

 of the longer period movement tendencies. These 

 tendencies depicted by the mass distribution should 

 be comparable between the sections of the survey 

 area. With this assumption in mind, the dynamics 

 of the area are presented and extended, in a later 

 section, to include volume flow computations. 



Figure (8) shows the surface circulation in and 

 near the entrance to Hudson Strait. The circula- 

 tion, deduced by the dynamic method matches 

 quite well with qualitative flow depicted from the 

 isentropic distributions. A broad low-velocity 

 BaflSn Land current flows from the north towards 

 the entrance to Hudson Strait. A turning to the 

 right of the inshore filaments occurs, resulting in 

 water movement into the strait north of Resolu- 

 tion Island. A convergence of the broad current 

 band located further offshore occurs along with a 

 commensurate acceleration. This jet then flows in 

 to Hudson Strait just to the south of Resolution 

 Island. This is exactly what was indicated on the 

 27.0 sigma-t level shown in figure (7). The 26.2 

 sigma-t level, however, showed a shallow flow into 

 the strait north of Resolution Island. 



