Contribution to and Effect of the Hudson Strait Outflow on 



the Labrador Current 



By Ronald C. Kollmeter, U.S. Coast Guard 



INTRODUCTION 



An oceanogi-aphio expedition to the western 

 Labrador Sea, under the control of the Interna- 

 tional Ice Patrol Section of the Coast Guard 

 Oceanographic Unit, Washington, D.C., was con- 

 ducted during July and August of 1965. The 

 purpose of the expedition was to gather quantita- 

 tive physical and chemical data from the upper 

 reaches of the Labrador Current. The survey 

 trackline and station locations are shown in figure 

 1. 



Knowledge of the circulation of the upper 

 reaches of the Labrador Current, and its relation- 

 ship to the Hudson Strait entrance, Baffin Land 

 Current, and the western Labrador Sea has been 

 primarily derived from Smith (1937). His stud- 

 ies were based on the various cruises of the Coast 

 Guard cutters MARION and GENERAL 

 GREENE. This work has formed the heart of 

 the published information concerning the area. 

 In recent years, Dunbar (1951) has discussed the 

 entire region, including the area west of the Hud- 

 son Strait entrance and cited the lack of quantita- 

 tive knowledge in the Baffin Bay, Labrador Sea, 

 and Hudson Strait areas. 



The main circulation features postulated by 

 Smith (1937) are shown in figure 2. The pri- 

 mary interest of the present investigation con- 

 ducted by the International Ice Patrol, centers 

 around the entrance to Hudson Strait. As can be 

 seen. Smith depicts much of the Baffin Land Cur- 

 rent being deflected into Hudson Strait both north 

 and south of Resolution Island. He also shows a 

 large outpouring from Hudson Strait just north of 

 Cape Chidley. The area outlined in figure 2 

 could be tagged as the "birthplace" of the Labra- 

 dor Current. Smith (1937) points out that in this 

 area three water masses join to form the south- 

 ward flowing Labrador Current which can be fol- 

 lowed down to the southern tip of the Grand 

 Banks of Newfoundland. He envisioned the Baf- 

 fin Current, from the north, joining and mixing 



with both the Hudson Strait outflowing and the 

 recurved West Greenland Current, resulting in 

 the formation of the characteristic Labrador 

 Current. This joining of the water masses ac- 

 counted for the two distinct bands or filaments of 

 the current; an inshore portion, cold and low in 

 salinity, and an ofl'shore portion of warmer more 

 highly saline water moving swiftly along the shelf 

 break. 



Smith postulated the circulation in and out of 

 Hudson Strait from iceberg and sea ice observa- 

 tions. He noted the lines of icebergs moving into 

 the strait on the northern side and iceberg move- 

 ment out of the strait along the southern limits, 

 off Cape Chidley. He also noted the rather diffuse 

 movement of the icebergs to the east of Resolu- 

 tion Island indicating a definite weakening of the 

 southward flow in that area. This information 

 was supported by many oceanographic stations to 

 the east of Resolution Island, but only four sta- 

 tions across the entrance to Hudson Strait. These 

 four stations were insufficient to describe the prop- 

 erty distribution and did not permit any detailed 

 examination of the quantitative transport and 

 exchange through the strait. 



No data was obtained by Smith concerning the 

 water exchange just north of Resolution Island. 

 His data north of this area, at the latitude of Loks 

 Land, shows that the Baffin Land Current nar- 

 rows, accelerates and at least in part appears to 

 turn into Hudson Strait through Gabriel Strait. 



Velocity values calculated by Smith show a 

 much stronger current flowing south of Hudson 

 Strait than was found to the north. This acceler- 

 ation was attributed to both the Hudson Strait 

 discharge and the convergence of the West Green- 

 land Current. Smith also speculates that the land 

 drainage from Hudson Bay Basin alone indicates 

 that the discharge through Hudson Strait 

 probably exceeds the inflow. 



Campbell (1958) presented the most compre- 

 hensive study to date of the circulation in Hudson 

 Bay, Fox Basin, and Hudson Strait. It was quan- 



