aground north of the 50° N. near the coast. The 6-8 December 

 northern survey included the east coasts of northern Newfoundland 

 and Labrador. See figure 65. The pack ice extended to a southern 

 limit near Cape Chidley on 6 December, although there were sporadic 

 formations of slush ice close along the coast south from Oape Chidley 

 to South Wolf Island. The number of bergs south of Cape Chidley 

 increased from 27 on 1 November to 41 on 6 December, but deteriora- 

 tion nevertheless had continued . 



NORMAL ISOTHERM CHARTS FOR THE GRAND BANKS AND 



VICINITY 



Several factors are involved in the relative severity or lightness of 

 the Grand Banks iceberg season. There can be little disagreement 

 that the key element is the available supply of bergs favorably located 

 upstream of the Grand Banks in the Labrador Current just prior 

 to the ice season. Once the available berg supply has been established, 

 the environment into which icebergs drift as they reach the Grand 

 Banks becomes a most important factor. What happens to the berg 

 supply, where it goes, and how long it lasts depend directly on its 

 environment including the water circulation, wind direction and force, 

 sea ice conditions, water temperature, and bottom topography. The 

 existing environment on the Grand Banks and vicinity is influenced 

 or patterned to a large degree by the recent and existing climajfe in 

 the area. The winter climate in Baffin Bay, Davis Strait, and the 

 Labrador east coast, as it affects the strength of the Labrador Current 

 and the heat transported by it in the spring months to the Grand 

 Banks, is undoubtedly an important factor. The volume, heat trans- 

 port, and strength, of the Gulf Stream near the Grand Banks is 

 another element that plays an important part in determining the 

 overall berg environment on the Grand Banks and vicinity. 



The environment on the Grand Banks and vicinity can be reason- 

 ably determined. Meteorological conditions including air tempera- 

 tures and wind speed and direction over the Grand Banks are 

 continually monitored. The wind is an important force in moving 

 ice directly by acting on the exposed portion of the berg and indirectly 

 by setting up wind current and thus contributing to the water circu- 

 lation. Wind is also important as a destructive force by setting up 

 wind waves which are erosive to ice. During the ice season, oceano- 

 graphic surveys are conducted in key areas by the oceanographic 

 vessel. Water circulation at the surface due to geostrophic current 

 is determined and water temperatures are taken at the surface and 

 to depths approaching the bottom. Nmnerous sea surface tempera- 

 tures and weather reports are received from shipping and plotted 

 during the ice season ; thus^ enabling the construction of a bimonthly 

 isotherm chart covering the entire area of responsibility. 



34 



