9. Four oceanographic surveys were conducted bet ween I April and 

 26 June for the purpose of mapping ocean currents affecting the 

 drift of icebergs and to collect scientific data. 



10. Ice conditions necessitated that Extra Southern Track "A" of 

 the North Atlantic Lane Routes be placed into effect L3 May- 

 3 June. All other track shifts became automatic on scheduled 

 dates. 



11. A series of experiments of iceberg demolition by bombing bergs 

 with high temperature incendiary bombs was conducted 3 10 

 June. 



12. A program for the evaluation of radar performance in the de- 

 tection of icebergs and growlers was conducted throughout the 

 season. 



The various aspects of the above summary are dealt with in greater detail 

 by the later sections of this Bulletin. 



Pre-season aerial ice observation in January and February indicated 

 light iceberg conditions. None were sighted during these months south of 

 the Strait of Belle Isle. Newfoundland, however, was experiencing its 

 worst winter in many years and local sea ice severely hampered coastwise 

 shipping. No effective transatlantic tracks were menaced by this ice or 

 any other field ice during the year, although ships attempting to use the 

 Cape Race Track "F" during its period of non-scheduled use (1 Dec. L5 

 May) often found it necessary to divert southward from course to avoid 

 pack ice over the northern slope of the Grand Banks. 



Winter severity extended over the Canadian Maritime Provinces and 

 the Gulf of St. Lawrence found itself in the grip of a notably heavy ice 

 season which had closed shipping at the middle of December 1958. By 

 mid-January ice was reported to be drifting seaward through Cabot 

 Strait and reached an extreme seaward limit at the end of February when 

 ice fields extended from near Sable Island on the south to St. Pierre in the 

 east. A more detailed account of the Gulf of St. Lawrence ice conditions 

 is contained within the sections discussing monthly ice conditions. On 

 I March the Meteorological Branch of the Canadian Department of 

 Transport commenced its "Aerial Ice Reconnaissance and Ice Advisory 

 Services of the Gulf of St. Lawrence and Adjacent Areas." This splendid 

 service which provides ice bulletins, forecasts and track routing in sup- 

 port of shipping bound for Gulf and River St. Lawrence ports continued 

 until 7 May when the ice threat in the Gulf had ended. Special arrange- 

 ments with the Canadian Ice Central at Halifax facilitated the rapid 

 exchange of pertinent ice information to provide the most widespread 

 service possible to shipping. The Ice Information Officer at Halifax was 

 Capt. Angus Brown, Canadian Department of Transport, and the 

 Officer-in-Charge of Ice Forecasting was Lt. Comdr. W. E. Markham, 



rcm;. 



At the beginning of March Newfoundland and Labrador pack ice in 

 its annua] southward drift had encroached on the northern slope of the 



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