the period November-June. Also, some bergs from north of Cape 

 Dyer will make it. Under very favorable conditions, the survival 

 percentage might increase to 40 percent, with a sizable number 

 from north of Cape Dyer. Considerably more data must be accumu- 

 lated over the years to obtain accurate survival percentages. Of 

 course, the surveys must take into account the individual berg sizes 

 and the forecast survival must be based both on the berg count and berg 

 sizes. An estimated 50 percent of the bergs along the Labrador coast 

 in mid-January of 1963 drifted south of 48° N., with an estimated 90 

 percent drifting south of 49° N. These percentages may be higher 

 than normal due to very favorable meteorological conditions during 

 March for berg drift south and berg survival and a minimum of perma- 

 nent stranding. An estimated 18 percent of the bergs south of Cape 

 Chidley, Labrador, in mid-March 1963 drifted south of 48° N. This 

 is believed somewhat less than normal due to generally unfavorable 

 meteorological conditions from mid-March through May. Perhaps 

 closer to 30 percent of bergs south of Cape Chidley in mid-March 

 survive to drift south of 48° N. under normal meteorological conditions 

 from mid -March to June. 



9. All available evidence indicates that almost all of the berg crop 

 drifts south by Cape Dyer. Very few bergs are supplied from West 

 Greenland to the Baffin Land Current south of Davis Strait. Berg- 

 producing glaciers are almost nonexistent south of Disko Bay, West 

 Greenland. Many bergs of East Greenland origin do drift west around 

 Cape Farewell and then north in the West Greenland Current, but it 

 is concluded that very few ever reach the Labrador Current. 



10. A reasonable forecast of the severity of the next Grand Banks 

 iceberg season can be made in late autumn by determining the available 

 supply of bergs upstream. In early November the Grand Banks berg 

 potential will normally be located from Cape Chidley, Labrador, to 

 Cape Christian, Baffin Island. By early December the berg potential 

 will have progressed to near 57° N. along the Labrador coast and will 

 include the area along the Continental Shelf north to about Cape Dyer. 

 Assuming normal meteorological and oceanographic conditions for the 

 next 6 or 7 months, about 25 percent of the berg potential can be fore- 

 cast to drift south of 48° N. Thus a count of about 1,500 bergs would 

 indicate a normal Grand Banks iceberg year. A count of over 2,500 

 bergs would indicate a heavy year, and a count less than 1,000 a light 

 year. The survivor percentage used for the forecast should be preju- 

 diced by berg sizes. Bergs should be classified small (<50' height, 

 <200' length); medium (50'-150' height, 200'-500' length), large 

 (150'-250' height, >500' length); and very large (>250' height). 

 For tabular types the following sizes should be used: small (<20' 

 height, <300' length); medium (20'-50' height, 300'-600' length); 

 and large (>50' height, >600' length). The forecast can be modified 



41 



731-298 O - 64 - 4 



