lifetime. Most icebergs which were resighted 

 were updated once. In 1 993, the probability of 

 an iceberg being resighted had increased to 

 43.3%. As in 1992, most icebergs resighted 

 were updated once. 20.8% of the icebergs 

 were resighted more than once in 1 993, com- 

 pared with 12.3% the year before. A single 

 iceberg was resighted 1 3 times in 1 993 but this 

 was an anomaly due to its location in an area 

 of weak currents along the Newfoundland 

 shore. Its position was such that it was repeat- 

 edly detected by Atlantic Airways flights. 



The mean distance change of the ice- 

 berg position on resight in 1992 was 24.1 nm. 

 The distance change was less than half (1 0.4 

 nm) in 1993. The decreased distance was 

 most apparent along the east flank of the 

 Grand Banks: in 1992 the mean distance 

 change was approximately 25 nm, while the 

 mean was 12 nm in 1993. The high iceberg 

 density in 1 993 contributes to this decrease as 

 more icebergs on plot were available to corre- 



late with the most recent sightings. Nearerthe 

 typical limits of all known ice, the distance 

 changes were similar between years, the mean 

 being 15-25 nm. 



The latitudinal distribution of sightings 

 and resights in the two study years was also 

 investigated (Table II). The number of ice- 

 bergs added can be determined by subtract- 

 ing the number of resights from the number of 

 sightings. In 1992, sightings were more fre- 

 quently treated as new icebergs. For each 

 1992 resight there were 1.9 icebergs added. 

 With the change to the DMPS, there were 1 .2 

 icebergs added for each resight. This differ- 

 ence was most pronounced north of 49N, 

 where few resights were performed in 1992. 

 Most resights occur in the area known as 

 'iceberg alley', where the Labrador current 

 flows southward along the east side of the 

 Grand Banks. 



Table II 



Sightings Relative to Resights 

 Sightings include icebergs and radar targets. 



89 



