Although the number of icebergs that pass south of 48°N during a year plays a large role in the overall 

 NSSI value, the additional factors of LAKI area and LOS can cause different relative rankings among 

 season severities. Take the three most severe years by iceberg count and NSSI. By iceberg count alone, 

 the most severe years are 1984. 1991. then 1994. Using the NSSI. the most severe year is 1991 followed 

 by 1984. then 1993. thus reversing the positions of 1984 and 1991 as the year considered to be the worst 

 iceberg year in IIP"s history. Table 1 shows a detailed comparison between the 1984 and 1991 iceberg 

 seasons. It shows the contributions of each of the three factors (LAKI area. LOS and iceberg count) to the 

 NSSI and the ranking in each of the areas. The 1991 ice season had an average LAKI area of 151.234 nm" 

 (Figure 3) with a season lasting 183 days. Both of these factors contributed to its place as the most severe 

 iceberg season during the study period severity of the 1991 season. In comparison, the year 1984 had 

 2.202 icebergs south of 48°N. an average LAKI area of 125,802 nm" (Figure 4) and a season lasting 170 

 days. 



Table I. Differences in NSSI ratings between 1984 and 1991 



Figures 3 and 4 show how the LAKI area changed throughout the 1991 and 1984 iceberg seasons, 

 respectively. In the case of 1991. the LAKI area was near 200.000 nm' for the period from early April 

 through mid July. The LAKI area distribution for 1984 was close to the classic normal distribution with a 

 peak in late May. Using the iceberg count alone, this effect is not considered, thus the severity of the 

 season from the standpoint of the mariner was not represented. From the mariner's viewpoint, the 1991 

 iceberg season was somewhat more severe than 1984 because the iceberg danger area was very large for a 

 greater length of time, despite the fact that in 1984 there were over 200 more icebergs during the season. 



300000 

 250000 

 200000 

 150000 

 1 00000 

 50000 



I • 



25-Dec 13-Feb 4-Apr 24-May 13-Jul 1-Sep 21-Oct 



Date 



Figures. 1991 LAKI Area 



59 



