ship iceberg reports received by 

 International Ice Patrol 

 throughout the IIP area tor any 

 given year, while "sightings south 

 of 48°N" is the total number of 

 sightings south of 48°N from all 

 sources recorded as individual 

 icebergs at IIP. Icebergs 

 estimated south of 48°N are the 

 total number determined by the 

 International Ice Patrol to have 

 actually passed south of 48°N 

 during the season and reported 

 in the annual Ice Bulletin. 



There is an abrupt change in 

 the iceberg sighting ratio in 1970, 

 which could be attributed to the 

 disestablishment of Coast Guard 

 Radio Station Argentia in 1969. 

 Since 1970, the International Ice 

 Patrol has broadcast daily ice 

 bulletins and facsimile charts to 

 ships from Coast Guard 

 Communications Station Boston, 

 but has no direct communications 

 with vessels transitting the Grand 

 Banks. This lack of direct contact 

 is believed to be the cause of the 

 significant decrease in the 

 number of SST reports received 

 by the International Ice Patrol. 

 Sea surface temperature reports 

 decreased by a factor of 1 4 in the 

 mean annual number between 

 the two periods. Therefore, 

 these two periods will be treated 

 independently in this analysis. 



Table C-2 also shows that the 

 previous record year of 1972 still 

 holds the record as the most 

 severe iceberg year on record if 

 the iceberg sighting ratio is used 

 as the evaluating criterion. Using 

 this criterion, 1984 is 

 unquestionably a severe iceberg 

 year, but not as severe as 1 972. 



Table C-2 Icebergs South of 48° N 

 vs. Iceberg Sighting Ratio 



South of 48 °N Iceberg 



Icebergs Sightings, Ship Iceberg SST Sighting Ratio % 

 Year Estimated All Sources Reports Reports (Berg RPT/SST) 



1960 

 1961 

 1962 

 1963 

 1964 

 1965 

 1966 

 1967 

 1968 

 1969 

 1970 

 1971 

 1972 

 1973 

 1974 

 1975 

 1976 

 1977 

 1978 

 1979 

 1980 

 1981 

 1982 

 1983 

 1984 



253 



117 



120 



25 



369 



76 







441 



226 



57 



85 



73 



1584 



850 



682 



101 



151 



22 



75 



152 



24 



63 



188 



1348 



2202 



1538 



1286 



1072 



163 



3712 



277 



13 



1448 



719 



171 



324 



222 



3978 



2980 



3355 



331 



454 



84 



341 



168 



3 



26 



70 



620 



1106 



1008 

 928 



1077 

 251 



1362 

 227 

 51 

 524 

 384 

 139 

 439 

 162 



1151 



842 



540 



197 



312 



316 



399 



183 



40 



39 



92 



148 



586 



7436 



8342 



7916 



4633 



9147 



6347 



1592 



3194 



2271 



1985 



1014 



159 



432 



381 



215 



260 



297 



257 



478 



397 



215 



302 



434 



334 



353 



13.6 



11.1 



13.6 



5.4 



14.9 



3.6 



3.2 



16.4 



16.9 



7.0 



43.3 



101.9 



614.0 



191.4 



179.5 



77.9 



59.3 



117.1 



68.4 



46.6 



34.8 



17.4 



21.2 



44.3 



166.0 



Although the 1 983 number of 

 1 348 icebergs south of 48°N 

 makes it appear as a very severe 

 year, the iceberg sighting ratio 

 suggests that it is a light year. 

 Comparison to 1 975, the median 

 year with respect to icebergs 

 south of 48°N, indicates that 

 1 983 would have fewer icebergs 

 south of 48°N than that year and 

 that 1 984 would have more. 



Figures C-1 and C-2 show 

 plots of the iceberg sighting ratio 

 versus icebergs south of 48°N for 

 the periods 1960 through 1969 

 and 1 970 through 1 982 and the 

 linear regression fits of those 

 data. In Figure C-2, the iceberg 

 sighting ratio has been adjusted 

 by removing iceberg sighting and 

 SST reports received from Coast 



Guard vessels from the data. 

 Coast Guard vessels, when 

 deployed in the IIP area, typically 

 contribute a significant number of 

 iceberg and SST reports to IIP. 

 They do not operate within the 

 normal traffic pattern described 

 above, often actively search for 

 icebergs and have operational 

 requirements to submit regular 

 SST reports, all of which might 

 bias the Coast Guard component 

 of the iceberg sighting ratio. The 

 number of reports contributed by 

 individual vessels, including 

 Coast Guard vessels, was not 

 recorded in the International Ice 

 Patrol Bulletin priorto 1972 so 

 this adjustment could not be 

 made to eadier data. Using the 

 regression fit shown and the 



72 



