Table A-l. — Iceberg Drift Data from IIP-2-74 Cruise 



Vector Vector Vector Vector *Averape Ratio of the 



\\ei.i"eJ \vcraped \veraped Averaped An^le of the Average Drift 



Pi' i ft Drift Kind Kind' Drift to the Speed of the 



Speed nirection Speed Direction Ripht of the Average Kind 



IkTs.i (°T) (KTS.l Minus 18(1° hind Speed 



t°Tl f°) 



Jvpe 



Size (meters) 



■ or 

 riBS. 



Date/Tine 

 ( I oca 1 1 

 Observed 

 ( lunc 1074] 



r rom To 



'tedium 

 Pinnacle 

 2 1N122 



l.arpc 



I'mnaclc 



37x137 



**Mcd illPl 



Drvdock 

 46x101 



Small 

 Domed 

 6x3(1 



Small 



Tabular 

 18x61 



Vcrv Lar^c 

 lloublc 

 Pinnacle 

 S.ix265 



x s.d. x s.d. 



20/0911 23/1007 n. 



:n/no-,5 26/0348 0.4 



8 24/1342 28/2300 0.0 



I 16(P 26/084-1 n.n 



24/ls2> 26/0800 (1.3 



2b/l"nn 20/11133 



is: 



1S1 



13.0 035 -021 t 065 .016 t .006 



11.2 nil 002 t 081 .041 ± .033 



12.1 134 060 l (1.18 .071 ± .031 



ins 086 ♦ 013 .OSS ± .012 



12.4 105 086 ± 018 .070 ± .015 



13.5 



OSS 



*Neqative values indicate a drift angle to the left of the wind 

 •Iceberq >3 calved into two nieces between 38/0100 and 28/0028 (local) 



.085 t .025 



ICEBERG DRIFT RESULTS 



The drift of the six icebergs was determined 

 for the time between observations as often as 

 possible during the period 20/0911 Local to 29/ 

 0138 Local June 1974. The icebergs were tracked 

 from 1.6 to 4.8 days. Wind velocities were logged 

 hourly by the CGC EVERGREEN'S bridge 

 watch. All icebergs tracked during the experi- 

 ment were found in the area bounded by 44-30N 

 to 47-30N and 47-OOW to 48-30W. Air tempera- 

 tures during the iceberg tagging project ranged 

 from 3.9°C to 9.4°C with an average about 6.4°C. 

 The surface sea water temperature for the same 

 period ranged from 1.1°C to 10.6°C with an aver- 

 age about 3.9 °C. The weather was predomi- 

 nantly overcast with fog and visibility typically 

 less than 100 yards for the entire drift survey. 

 The sea state was moderate to calm. The data 

 from observations taken during the second Ice 

 Patrol cruise of 1974 are summarized in Table 

 A-l. 



The vector averaged drift for the bergs varied 

 from 0.2 kts for iceberg #1 to 1.1 kts for iceberg 

 #6. The average drift speed to average wind 

 speed ratio ranged from 0.16 to 0.85. An ex- 

 pendable surface current probe was deployed in 

 the van of iceberg #6 which measured a surface 



current of 1.23 kts setting at 193°T. This com- 

 pared to the iceberg drift of 1.1 kts at 212°T. 

 The wind was 13.5 kts from 319°T. 



The drift angle with respect to the wind direc- 

 tion had a large standard deviation which was 

 ±18° to ±81°. Furthermore, a number of obser- 

 vations (14%) indicated drift angles to the left 

 of the wind. Ettle (1974) had iceberg drift data 

 from past Ice Patrol cruises that gave a range 

 of standard deviations for drift angles of ±54° 

 to ±104°. 



DISCUSSION OF ICEBERG DRIFT 



Iceberg drift studies have always been handi- 

 capped by a lack of precise navigation and cur- 

 rent information. In this study, satellite naviga- 

 tion was used for the first time, but since tagging 

 the iceberg was of primary interest few current 

 measurements were taken. Budinger (1960) put 

 together a drift experiment that used current 

 measurements, but was plagued by the poor pre- 

 cision of the geomagnetic electro-kinetograph 

 (GEK) surface current measurements and by 

 inadequate navigation. Ettle (1974), in his an- 

 alysis, did not treat the currents in the area of 

 the drifting iceberg. Therefore, his results do 

 not separate out the effect of the wind. In order 



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