1972 ICEBERG STUDIES 



Three icebergs were tracked by Coast Guard 

 cutters, while acting as the surface patrol vessel, 

 during the 1972 ice season. From .5 to 11 May, 

 the CGC VIGOROUS (^^T^EC-627) tracked a 

 niediuiu iceberg using celestial fixes as the pri- 

 mary means of navigation. The May 1972 

 oceanographic sui'vey (fig. 54) did not (;over the 

 area where this iceberg was drifting. However, 

 from the May normal chart (fig. 44) and the 

 May 1972 survey it is apparent that this iceberg 

 was located well into the North Atlantic Current 

 when it was being studied. This iceberg, drift- 

 ing an average of more than 30 nmi per day, was 

 predominantly effected by the North Atlantic 

 Current (fig. 56). Only during the early part 

 of the study period did the wind, which averaged 

 17 lais from 224°T (fig. 56), have any significant 

 effect on the iceberg's drift. 



CGC EVERGREEN tracked two icebergs— a 

 large tabular iceberg from 8 to 15 June and a 

 small iceberg from 9 to 13 June. Due to heavy 

 fog, Loran A, with an accuracy of 3-5 miles, was 

 used for positioning during this study. These 

 icebergs drifted around in the same general area 

 during the study period (fig. 57). These drifts 

 were in great contrast to the one in May. Dur- 

 ing this study four sets of four STD stations 

 were taken around the large iceberg. The gen- 

 eral flow of the current in this area was southerly 



(fig. 58), although not nearly as constant as in 

 the core of the Labrador Current which existed 

 farther to the north. From the iceberg drift, it 

 appears that the effect on these icebergs from the 

 southerly flowing current was to a great degree 

 offset by the effect of the wind (fig. 57), which 

 averaged 14 kns from 188°T during the large 

 iceberg study and 195°T at 19 lens during the 

 small iceberg study. 



Four expendable bathythermograph (XBT) 

 sections were conducted at two-day intervals. 

 Each section, consisting of 10 XBTS, was on a 

 constant bearing from the large iceberg ranging 

 from 10 to 500 yards from the iceberg. The 

 purpose of this experiment was to check for 

 horizontal temperature gradients, previously 

 mentioned by Kollmeyer et al, 1966, along each 

 section. However, no gradient was apparent on 

 any of these sections. 



From photographs taken around an iceberg, 

 mass determinations of that iceberg can be made. 

 It was hoped that this could be accomplished 

 several times during the drift study of the large 

 iceberg, for such a study could yield information 

 on the rate of deterioration of the iceberg. How- 

 ever, due to poor visibility, a good set of photo- 

 graphs was obtained only at the end of the drift 

 study. At that time it was determined that the 

 iceberg had a mass of approximately 3 x 10^ kgs. 



