substantial departure from this 

 distribution. Recognizing these 

 similarities, IIP, in 1979, combined 

 the rrronthly mean hydrographic 

 fields and computed a single 

 mean current field (Murray, 1979) 

 for use in HP's numerical iceberg 

 drift model. 



While the monthly mean dynamic 

 topography represents the main 

 features of the circulation, the 

 averaging smooths out variations 

 that may affect the circulation. For 

 example, trajectories of satellite- 

 tracked drifting buoys released in 

 the LC (Anderson, 1983 and 

 Anderson, 1984) suggest a much 

 more complex flow pattern than 

 the mean hydrography depicts. 

 Figure C-3 summarizes the drift 

 tracks of 17 buoys, deployed by 

 IIP over a 10-year period (1976- 

 1986), that passed through the 

 study area. Although the tracks 

 show the LC clearly, the most 

 striking feature of the plot is the 

 variability in the flow field. A 

 further indication of variability in 

 the area is shown by the map of 

 standard deviation of dynamic 

 height of the individual hydro- 

 graphic surveys from the April 

 mean (Figure C-4). The pattern of 

 fluctuations in the standard 

 deviation suggests that meanders 

 and eddies of the NAC are major 

 features, particularly in the eastern 

 and southern areas where the 

 standard deviation reaches 15 

 dyn-cm. 



Little is known about the sizes and 

 frequencies of NAC meanders or 

 eddies in the study area, primarily 

 because fog and clouds fre- 



54 



Figure C-2 Average dynamic topography for the month of April 

 (from Scobie and Schuitz, 1976). 



50«N 



48« 



46" 



44« 



42»N 



53»W 5r 49» 47* 



1 1 — 



45*W 



I I 1 r 



1 — r 



1000 m«f«rt 



± 



_L 



9JI.2 

 J L_ 



_L 



_L 



50«N 



48* 



46* 



44. 



42»N 



53»W 51' 49* 47* 45»W 



quently prevent mapping of the 

 ocean's features by satellite 

 infrared (IR) imagery. Using the 

 sparse IR data available, Williams 

 (1985) studied the eddy population 

 east of the Grand Banks. He 

 found that eddies are frequently 

 seen near the Newfoundland 

 Seamounts and Ridge. He 

 suggested that eddy generation is 

 caused by the rapid changes in 

 Ixjttom topography, but there were 



insufficient data to form a com- 

 plete history of an eddy. 



Although IR mapping is limited by 

 fog and clouds, satellite and 

 airtxjrne imaging radars, particu- 

 larly the synthetic aperture radar 

 (SAR) camed aboard SEASAT, 

 are capable of all-weather detec- 

 tion of oceanic features such as 

 fronts and internal waves (Fu and 

 Holt, 1982; Hayes.1981). Using 



