Treatment of Data 



Numerical integration of the anomaly of 

 specific volume, based on the temperature and 

 salinity distribution obtained at each station, 

 was accomplished on shipboard using a Digital 

 Equipment Corp. PDP-5 computer. All deep 

 sea reversing thermometers were corrected by 

 the computer thus eliminating all hand com- 

 putations. Actual observations were used as 

 data inputs for the computation of dynamic 

 heights. No scaled data for standard depths, 

 other than the 1,000-meter reference level, were 

 used in the computations. The programs used 

 are described by O'Hagan (1964). 



Daily transmissions of the computed dynamic 

 heights for each station occupied, along with the 

 temperatiu-e distribution down to 150 meters, 

 were made to Commander, International Ice 

 Patrol, Argentia, Newfoimdland. This allowed 

 the immediate construction and use of portions of 

 the sea surface topography charts for iceberg 

 drift prediction. 



Chart Discussion 



The first survey chart, obtained during 30 March 

 to 7 April 1965, figure 2A, shows the Labrador 

 Current flowing south along the 100-fathom curve. 

 At the Tail-of-the-Banks, part of the current 

 flows west and another portion recurves to the 

 east forming a pool of quiet water. Some fila- 

 ments in this area turn and flow northward con- 

 tributing to the mixed water area of the trough. 

 This trough area is the region of current reversal 

 where the Labrador Current floM's south on the 

 western side and the Atlantic CiuTent flows north 

 on the eastern side. The water in this region has 

 a low specific volume. It is made up of a mixture 

 of Labrador Current water and Atlantic Current 

 water giving a water mass characteristic between 

 the two as seen in the T-S curve of figure 6A. 

 This mixture produces a water mass of a character- 

 istically low dynamic stand compared to the much 

 higher topography towards the Banks and towards 

 the Atlantic Current to the east. For this reason 

 it is referred to as the low or trough of the circu- 

 lation pattern. This is a characteristic feature 

 generally found ui the vicinity of tlie 1,000-fathom 

 curve and sometimes extends as far south as the 

 Tail-of-the-Banks. 



The meanders of the Atlantic Current outlhie 

 the pool of water formed to the east of the tail. 

 This appears to be supplied by the water oi the 



Labrador Current spilling into the area and is a 

 normal circulation feature found in past years. 



An area of contour uncertainty exists in the 

 northeast part of the current chart, figure 2A, 

 at 46°30' N., 48°00' W. Insufficient data in the 

 area prevents the determination of flow direction 

 from dynamic topography alone and will be 

 discussed ui the following section in isentropic 

 analysis. 



The check survey chart, obtained during 11-12 

 April 1965, figure SA, represents an interesting 

 reoccupation of section U within 9 days ol the 

 first occupation. The 971.1 dynamic meter 

 streamline, nonexistent in that area on the first 

 survey, was found. In addition, the 971.0 dynamic 

 meter streamline was found to have shifted east 

 by about 30 miles, while the trough feature shifted 

 eastward less than 10 miles resulting in a swifter 

 flowing Labrador Current. 



The second survey, 7-10 May 1965, figure 4A, 

 shows the Labrador Current tracking along the 

 100-fathom curve with some lateral filaments 

 spilling onto the Banks as it turns to the south. 

 The 971.0 and 970.9 dynamic meter streamlines 

 are in much the same position, passing through 

 section F, as on the first survey. The 971.1 

 dynamic meter streamline was not observed, 

 however, contours up to 971.08 dynamic meters ( 

 are drawn and indicate that lighter water was 

 further up on the Banks. This was also reflected 

 in figure 3 A, the check survey, where 971.1 

 dynamic meter streamline appeared well up on 

 the Banks in section U. 



The third survey, 19-25 May 1965, figure 5A, 

 showed the Labrador Current as a strong uniform 

 flow along the 100-fathom curve from 47°30' N. 

 to 43°00' N. The characteristic trough was 

 greatly elongated and the pool of quiet water 

 found during the first survey was missing. The 

 streamlines of the Atlantic Current tended to 

 turn north at the Tail-of-the-Banks \nthout 

 describing any low velocity or stationary pool of 

 A\ater. A cyclonic eddy occurred to the east at 

 44°00' N., 46°00' W. This eddy or gyre ex- 

 hibited water cliaracteristics similar to those 

 found in the pt>ol of water, described by the first 

 survey data, at the Tail-of-the-Banks. The eddy 

 appeared to be the residt of the pinching off of tlie 

 pool and its subsequent movement to the north- 

 east. This pinching ofi" of an eddy is a phennom- 

 ena exhibited by Gulf Stream filaments and de- 

 scribed by Fuglister et al. (19-51). Insufficient 



