surface prepared by Soule, 1964 (figs. 1 and 2). 

 These charts are based on 22 years of data 

 with equal weight being given to each year 

 represented. Broken-line contours have been 

 used in areas where the data base is 6 years or 

 less. The charts show the Labrador Current 

 flowing south between the 100 fathom and 

 1,000 fathom contours on the eastern slope of 

 the Grand Banks. To the east of the Labrador 

 Current is a dynamic trough consisting of 

 water of low specific volume resulting from the 

 mixing of Labrador Current water and North 

 Atlantic Current water. The Labrador Current 

 flows south on the western side of the dynamic 

 trough and the North Atlantic Current flows 

 north on the eastern side of the trough. A pair 

 of meanders present at about 41 °N, 50° W and 

 43°N, 46°W are part of the North Atlantic 

 Current. 



RESULTS OF THE 1969 CRUISES 



North Atlantic Current Meander 



During the first survey of the season, the 

 meander of the North Atlantic Current was 

 farther to the northwest and followed a more 

 tightly curved path than normal. This may be 

 seen by comparison of the positions of the 971.0, 

 971.1, and 971.2 dynamic-meter contours ob- 

 served during the first survey in April (fig. 3), 

 with the positions of these contours on the 

 April normal dynamic topography chart (fig. 

 1). During subsequent surveys of the 1969 

 season, the meander moved progressively to the 

 northwest (figs. 4, 5, and 6). 



Tail of the Banks 



The dynamic topography south of the Tail 

 of the Banks was particularly complex during 

 the 1969 Ice Patrol season. The survey during 

 6-7 April (fig. 3) showed a westward flow 

 around the Tail of the Banks, south of which 

 lay an unusually wide (111 km) dynamic 

 trough. Looking southward from the trough, 

 the dynamic topography indicated a fairly 

 narrow but intense flow to the east, then south 

 of that, a flow to the west. During the 26-27 

 May occupation of A4 (fig. 4), the dynamic 

 trough was markedly narrower (18 km). 

 Narrow eastward and westward flows were 

 evidenced south of the trough, with a wide and 



intense eastward flow present on the southern 

 portion of the section. During the final sui-vey 

 of A4 on 3 and 4 June (fig. 6), the trough was 

 nonexistent, and an eastward transport was 

 found on the slope of the Tail of the Banks. 



Slope Water Current 



The occupation of standard section A4 dur- 

 ing 3-4 June 1969, which extended further 

 south than the usual Ice Patrol section, showed 

 Slope Water Current (Slope Water is defined 

 as water which is slightly less saline at all 

 temperatures than Gulf Stream or North At- 

 lantic Drift Water) and the Gulf Stream as 

 separate currents crossing 50°20'W longitude 

 north of 42°30'N and south of 41°30'N, respec- 

 tively. A distinct westward countercurrent was 

 found between them (fig. 26). Fuglister (1963) 

 pointed out these features based upon the "Gulf 

 Stream '60" expeditions and the past data of 

 the Ice Patrol, but left the relationship between 

 the two currents unclear. Mann (1967) sug- 

 gested that the Gulf Stream meanders north 

 and south in the vicinity of 50°W longitude 

 with a path shaped like the letter S, and por- 

 trayed the westward countercurrent as part of 

 the meander which recurves cyclonically to con- 

 tribute to the eastward transport of the Slope 

 Water Current. This had been previously 

 hypothesized by Soule, et al. (1960, 1961). 



From April to June 1969 (figs. 7, 22, 26), the 

 Slope Water Current and Gulf Stream migrated 

 northward along section A4 and appeared to 

 cause a decrease in the size of the trough be- 

 tween them and the Labrador Current (figs. 

 3, 4, 6). This northward progress of the Slope 

 Water Current also appeared to reduce the 

 westward flow of the Labrador Current on the 

 slope at the Tail of the Banks and no negative 

 temperature water was found flowing west- 

 ward during the 1969 occupations of section 

 A4. Because only the June occupation of section 

 A4 completely transected both the Slope Water 

 Current and the Gulf Stream, it is impossible to 

 compare the volume transports of these cur- 

 rents with the earlier 1969 occupations. How- 

 ever, the eastward transport of 44.3 sverdrups 

 through section A4 (above the 1,000 decibar 

 level) on the June occupation compares favor- 

 ably with previous Ice Patrol measurements 

 and those of other investigations. 



