The second segment of the second cruise (fig. 

 12) shows that the Labrador Current was un- 

 usually strong at 44. 5N, 48.7W. Although com- 

 parison with the normal chart for May shows 

 that the dynamic heights on the Grank Banks 

 were abnormally high, they were very little 

 higher than those observed on the previous sur- 

 vey six days earlier. During this six day period, 

 the dynamic trough deepened by more than ten 

 dynamic centimeters. Comparison of stations 

 10730 (23 May) and 10749 (29 May), which 

 were both located in the dynamic trough and 

 were separated by 5 miles distance and six days 

 time, shows that 42% of this decrease in dy- 

 namic height occurred between 50 and 200 m. 

 (table I). Comparison of the T-S curves for 

 these two stations (fig. 13) shows the presence 

 of colder (2°C.) and saltier (0.25%o) water from 

 50 m. to about 400 m. on 29 May ; both resulted 

 in increased density and a lower dynamic height. 

 (See discussion of standard section A3 time se- 

 ries for further description.) Below 400 meters, 

 there was little change. 



Topography Relative to 3,000 Decibars 



On 26 stations of the second cruise, data were 

 obtained to a depth of 3000 m. Defant's method 

 of finding the surface of no motion (Defant, 

 1961) was applied to nine pairs of stations. In 

 seven cases, there was little or no motion below 

 depths ranging from 500 to 2500 m. ; in the re- 

 maining two cases, there was no discernible 

 surface of no motion from the sea surface to 

 3000 m. Consequently, 3000 decibars was used 

 as a reference surface. 



The same major features are evident on the 

 dynamic topography relative to either the 3000 



(fig. 14) or the 1000 (fig. 10) decibar reference 

 surface. On the topography relative to the 3000 

 decibar surface, the features are more intense 

 and the isopleths show greater curvature. The 

 general agreement indicates that the use of a 

 1000 decibar reference surface is equally satis- 

 factory in this region. 



STANDARD SECTION TIME SERIES 



Standard section A2 was occupied four times 

 (three times by CGC EVERGREEN and once 

 by CGC ABSECON) in the spring of 1970. 

 Standard section A3 was occupied three times 

 during this period. The data from these occupa- 

 tions have been analyzed in an attempt to detect 

 and explain changes with time at these sections. 



Standard Section A2 



The four occupations revealed little change 

 in dynamic topography (<5 dynamic centime- 

 ters) along the slope of the Grand Banks (fig. 

 15). The increased dynamic heights over Flem- 

 ish Cap (apex of angle) observed by CGC AB- 

 SECON (11 and 12 April) were due in part to 

 advection of warmer (about 0.2"'C.) and fresher 

 (about 0.4%o) water between 100 and 200 m. 

 (figs. 41 and 42, NODC Ref. No. 31-1633). 



The changes in volume transport with time at 

 standard section A2 (fig. 16 and table II) were 

 about the same as previous observations in 1967 

 (Morgan, 1969) and 1968 (Andersen and Moy- 

 nihan, 1971). Although the total southward 

 transport increased significantly as the season 

 progressed, the southward transport due to the 

 cold core of the Labrador Current (<2.0°C. and 

 <34.3%o) did not (fig. 16 and table II). 



