topography to the east was relatively flat and 

 increasing slowly. The rate of increase was 

 large enough however to produce a dynamic 

 height of 971.028 dynamic meters at station 

 36. This was the largest value observed on the 

 section and was also an increase over that ob- 

 served during the 14-15 February occupation. 



The vertical temperature and salinity sec- 

 tions show the 4.0° C isotherm and the 

 34.0%o isohaline well to the west. Again, the 

 expected cold core was not observed. This oc- 

 cupation occurred close enough to the regular 

 International Ice Patrol occupations to con- 

 sider the lack of negative temperature as an 

 anomalous situation. Again a great deal of 

 subjective contouring was used to determine 

 the positions of the isotherms and isohalines 

 just to the east of the continental slope. The 

 southward moving water had become slightly 

 colder and more saline. The minimum temper- 

 ature and salinity occurred at the bottom and 

 the top of station 26, respectively they were 

 1.00° C and 33.56%o. Station 26 was essentially 

 isohaline and the minimum salinity was no 

 doubt due to some surface effect. Again a 

 small 5.0° C core was observed, but this time 

 it was in the northward flow. The temperature 

 to the east had increased to 9.0° C and salini- 

 ties to 34.90%o, indicating that this was North 

 Atlantic Current water. However, station 36 

 had Mixed Water characteristics indicating 

 that only a filament of the North Atlantic Cur- 

 rent had been crossed. 



In summary, items that should be noted 

 about this occupation of Standard Section 3 

 are: 



1. The lack of water with a temperature less 

 than 0.0° C in the core of the Labrador Cur- 

 rent. This can be considered to be a definite 

 anomaly because this occupation occurred less 

 than two weeks prior to many occupations of 

 this section in earlier years when tempera- 

 tures less than —1.0° C were observed. As 

 will be shown later, no 0.0° C water was ob- 

 served during the occupation of Standard Sec- 

 tion 2, implying but not proving that tempera- 

 tures observed on Standard Section 3 were 

 anomalously warm. 



2. The failure of this section to indicate the 

 North Atlantic Current. Apparently this sec- 

 tion crossed a small, cool, filament of the North 



Atlantic Current but did not intersect the 

 main portion of the current on the surface. 

 This was indicated by the temperature-salinity 

 characteristics observed at station 36. 



CGC EVERGREEN 4-5 APRIL 1966 

 OCCUPATION OF STANDARD SECTION 3 



The CGC EVERGREEN, as a part of the 

 International Ice Patrol, conducted a calibra- 

 tion survey on the Grand Banks commencing 

 on 2 April 1966. This included the northern 

 part of Standard Section 4, Standard Section 

 3, and the east-west portion of Section 2. 



A chart of the dynamic topography for 

 these three sections is shown in Figure 1. Fig- 

 ures 17 through 22 are the vertical tempera- 

 ture and salinity distributions along these 

 sections. 



A comparison of the bottom profiles ob- 

 tained by the CGC EVERGREEN and CGC 

 HUMBOLDT and the CGC DUANE indicates 

 that both CGC DUANE and CGC EVER- 

 GREEN probably were at the same loca- 

 tion when they commenced the occupation of 

 Standard Section 3. Figure 23 shows the sur- 

 face dynamic heights values obtained along 

 Standard Section 3 by the CGC EVER- 

 GREEN. 



Possibly the most dramatic change observed 

 was the diminishing of dynamic height values 

 of the Banks stations and filling of the trough, 

 causing a virtual elimination of any surface 

 manifestation of the Labrador Current. To the 

 east the slope of the dynamic topography in- 

 creased radically between station 9523 and 

 9525 indicating an extremely large flow to the 

 north. Compared with the surface dynamic 

 topography obtained from the normal charts 

 for April (Figure 24), the anomalous condi- 

 tions were very evident. 



The maximum dynamic height value of 

 971.02 dynamic meters occurred at station 

 9517 and the minimum dynamic height value 

 of 970.948 occurred at station 9523. There was 

 a secondary minimum of 970.971 dynamic 

 meters at station 9518 indicating that the rela- 

 tively narrow trough separating the Labrador 

 Current and the North Atlantic Current had 

 broadened to become the most dominant fea- 

 ture of the profile. 



A comparison of Figures 23 and 24 showed 

 that the dynamic height values on the western 



8 



