end of the section were lower than normal. It 

 was interesting to try to determine what 

 caused the anomalously low dynamic height 

 values. They could be caused by two factors: 



1. The temperature-salinity characteristics 

 of the water located on the Grand Banks. 



2. The distribution of temperature-salinity 

 characteristics of the water just to the east 

 of the continental slope. 



It was doubtful that the temperature-salinity 

 characteristics of the water overlaying the 

 Grand Banks caused these abnormally low 

 values. This water contributed only to the sur- 

 face 50 to 100 meters of the dynamic height 

 for each station. This was an extremely small 

 depth to cause such abnormally low values. 



Consider the values given below for stations 

 located in approximately the same location : 



YEAR 



1966 



1964 



1954 



STATION 



NUMBER 9516 9517 8836 8837 5321 5322 



ANOMALY 



OF 0.061 0.048 0.065 0.066 0.081 0.080 



DYNAMIC HEIGHT 



0-50 METERS 



In each instance in a "normal" year, i.e., 

 1954 and 1964, both on the Banks and coming 

 off the Banks the surface layer had the same 

 density for equal intervals. In the abnormal 

 year, i.e., this year, an increase in density was 

 observed in the surface layer for an eastward 

 displacement. Although this water was denser 

 than normal, it was only 0.02 dynamic meters 

 less than the maximum dynamic height value 

 observed in the normal year of 1954. This 

 analysis showed that even though the surface 

 50 meters was more dense this year than in a 

 normal year this increase in density was not 

 enough to cause the anomalously low dynamic 

 height values. 



The distribution of temperature-salinity 

 characteristics just east of the continental 

 slopes must have caused the low dynamic 

 height values. This temperature-salinity dis- 

 tribution influenced the dynamic height values 

 when integration was done up the Banks. 

 Since low dynamic height values were ob- 

 served on the continental shelf, the water just 



east of the continental slope must have been 

 denser than normal. It must be emphasized 

 that this low shelf dynamic height value was 

 associated with one of the highest trough 

 dynamic height values ever observed. There- 

 fore, these low shelf values were a direct I'esult 

 of the temperature-salinity distribution im- 

 mediately adjacent to the continental shelf 

 and in this case did not indicate what the 

 trough dynamic height value should be. 



The vertical temperature and salinity struc- 

 tures observed along Standard Section 3 on 

 4-5 April 1966 were interesting. The most 

 noticeable change from the earlier occupations 

 was the intrusion of 7.0° C water at the 50- 

 150 meter level at station 9519. Water with 

 this temperature-salinity characteristic has 

 been classified as atypical. "Atypical" in this 

 case meaning it does not fit along one of 

 the predefined curves for Labrador Current, 

 Mixed, or Atlantic Current water shown in 

 Figure 25. This atypical characteristic oc- 

 curred at stations 9518 to 9522. It was over- 

 laying water with temperature-salinity 

 relationships which were common to the deep 

 water of all three water masses shown in 

 Figure 25. 



Looking at Figures 19 and 20, consider a 

 temperature-salinity curve using data obtained 

 by moving along the surface from a point mid- 

 way between stations 9518 and 9519 to a point 

 midway between 9519 and 9520 and a tempera- 

 ture-salinity curve obtained using data from 

 the surface 200 meters of station 9518. It is 

 obvious that these two temperature-salinity 

 curves will be similar since the same isohalines 

 and isotherms pass through each location. 

 Hence this was probably a region of conver- 

 gence where sinking had occurred. 



"NORMAL" TEMPERATURE, SALINITY, 

 AND DYNAMIC HEIGHT 



The extremely anomalous conditions ob- 

 served along Standard Section 3 were more 

 evident when compared to historical salinity 

 and thermal vertical structures during "nor- 

 mal" years. "Normal" years were selected 

 using : 



1. Duration and distribution of sea ice on 

 the Grand Banks 



2. The number of icebergs that drift south 

 of 48° North latitude 



