The vertical temperature structure over the 

 Labrador continental shelf in 1966 differed 

 significantly from any observed previously. 

 The cold core, normally delineated by the 

 — 1.0° C isotherm, had degenerated into 3 

 cores. The 2.0° C isotherm intruded discontin- 

 uously over the continental shelf. This 2.0° C 

 Vi^ater was also characterized by the 34.0%o 

 isohaline. The intrusion of this comparatively 

 warm saline water was very unusual and the 

 high velocity core, just east of the continental 

 slope and delineated by the 4.0° C isotherm, 

 was also anomalous. The salinity structure 

 over the Labrador continental shelf was anom- 

 alous, indicated by the relatively fresh water 

 of less than 32.0%o being displaced by warmer, 

 more saline water. The temperature and salin- 

 ity structure observed in the Labrador Sea had 

 also changed. Two 3.5° C cores were observed 

 below 1200 meters and the 34.90%o isohaline 

 indicated that the salinity of the deep water 

 of the Labrador Sea was greater than 34.9%o. 

 Instead of the coreless structure normally ob- 

 served, the warm part of the West Greenland 

 Current was characterized by a small core 

 of water having temperatures greater than 

 5.0° C and salinities greater than 35%o. 



This occupation of Standard Section 1 in- 

 dicated that the south-flowing water was 

 warmer and saltier than normal and led im- 

 mediately to the speculation that one reason 

 for the anomalously warm temperatures ob- 

 served in the Labrador Current was the lack 

 of cold water being transported south. Al- 

 though this section was occupied in early June 

 and the anomalously warm conditions to the 

 south were observed earlier, one must still 

 wonder if the remnants of earlier conditions 

 were still not manifest along the section. 



SECTIONS A, B, and C 



Section C, Section B, and Section A were 

 designed to show the parameter distribution 

 in the water east of Newfoundland. Excluding 

 the Labrador Sea Section, these were the only 

 sections where water less than 0.0° C was 

 found. The vertical thermal and salinity struc- 

 ture are shown in Figure 57 through 62. Sec- 

 tion C and Section B both showed similar 

 characteristic intrusions of large amounts of 

 comparatively warm water (3.5° C to 4.0° C) 

 well up onto the continental shelf. Again one 



was forced to speculate if the remnants of 

 what had occurred were still not persisting up- 

 stream of the Grand Banks. 



WATER MASS ANALYSIS 



The water mass analysis. Figure 25, pre- 

 sents temperature-salinity information based 

 on a 19-year running average and data col- 

 lected by the 1966 International Ice Patrol. 

 Station data from stations 9509 to 9551 were 

 used to carry the averages forward. Because a 

 careful search of previous bulletins failed to 

 reveal the procedure used to determine what 

 constitutes Mixed Water, Atlantic Current 

 Water, and Labrador Current Water, these 

 temperature-salinity curves will be discussed 

 in a separate section at the end of this report. 

 Historical International Ice Patrol usage had 

 named the northeastward extension of the Gulf 

 Stream past the "Tail-of-the-Banks" the At- 

 lantic Current. This usage is maintained in 

 describing the water mass analysis, but the 

 more accepted term. North Atlantic Current, 

 is used in the remainder of this report. 



This year there was not a sharp delineation 

 between Labrador Current Water and Mixed 

 Water on Standard Section 3 and 4. There was 

 even a more hazy line between Mixed Water 

 and Atlantic Current Water. This resulted in 

 a considerable number of stations having 

 water characterized as atypical in the upper 

 300 meters. In the classification scheme used 

 these atypical points were not presented. Fig- 

 ure 25 shows that the water characterized this 

 year as Labrador Current Water was more 

 dense from 50 to 300 meters than the 19-year 

 average Labrador Current Water. It was sig- 

 nificantly warmer level for level to 1000 

 meters and more saline than the 19-year 

 average values in the top 400 meters. The 

 Mixed Water observed this year was more 

 dense and more saline than the 19-year aver- 

 ages in the top 300 meters. It was also warmer 

 in the 50 to 150 meter interval. The Atlantic 

 Current Water observed by the International 

 Ice Patrol was significantly fresher and cooler, 

 level for level, than the North Atlantic Cur- 

 rent Water characterized by the 19-year aver- 

 age. Similarly the density of this water was 

 greater level for level than the 19-year average 

 values. No attempt will be made to explain why 



14 



