The 4.0° C isotherm was relatively compli- 

 cated and some subjective contouring was re- 

 quired because of the location of station 28 

 and because temperature was not an another- 

 mic function of depth. The 4.0° C isotherm 

 may have intersected the continental slope as 

 did the 34.0%o isohaline. The position of the 

 4.0° C isotherm and the 34.0%o isohaline this 

 far west was not anomalous. Kollmeyer et al. 

 (1965) presented temperature and salinity 

 vertical sections for Standard Section 3 (Sec- 

 tion U) for the three surveys conducted during 

 the 1965 Ice Patrol Season. The results of the 

 first survey from 30 March to 7 April 1965 

 showed a similar distribution of these two 

 isopleths. 



The nature of the Labrador Current in the 

 winter is not known because of the paucity of 

 data. Smith (1937) using iceberg drift data 

 questioned whether or not the Labrador Cur- 

 rent existed during the winter. Presently there 

 is no winter oceanographic data available, but 

 the lack of southward flowing cold, relatively 

 fresh, water is considered anomalous. The min- 

 imum temperature and salinity found along 

 this section were at the surface of station 27. 

 These values are 1.16° C and 34.49%o. A cold 

 core (i.e., temperature less than 0.0° C) was 

 expected, but it was not observed. The south- 

 ward flowing water between stations 27 and 

 30 was not excessively warm when compared 

 to 0.0° C. 



Between stations 28 and 30, a warm (5.0° C) 

 saline (maximum salinity 34.92%,,) core of water 

 was moving slowly southward. A temperature- 

 salinity diagram (Figure 25) characterizes this 

 as Mixed Water. 



At the eastern end of the section there was 

 an indication of a cool, saline North Atlantic 

 Current, but the mean temperature-salinity re- 

 lationships for the Grand Banks region did not 

 support this. They indicated that the surface 

 200 meters at station 36 consisted of atypical 

 mixed water. This indicated that the mixing 

 zone extended from station 29 eastward past 

 station 36. Water at intermediate depths at 

 these stations has North Atlantic Current 

 characteristics, but the deepest observed data 

 at station 36 have mixed water characteristics. 



In summary, the factors considered anoma- 

 lous are : 



1. The lack of sub-zero water in the core 

 of the Labrador Current. This may be a nor- 

 mal condition; however, USS MUSKEGONON 

 bathythermograph data from 8-9 February 

 1946 at 46°10'N across the Labrador Current 

 showed a large amount of water with tempera- 

 tures less than 0.0° C.i 



2. The failure of Standard Section 3 to indi- 

 cate the North Atlantic Current. All previous 

 data indicated that this section should have 

 completely crossed the Mixed Water and ex- 

 tended into the North Atlantic Current. 



CGC HUMBOLDT 9-11 MARCH 1966 

 OCCUPATION OF STANDARD SECTION 3 



The CGC HUMBOLDT occupied Standard 

 Sections 2 and 3 during 9-12 March 1966. 

 These occupations preceded the scheduled oc- 

 cupation by the International Ice Patrol by 3 

 weeks and was earlier in the year than any 

 previous International Ice Patrol occupation. 

 The vertical distribution of temperature and 

 salinity is presented in Figures 10 through 13. 

 The dynamic height topography along each 

 section is shown in Figures 14 and 15. A chart 

 of the dynamic topography is shown in Figure 

 16. Standard Section 2 occupations will be 

 considered after the Standard Section 3 dis- 

 cussions are completed. 



Several interesting features can be noted in 

 Figure 14. There was a relatively swift (33 

 cm/sec) current flowing southward between 

 stations 28 and 29. However, the maximum 

 velocity observed was slightly less than half of 

 that observed during the 14-15 February oc- 

 cupation. Both the maximum (970.012 dy- 

 namic meters) and the minimum (970.868 

 dynamic meters) values of dynamic height 

 have decreased from those observed previously. 

 The dynamic height on the shelf became 

 smaller and the trough deepened and moved 

 toward the east. The distance between compar- 

 able shelf and trough stations was 44 nautical 

 miles, i.e., the distance between the maximum 

 and minimum dynamic height values was 44 

 nautical miles. 



In addition to the trough deepening, a 34.5 

 cm/sec northward flowing current was ob- 

 served between stations 31 and 32. Again the 



' Unpublished bathythermograph data available at 

 the Coast Guard Oceanographic Unit. 



