USCGC EVERGREEN stations 21-A through 

 21-D and USCGC NORTHWIND station 17 

 (fig. 6). Considerable Norwegian Sea Water 

 was present at stations 21-B and 21-C but none 

 was apparent at stations 21-A, 21-D, and 

 USCGC NORTHWIND station 17. This was il- 

 lustrated further by determination of propor- 

 tion of Norwegian Sea Water present (figs. 15- 

 19). Also noteworthy was the relatively greater 

 amount of Norwegian Sea Water at shallow 

 depths in the vicinity of USCGC EVERGREEN 

 station 20 during all but the initial occupation 

 of the station (figs. 18-20). In general the 

 amount of Norwegian Sea Water in the section 

 increased throughout the survey. 



DISTRIBUTION OF PROPERTIES 



The temperature of the upper few hundred 

 meters became cooler during the USCGC 

 EVERGREEN survey (figs. 22-25). The loca- 

 tion of the 9°C isotherm was approximately 

 constant throughout the surveys; sloping from 

 about 200 meters depth near Iceland to 800 me- 

 ters depth near Scotland. Above this isotherm 

 the temperature gradient diminished in time 

 owing to cooling of the surface layers and more 

 nearly approached isothermal conditions in the 

 last section. The USCGC NORTHWIND section 

 (fig. 21) showed a considerably warmer surface 

 temperature and a much shallower 9°C iso- 

 therm indicating development of a seasonal 

 thermocline. The permanent thermocline ex- 

 tends from the 8°C isotherm to the 5°C iso- 

 therm (figs. 21-25), and is also characterized 

 by an oxygen minimum (figs. 36-40). 



The overall temperature distribution between 

 Iceland and Outer Bailey Bank did not vary 

 significantly from survey to survey. There were 

 significant changes in the near-bottom temper- 

 atures between Iceland and Outer Bailey Bank, 

 however, as pointed out by variations in comput- 

 ed quantities (CB/CA) of Norwegian Sea 

 Water present. There is good correlation be- 

 tween the 0.5 CB/CA isopleth and the 3.0°C 

 isotherm. 



The temperature distribution below 400 me- 

 ters between Outer Bailey Bank and Scotland 

 did not change greatly during the USCGC 

 EVERGREEN survey. The average depths of 

 the isotherms remained approximately constant 

 with only a slight cooling (<0.5'C) near the 



middle of the section. Bottom water tempera- 

 tures in this area did not vary appreciably on 

 any of the surveys. 



The salinity distribution in the section be- 

 tween Iceland and Scotland did not change sig- 

 nificantly during the surveys (figs. 26-50). In 

 addition, the horizontal and vertical gradients 

 were small; with almost the entire body of 

 water having salinity values between 35.00%o 

 and 35.40%o. 



As a consequence of the relatively static sa- 

 linity distribution, changes in density reflect 

 changes in the temperature distribution ; there- 

 fore, the most noticeable density changes were 

 in the upper 300 to 500 meters of water. Be- 

 neath 500 meters the density distribution was 

 quite constant except for the bottom layers be- 

 tween Iceland and Outer Bailey Bank, where 

 density changes were re'ated to variation in the 

 quantities of Norwegian Sea Water present. 



CONCLUSIONS 



Variation of temperature above the perman- 

 ent thermocline due to seasonal cooling was 

 quite pronounced but the changes that occurred 

 beneath it were somewhat less obvious and re- 

 lated to advection of Norwegian Sea Water. The 

 maximum proportion of Norwegian Sea Water 

 observed on each section varied frcm 0.301 to 

 0.684 (figs. 16-20). The distribution of the 

 Norwegian Sea Water present also varied and 

 extensive distribution was not necessarily 

 asssociated with high proportions. For ex- 

 ample, the individual calculations of the 

 proportion of Norwegian Sea Water during the 

 USCGC NORTHWIND section were relatively 

 low (<0.301) yet Norwegian Sea Water was 

 more widely distributed on this section than on 

 some of the USCGC EVERGREEN sections 

 which had higher individual calculations. 

 Whether this is indicative of changes in the 

 quantity of Norwegian Sea Water passing 

 through the section or merely indicates a differ- 

 ent mixture of an approximated constant a- 

 mount of Norwegian Sea Water cannot be de- 

 termined with the available data. Future study 

 of the variability of the interchange should in- 

 clude continuous temperature and salinity mea- 

 surement to within a few meters of the bottom. 

 Other methods, such as the measurement of 

 preformed nutrients, should also be applied to 

 more carefully define the water types present. 



3 



