Paper 19 



During 1976^ as in 1974/ no data were obtained to indicate that 

 bottom temperatures in the warm Slope U;ater zone fell below 1 2 C /• 

 as they did on at least t«jo occasions in 1975. The apparent 

 absence of a minimum temperature interval in March is particu- 

 larly interesting/' because such an event occurreo in 1975 and was 

 stronnly evident in long-terTi Tionthly mean bo'ttom temperatures 

 for the years 194u-66 (Chamberlin 1973). The apparent absence of 

 such a minimum in March 197A can be explained by the persistence 

 of a warm core Gulf stream eddy south of New England during that 

 month (Chamberlin 1975). In 1976/ however/ no warm eddy was 

 detected in that region during the entire winter and early 

 sprino. It seems possible/ although questionable/ that bottom 

 temperatures at such a depth as the warm Slope Water zone 

 remained above 12C during March 1976 because of the record warm 

 air temperature during the preceding month (Dickson 1976). 



Two strong incursions of Slope Water onto the upper slope and 

 outer shelf are evident: the first in early February and the 

 other in October; but only the latter appears to have caused 

 shoreward displacement of the slope front (see discussion of 

 sect i ons 2 and 13). 



Bottom temperature variations can be associated with each of the 

 three Gulf Stream warm core eddies that passed south of New 

 England during 1976 (Fig. 19.2). During 'Aay f eddy 76B presumably 

 caused the observed elevation of bottom temperatures to above 13C 

 in the warm Slope Water zone. During mid-August/ the presence of 

 eddy 76C was probably reflected in the deepening of isotherms (as 

 much as 80 m) at depths below 15C m. Another effect of this eddy 

 may have been a temporary rise in bottom temperature to above 13C 

 in the warm zone/ as suggested by dashed lines in Figure 19.2. 

 The occurrence of such a bottOTi temperature rise is indicated in 

 sections 9 and 10/ although not actually shown in either of these 

 sections. In November/ eddy 76D probably caused the observed 

 rise in bottom temperatures to above 14C (probably above 15C) in 

 the warm zone. The deepening of isotherms at depths below 160 m 

 may also have been caused by this eddy. 



SUMMARY 



Shelf Water temperatures during the spring/ particularly as 

 observed at the bottom/ were about 1C warmer than in 1974 and 

 about 2C warmer than in 1975/ probably as a result of record warm 

 air temperatures in February and moderate air temperatures in the 

 following few months. 



Marked cooling and deepening of the surface layer was recorded on 

 the shelf following the passage of hurricane Belle in early 

 August . 



324 



