+ 3 



+ 2 



o 



+ 3 



+ 2 



3 



-3 



Figure 8. — Observed and adjusted mean bottom-water temperature 

 anomalies in the southern Middle Atlantic Bight during spring 

 1968-76 and autumn 1967-76. The "O" base lines are based on the 

 seasonal time-series mean temperatures during each season. 



Table 9. — Bottom-water temperature anomalies in the south- 

 ern Middle Atlantic Bight during spring 1968-76 and autumn 

 1967-76. 





Spring anomalies (°C) 



Autumn anomalies (°C) 



Year 



Observed Adjusted 



Observed 



Adjusted 



1967 



No data 





-0.9 



-1.2 



1968 



-1.5 



-0.8 



-0.8 



-0.9 



1969 



-1.8 



-1.1 



+1.7 



+ 1.5 



1970 



-0.3 



-2.9 



-3.5 



-1.7 



1971 



-0.8 



-1.4 



-0.7 



-1.1 



1972 



+0.8 



+ 1.4 



+2.5 



+ 1.9 



1973 



+0.1 



+0.1 



+0.5 



-0.2 



1974 



+ 1.2 



+2.6 



+0.5 



-0.2 



1975 



+0.4 



+1.0 



+0.5 



+ 1.2 



1976 



+ 1.1 



+ 1.5 



+0.6 



+0.2 



i indices 



7.7 



7.5 



13.4 



13.8 



for observed and 3.2°C for adjusted) was in 1970, the 

 coldest autumn, while the largest increases (3.3°C for 

 observed and 3.1 °C for adjusted) was in 1972, the warm- 

 est autumn. The 10-yr adjusted mean index was 13.8°C 

 and the observed mean was 13.4°C. 



Figure 8 and Table 9 also show the autumn anomalies 

 which, except for 1969, were negative in the first 5 yr of 

 the series and positive or only slightly negative during 



16 





1 1 1 



i 1 



i I i i i 



M 

 li A 



15 

 o 







— 







/' A 



// A ' v 

 /' \ ' x 



% 14 



- 







jj \\ \ 



ir. 



i \ . ' _ 



MEAN BOTTOM-WATER Tl 





1 " J J 





// \ 

 I 1 



A \ 



7 



1 /; 



» /' 

 \ ji 



\ V 



i / / 



>// 



i v i 



10-YR X's 

 AUTUMN 









OBSERVED 



11 









ADJUSTED 



10 



- 



l 





I [ I 



1967 



69 



73 



75 



YEAR 



Figure 9. — Observed and adjusted annual and long-term mean 

 bottom-water temperatures in the southern Middle Atlantic Bight 

 during autumn 1967-76. 



the last 5 yr. The anomalies are quite similar to the 

 spring series and generally reflect a warming trend over 

 this latter time period. 



On the average, the 10°-12°C TCI was the largest 

 (24%) while the remaining TCI's between 8° and 20°C 

 averaged 11-17% to account for over 90% of the thermal 

 bottom layer (Table 4). Although the warm years 1973-76 

 had the same or very nearly equal observed tempera- 

 tures, only the 10°-12°C TCI was similar in all 4 yr. Dur- 

 ing three nearly equally cold years — 1967, 1968, and 

 1971 — the colder and warmer TCI's also varied consider- 

 ably. One of the colder years (12.7°C in 1971) actually 

 had more or equal amounts of water >16°C than two of 

 the warmer years (13.9°C in 1973-74) but was regulated 

 by a large amount (27%) of water <10°C. 



DISCUSSION 



Causes of Temperature Variations 



Specific identification of water masses is speculative in 

 this paper because supportive salinity data were either 

 nonexistent or unavailable at the time of this analysis. 

 However, other investigations on the relationship of the 

 shelf-slope interface allow some general conclusions to be 

 made based on temperature data alone, at least for the 

 spring observations. Based on the position of the 10°C 

 isotherm (Figs. 2, 3), it can be seen that in the spring 

 there was a greater encroachment of slope water onto the 



10 



