Surface maxima north of Cape Cod 

 (Nantucket data misBing) vrere greater by 

 2'F and k°F at Portland Lightship and 

 Georges Shoals respectively than In 1956; 

 at Boston Lightship it was lower by 0.7'F. 

 From Ambrose through Savannah Lightships 

 (Diamond Shoals excepted) surface maxima 

 were both earlier and lower than in 1956. 

 Thus, north of Cape Cod summer surface 

 temperatures followed a smooth curve, 

 roughly psurallel to the mean, whereas 

 south of the Cape temperatures leveled off 

 abruptly £ifter the first 10 days of July. 



Bottom temperature . 



At the bottom along the continental 

 shelf both minimum and maximum temperatures 

 occur during isothermal conditions of late 

 winter and early fall. Thus, the 1957 

 bottom minima, like the surface minima, 

 were above those for 1956. This was true 

 of all stations with the exception of 

 Nantucket, where an Intrusion of cold water 

 at depth occurred in what hsid been a 

 completely mixed colxmm two weeks earlier. 



Maximum temperatures at the bottom 

 occurred at the same time or earlier than 

 in 1956. As should be expected they occur 

 at the time of the autumn overturn which 

 mixes bottom water with the wanner water 

 of the upper layers. Thus, bottom maximum 

 temperatures are dependent upon the time 

 of occurrence of aufomn storms. Early 

 autumn storms which abruptly destroy the 

 thennocline produce high bottom maxima as 

 in 1957; if the overturn is delayed until 

 cooling is advanced at the surface, bottom 

 maxima will be relatively lower as in 1956. 

 This explains how the bottom maxima could 

 be generally higher in 1957 than in 1956 

 (as they were from Boston to Winter Quarter, 

 inclusive), even though the surface maxima 

 were generally lower. It also points out 

 the dangers inherent in trying to postulate 

 bottom conditions from a knowledge of sur- 

 face temperature regimes. 



