Boston Lightship (Figvire k. Table k) 



The 1957 sxirface water temperatures in terms of 10 day means 

 were generally higher than the mean for the 192^-19Ui. period and were 

 for the most part above the 1956 readings. 1957 was characterised by 

 early warming, an early maximum in late July and, except for a brief 

 period in the fall, by slower than normal cooling. The thermocline be- 

 gan to develop in late March and was destroyed by early November; in 

 structure it was very similar to that of the previous year. The annual 

 mean surface temperature was 50.0 degrees or l.ii degrees higher than in 

 1956. 



Salinities held higher and more unifonn than in 1956. The 

 minimum at the surface was about 31.7 "/oo in May with the maxima in 

 Janiiary, February, March and December of 32-5 °/oo; this gives a range 

 of less than 1.0 °/oo contrasted with a range of 2.0 °/oo the previous 

 year. As in 1956 bottom salinities were .50 to .75 °/oo higher than the 

 surface during the period of the thermocline. 



21 



