Ambrose Lightship (Figure 10, Table 10) 



Surface temperatures indicate near "normal" conditions for 

 Janxiary and February, and early warming beginning in mid-Karch, vdth tem- 

 peratures above the mean and above the 19^6 readings. There was a sharp 

 decline during the first 10 days of Jiily, which was accompanied by an 

 intrusion of relatively cold water at the bottom. Similar conditions 

 were seen in 1956 from Five Fathom Bank as far south as Frying Pan Shoals. 

 The intinision was more pronounced and more extensive in 1957j but as Bum- 

 pus has indicated the phenomenon may well be a normal occurrence, pro- 

 duced to a greater or less extent each summer by a seasonal change in the 

 wind system conducive to upwelling of sorts. (See Chesapeake Lightship 

 below) After this intrusion temperatures recovered only to fall off 

 agciin during Aiigust. The siUTuner maximum vjas earlier and cooler than the 

 mean and the 1956 record. 



The winter minimum of less than 59*'F extended to a depth of 50 

 feet; this was ca. 1 degree warmer than the 1956 minimum. The thermo- 

 cline started to develop in mid-April with temperatures in the mid-UO's 

 and was broken down by the end of October. 



It is probable that both maximum and minimum salinities were 

 missed. The pattern, however, is quite similar to that seen in 1956 ex- 

 cept that after the spring ininoff there is less difference between sur- 

 face and bottom values than appeared a year earlier. 



53 



