remarkable similarity. The summer minimum in the positive curve may he 

 caused hy excessive heating of the mixed layer. This heating effect does 

 not extend through the thermocline. The autumn maximum may resiilt from 

 temperature increase at too feet caused by intense mixing by autumn storms. 

 The secondary minimum and maximum of the positive curve in spring and the 

 ratio distribution of negative anomalies are not as easily explained. 



VI. CORRELATED AND UNCORRELATED ANOMALIES 



About 16 percent of the pairs of anomalies are reversed; i.e., if 

 positive at the surface, they are negative at 400 feet and vice versa. 

 It appears logical to assume that cases of reversed anomalies must be of 

 different origins and are not correlated. There are 37 such pairs of 

 anomalies in a total of 237 pairs greater than 0.5°F in the combined data 

 of the Atlantic stations. Monthly distribution of the 37 uncorrelated 

 observations with differing signs is shown in figure 9. Total distribution 

 (figure 9a) shows that about 73 percent of all uncorrelated observations 

 with differing signs occurred in the summer months from June through 

 September, and 93 percent of these were positive at the surface and neg- 

 ative at 400 feet (figure 9b). The distribution of anomalies negative 

 at the surface and positive at 400 feet is shown in figure 9c. 



J F M A M 



a. Combined observations 



J FMAMJ JASON 



b. Anomalies positive at surface, negative at 400 feet 



















































^» 



^^ 



SSS^ 



^SM 



MMSJ 



MSM 



JFMAMJ JASOND 



c. Anomalies negative at surface, positive at 400 feet 



FIGURE 9 DISTRIBUTION OF UNCORRELATED PAIRS OF ANOMALIES OF DIFFERENT 

 SIGNS AT SURFACE AND 400 FEET AT NORTH ATLANTIC OCEAN 

 WEATHER STATIONS 



23 



