the Bermuda-Charleston section and the Grand Banks region. Leading 

 phase differences were neglected as having no physical significance. 

 Because each year's oceanographic measurements covered a period of 

 about 3 months (April, May, and June), the sea level data for the 

 corresponding 3-month period centered at 13^ months, 5}4 months, 

 71-2 months, and 10^2 months earlier were averaged for comparison 

 by years. This >ear b\- year comparison showed that a good negative 

 correlation existed between the difference in sea level, Bermuda minus 

 Charleston, and the adjusted area 13J^ months later, a fair positive 

 correlation agreed with the 5^/2 months lag, and no correlation was 

 apparent in regard to the other intervals. Thus the June maximum in 

 adjusted area in the Grand Banks region seemed to be closely asso- 

 ciated with the spring minimum in volume of flow of the Gulf Stream 

 the preceding year and possibly- to be associated with the maximum in 

 volume of flow of the Gulf Stream the preceding winter. 



The two lags of 53^ months and 1334 months were then tested 

 surve\' b\- survey, the former giving no definite relationship and the 

 latter giving the results shown in figure 15. In this figure the broken lines 

 connect points representing the adjusted area determined from in- 

 dividual surveys. The solid lines represent the difference in sea level 

 between Bermuda and Charleston 1334 months earlier, the smooth 

 curves being based on the horizontal lines which represent the monthly 

 means. While the shape of the curves representing the difference in sea 

 level is fairh- well determined b\' the stipulation that for any month the 

 algebraic sum of the areas between the curve and the monthly mean 

 must equal zero, the shape of the curves representing the adjusted 

 area is not so definitely determined between points representing ob- 

 served values. It will be seen that the curves connecting the observed 

 values can be drawn, in the manner shown, to give a good agreement 

 with the difference in sea level 1332 months earlier, except that the 

 time difference preceding the 1939 season seems to have been about 

 14 months instead of 133^. The fluctuation in adjusted area for 1942 has 

 been predicted on the basis of sea-level fluctuations in 1941 and the 

 correspondence between the two curves for the preceding 8 years. 



From this comparison of fluctuations in the difference in sea level 

 between Bermuda and Charleston and the adjusted area in the Grand 

 Banks region it would appear that an increase in difference of sea level 

 is followed b\- a southward movement of the outer boundar\- of the 

 Atlantic Current in the Grand Banks region 534 months later and by a 

 northward movement of the boundary 1334 months after the change 

 in sea level; with the southward movement traceable only if the sea 

 level change was consistent for a period of about 3 months, but with 

 the northward movement responding to much shorter changes in sea 

 level, of as little as five days. Consideration of the signs of these correla- 

 tions, the magnitude of the time lags, and the definition of the boundary 

 leads to the possibility that our boundary criterion, being based on a 



19 



