As a first approximation it Avas assumed that the mean temperature 

 of the East Greenland Current was constant at 3.2° C, the vakie of 

 the mean temperature of the water contributed to the West Green- 

 land Current from the eastward in 1949 when the Irminger Current 

 was almost completely absent ; and that the mean temperature of the 

 Irminger Current was constant at 5.5° C, the highest recorded value 

 of the mean temperature of the West Greenland Current (September 

 1928). From the total volume of flow of the West Greenland Current 

 and the total heat transport of that current the volume of flow of 

 each of the components was then computed for the 13 occupations 

 of the section which are available over the years from 1928 through 

 1949. The 13 values for each component were then plotted against 

 time of year with the results sho^n in figure 32. 



There appears to be a seasonal summertime increase in the volume 

 of flow of the Irminger Current and a seasonal summertime decrease 

 in the volume of flow of the East Greenland Current as they con- 

 tribute to the West Greenland Current at Cape Farewell. The two 

 curves representing these fluctuations and the curve, derived from 

 their sum, representing the seasonal fluctuation in the West Green- 

 land Current are approximations both because the mean tempera- 

 tures of the two parent currents probably are not constant, as as- 

 sumed ; and because of the small number of points on which they are 

 based. A southward shift of the northern boundary of the North 

 Atlantic eddy, whether arising from a shift of the entire eddy or 

 from a contraction of the eddy, would have the effect of reducing the 

 Irminger Current. Such a reduction conceivably could take jilace 

 with little or no noticeable change in the northward transport of 

 salt or water-borne heat in the area east of Iceland. In such a cir- 

 cumstance as occurred in the summer of 1949, however, Avhen prac- 

 tically no Irminger Current water reached Cape Farewell, a much 

 greater reduction in the supply of water-borne heat to the Arctic 

 could result. 



A seasonal latitudinal shift of the northern boundary of Atlantic 

 Current water in the Grand Banks sector of the North Atlantic eddy 

 has been found and reported in Bulletin No. 31 of this series,^ and 

 has been correlated with the volume of flow of the Labrador Current 

 and with the seasonal fluctuation in the different in sea level across 

 the Gulf Stream at the Charleston-Bermuda section 131/2 months 

 earlier. If a time lag is involved between the Grand Banks sector 

 and the Irminger Current, it might be expected to be of the same 

 order of magnitude. Thus, if the surveys made in the Grand Banks 

 region during a particular ice season show the boundary of Atlantic 



3 Soule, Floyd M., and C. A. Barnes, "International Ice Observation and Ice Patrol Service 

 in the North Atlantic Ocean — Season of 1941." U. S. Coast Guard Bull. No. 31, pp. 15-24 

 (1950), Washington. 



85 



