Using the procedure described above, current charts have been 

 constructed from the GEK vectors observed during the surveys 

 made 9-20 June 1950, 3-15 April 1951, 29 April-10 May 1951, and 

 23 May-4 June 1951. The resulting charts are shown in figures 

 13 to 16 and are to be compared with the dynamic topographic 

 charts shown in figure 18, Bulletin No. 36 of this series, and 

 figures 7, 8, and 9 of this bulletin. In preparing figures 13 to 16, 

 no correction has been applied to the magnitudes of the GEK 

 vectors for the departure of the proportionality factor from unity 

 or of the vertical intensity of the earth's magnetic field from 

 50,000 y. The current speeds indicated by the GEK charts, there- 

 fore, are not exact but the directions and current patterns should 

 be comparable to those shown in the charts of dynamic topography. 



In figure 13 the diiference in current pattern from that shown 

 by the dynamic topography are greatest in the vicinity of 43° N., 

 49° W., and near 45° N., 47° W. Near the eastern edge of the 

 Grand Banks at about 45° N., figure 13 shows a number of contour 

 lines which are not present farther north. While the sources of 

 such a discrepancy include the possibility of cumulative error of 

 the GEK vectors and convergent flow, probably a major source is 

 the treatment as synoptic a series of observations of fluctuating 

 currents made over a considerable period of time. The relative 

 speed of the current near the southern extreme of the survey is 

 lower than expected and may be an instance of the smoothing out 

 of peak velocities arising from the averaging process described 



above. 



Figure 14 shows a difference in current pattern from that of 

 figure 7 in the area near 43° N., 49° W., and marked differences 

 in relative speed shown by these figures are present in the extreme 

 western and northeastern parts of the surveyed area. 



In comparing figure 15 with figure 8, we find general agreement 

 in the eastern branch of the Labrador Current and disagreement 

 in the vicinity of Flemish Cap and Cape Bonavista. In each of 

 these cases the disagreement is considered to be the result of 

 periodic fluctuating currents. It is to be noted that the disagree- 

 ment between the GEK and dynamic topography seems to be no 

 worse for this survey than for the southern part of the survey 

 made in June 1950, although the latter was made during excep- 

 tionafly quiet weather and the former during exceptionally boister- 

 ous weather. 



The comparison of figure 16 with figure 9 shows areas of dis- 

 agreement near 43° N., 48° W., and 46° N., 46° W. While it is 

 noted that the areas of disagreement consistently occur along the 

 outer margins of the North Atlantic Current in the four charts 

 presented here, the degree of consistency is insufficient to warrant 

 conclusions as to the principal cause of the disagreements. 



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