interstation intervals as compared to the usually accepted values 

 of unity or greater. 



The average value of AD GEK — AD 1,000 deb was computed to 

 be + 8.6 dynamic mm with a probable departure from average of 

 dz 103.2 mm. The average interstation interval was 28I/2 miles. 

 When the equivalent difference in dynamic height was uncorrected 

 for drift the average became + 7.7 ± 107.6 dynamic mm. From 

 this it is concluded that the correction for drift is unimportant and 

 need not be considered until the larger sources of discrepancy have 

 been remedied. 



By applying the cumulative values of AD GEK to the dynamic 

 height at station 4175, quasi-dynamic heights were computed for 

 the remainder of the stations and a chart of dynamic topography 

 was drawn using these values. Comparison of this chart with one 

 drawn exclusively from density considerations showed agreement 

 only in the coarsest features of the circulation pattern and this 

 method of constructing a current chart was not considered satis- 

 factory. 



In order to distribute the discrepancies between AD GEK and 

 AD 1,000 deb and thus preserve more of the circulation pattern 

 found by considering only the density distribution, the computed 

 quasi-dynamic heights were set equal to the dynamic heights at 

 four points, stations 4175, 4185, 4195 and 4205, and the differences 

 proportioned between these stations by adjusting AD GEK. This 

 method produced a current chart which was closer to the chart 

 constructed from density computations, but which still left much 

 to be desired. 



If a major source of the discrepancies was the measurement by 

 dynamic topography of the steady state, as compared with the meas- 

 urement by the current meter of the sum of the steady state and 

 the fluctuating currents ; and if, because of the weak winds which 

 characterized this particular survey, the aperiodic currents were a 

 negligible part of the fluctuating currents ; then the discrepancies 

 might be expected to represent in large measure the periodic fluctua- 

 tions. An analysis was therefore undertaken as follows. The 

 GEK current vectors, usually determined each half hour, were 

 superimposed on the dynamic topographic chart and at each of 

 these points the geostrophic current vector was scaled from the 

 chart. The vector differences were then resolved into their north- 

 south and east-west components and plotted against time beginning 

 at station 4175. For the first 2 days there seemed to be a poorly 

 defined period of about 18 hours in the north-south component. 

 No other periods were apparent from inspection of the curves. If 

 the errors of measurement contributed a negligibly small part to 

 the discrepancies between the GEK measurements and the dynamic 



35 



