for several hours preceding the current observations. As might well 

 he anticipated, similar plots of data from Station A where winds were 

 highly variable showed no clearly defined wind-driven characteristics. 



A marked thermal stratification existing during the svirvey may 

 partly account for the departures of the observed vertical current pro- 

 files from theoretical current distributions derived for vertically 

 homogeneous water. Defant (1961) and Nomitsu (1933) describe the in- 

 fluence of such stratification on a surface drift current. Their stud- 

 ies indicate that a larger deflection from the wind direction is expe- 

 rienced when an homogeneous surface layer of small thickness is devel- 

 oped, such as that existing during the period of the described observa- 

 tions. This effect, as well as the distortion produced by the net 

 southeasterly transport over the Bank, may account for the greater de- 

 flection to the right of observed currents than would be expected for 

 vertically homogeneous water. It is also postulated that the rather 

 sharp cutoff of wind-driven characteristics of the vertical velocity 

 profile at the approximate depth of the thermocline may be a further 

 manifestation of the essentially two-layered system produced by the 

 sharp density transition. 



Despite certain pitfalls involved in the interpretation of pro- 

 gressive vector diagrams, it is felt that they materially improve 

 illustration of the current phenomena treated here. An immediate ap- 

 plication of such, diagrams is the graphical approximation of the net 

 water movement over the fenk based on observed currents. Further ap- 

 plications include the ready visualization of time changes and rotary 

 characteristics. 



Net hourly displacement, net daily displacement, and average ob- 

 served currents have been computed for each observational depth at 

 Stations A, B, and C. These values, presented in Appendix F, siunma- 

 rize the average features of water movement over the Bank based on one- 

 day intervals of data from each station. Net dally displacements were 

 graphically determined from the progressive vector diagrams by measur- 

 ing the magnitude and direction of the resultant 2ij^-hour vector. The 

 net hourly displacements can be compared with observed velocities. It 

 is noted that the mean observed hourly velocity closely approximates 

 the net hourly displacement except at Station A, where the current dis- 

 played rotary characteristics and was considerably smaller in magnitude 

 than it was at Stations B and C. Average current speeds at Stations B 

 and C were nearly identical; however, net current directions at Station 

 B were southerly, while those at Station C were approximately south- 

 southeasterly. Average net directions at Stations A, B, and C are 141°, 

 183°, and 15^° T, respectively. 



The marked continuity of the current observations obtained during 

 this study is revealed by comparisons of the progressive vector dia- 

 grams from depth to depth as well as from station to station. The char- 

 acteristic shape of the displacement tracks at a partictilar station is 

 replicated with certain minor distortions at each observational depth. 



