NO A A PROFESSIONAL PAPER 11 



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FIGURE 3-10 — Time profile of monthly average wind speed in m/s (solid line) and scalar wind variance 

 in (m/s)- (dashed line) at John F. Kennedy International Airport, computed from 3-hourly obser- 

 vations, 1949-76 — continued. 



WIND STRESS AND VERTICAL MOTION 



Using the method described earher, the average monthly 

 wind stress over the Bight for February-June is presented 

 in figure 3-11. The average monthly surface wind stress 

 vector had a component towards the north for all months 

 February through June, consistent with the resultant wind 

 flow analyses of figure 3-7. Whether a mean northward 

 component of flow at the surface and offshore surface 

 Ekman transport were set up in the Bight 2 to 3 months 

 earlier than usual is not known. However, the results sug- 

 gest the possibility of some anomalous circulation features 

 during these months. 



There are two mechanisms for wind-driven upwelling. 

 One operates in the open ocean, independent of coastal 

 boundaries. It involves the open ocean divergence of the 

 surface Ekman transport, which depends upon the curl of 

 the wind stress and the change in the Coriolis parameter 

 with latitude, and it applies to mid-shelf and outer-shelf 

 regions. The other operates in coastal regions, and de- 

 pends upon the existence of coastal boundaries. It involves 

 the coastal divergence of the surface Ekman transport, 

 which depends upon the orientation of coastal boundaries 

 relative to the wind stress vector, and it applies to inner- 

 shelf regions. The effects of both mechanisms have been 

 evaluated for the bight and are discussed below. 



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