64 



ATKINSON 



Fig. 6 Photographs a and b show right-handed vertical current profile. Photograph c shows the left-handed vertical current pro- 

 file 2 km north of Enewetak Island. Direction of current and depth of dye dispenser are shown in the line drawing below the pho- 

 tographs. See Fig. 7 for location. [From Atkinson et al. with permission.] 



Surf 



The breaking waves on the windward reef drive water 

 over the windward reef flat and into the lagoon primarily 

 on the eastern (prevailing windward) side of the atoll. The 

 cross-reef currents and the currents behind the reef are, 



therefore, dependent on the surf height and the depth of 

 water on the reef. This oceanic water spreads into the 

 lagoon, moving downwind and mixing vertically and hor- 

 izontally. Since the South Channel is the only significant 

 region of outflow, the water column has a net transport to 

 the south. This southerly net volume transport must 



