UPPER CURRENT METER 



gS SECONDS 



e.o r 



1.8 - 



1.0 - 



0.0 



.s vv^A^MHAuAAA^V^'^^W^ 



MIDDLE CURRENT METER 



gS SECOND S 

 S.0 r 



3 .6 

 0.0 



1.6 



1.0 



.6 



0.0 



V^AVWK^..x^w^->^W\J'^^ 



BOTTOM CURRENT METER 



gS SECOND S 

 2.0 r 



•NA^A^~-A/v.v/Ay-^ 



Figure 4. Longshore component current time histories at three elevations in 

 the surf zone of eastern Lake Michigan (from Meadows, 1976). 



The ongoing NSTS project assumes a uniform vertical velocity structure 

 in the surf zone, in that no vertical current meter arrays are employed. 

 However, the rip currents are being observed by a portable device that per- 

 mits vertical velocity profiles to be taken (Gable, 1979). No results of 

 vertical distributions are available at this writing. 



29 



