known time lags and elevation anomalies. The data were plotted, and a new 

 listing was generated and rechecked. When the validity of the data had been 

 confirmed, monthly tabulations of daily highs and lows, hourly heights (in- 

 stantaneous height selected on the hour), and various extreme and/or mean 

 water level statistics were computed. The monthly or annual mean sea level 

 (msl) reported is the average of the hourly heights, while the mean tide level 

 (MTL) is midway between mean high water (MHW) and mean low water (MLW). 



Visual Observations 



48. Daily visual observations were made near 0700 hours to supplement 

 instrumented data collection. These include observations of surface current 

 speed and direction at (a) the seaward end of the pier, (b) the midsurf posi- 

 tion on the pier, and (c) the beach 500 m updrift of the pier. Surface cur- 

 rents were determined by observing the movement of dye on the water surface. 

 Surface current speed and direction at the FRF are influenced by winds, waves, 

 tides, and indirectly by the bottom topography. The extent of the respective 

 influence varies daily. However, winds tend to dominate the currents at the 

 seaward end of the pier, whereas, the breaker angle and heights dominate 

 within the surf zone. During extreme wave conditions the seaward end of the 

 pier is within the breaker zone and, consequently, currents measured there are 

 strongly influenced by waves. The effect of the bottom topography is such 

 that under certain conditions rip currents develop which interrupt the general 

 flow of the longshore current. The trough under the pier is a preferred loca- 

 tion for such currents. This report concentrates on the longshore currents. 



49. Also measured were wave approach angles at the seaward end of the 

 pier, the breaker angle, and the breaker type nearshore. Wave direction was 

 also determined using a Raytheon Mariner's Pathfinder radar, manufactured by 

 the Raytheon Marine Company, Manchester, N. H., mounted on the roof of the FRF 

 building; use of this system for measuring ocean waves is explained by Mattie 

 and Harris (1978). 



Bathymetric and Pier Surveys 



Collection 



50. Profiles were obtained monthly and after storms by using the 

 Coastal Research Amphibious Buggy (CRAB), a 10.7-m-tall amphibious tripod, and 



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