4 Wave and Water Level Data 



Wave height and period were collected as part of the routine collection program of the 

 FRF Measurements work unit. Wave height was computed as the energy-based significant 

 wave height H^„ defined as four times the standard deviation for a 34-min water level record 

 sampled at 2 Hz. Wave period Tp is defmed as the period associated with the peak in the 

 energy spectrum. Details of the measurement instruments and the digital data analysis are 

 available in the FRF Annual Data Summaries (e.g., Leffler et al. 1992). 



Wave height and period are tabulated every 6 hr in Appendix C. The majority of the 

 wave data are from gage 630, a waverider buoy located in the 18-m water depth directly off 

 the FRF research pier, rather than gage 625, which was used in the previous report (Howd 

 and Birkemeier 1987). Gage 625, a Baylor wave staff gage located at the seaward end of the 

 research pier, is in the surf zone during major storms and when the wave heights are 

 saturated, i.e., limited by wave breaking. The maximum wave height limit depends on water 

 depth but was usually under 3 m. This is not a problem with gage 630. To provide as 

 complete a record as possible, the data gaps in gage 630 were filled with wave data from two 

 pressure gages (gages 1 1 1 and 621) and from gage 625. The location and depth of the gages 

 used in this report are presented in Table 2. Note that when data from these additional gages 

 were inserted into Appendix C, they were not transformed to the depth at gage 630. 



The water level data were measured at a National Oceanic and Atmospheric Administration 

 (NOAA) tide station located at the end of the research pier. The data were recorded 

 instantaneously every 6 min. The data presented in Appendix D represent the total water 

 level variation including both the astronomical tides and storm surges (storm surge is defined 

 as the difference between the actual and predicted water level). The total water level should 

 give a better indication of possible forcing of profile change than would the predicted tides or 

 storm surge alone. Because of the voluminous amount of water level data, only plots of the 



Table 2 







Location and Depth of Wave Gages 











Distance Offshore 



Water Depth 



Gage Number 



Gage Type 



from Baseline 



m 



630 



Waverider Buoy 



6 km 



18 



111 



Pressure Gage 



1 km 



9 



621 



Pressure Gage 



600 m 



6 



625 



Continuous Wire Staff 



567 m 



8 



22 



Chapter 4 Wave and Water Level Data 



