During the peak of the 5.4-m wave event in March 1996, the waves were depth limited 

 across the entire ebb shoal and near-inlet region. The height decreased 20 percent between 

 the offshore and ebb shoal gauges and an additional 40 percent between the ebb shoal and 

 inlet throat gauges at the peak of the event. This storm was numerically modeled for 

 validation of wave and circulation models by Smith, Militello, and Smith (1998). In the 

 6 months of analysis, there are five events with wave heights exceeding 2 m. Some of 

 these events are short in duration (e.g., the 5 September 1997 event, with a peak height of 

 2.3 m, exceeded 1 m in height for 3 days (Figure 14)). Others are much longer (e.g., the 

 1 1 October 1997 event, with a peak height of 2 m, exceeded 1 m in height for 1 1 days 

 (Figure 15)). As expected, the large wave events are highly correlated to strong local 

 winds. 



Wave period 



Peak wave periods from the three gauges for the three time periods are shown in 

 Figures 16-27. The measured periods ranged from 3 to 21 sec. Generally, the peak 

 periods are consistent from gauge to gauge for each time period and vary slowly with time. 

 However, the difference in wave period between two gauges or between 2 hr at one gauge 

 may vary by as much as 5 sec. These large variations typically occur at times when there 

 are multiple frequency peaks in the spectra. This is evident in the frequency spectra for 

 28 August 1996 at 1800 Greenwich Mean Time (GMT), shown in Figure 28. The lower 

 frequency peak (16-sec period) dominates at the offshore gauge, and the low-frequency 

 peak becomes larger at the ebb shoal gauge due to shoaling and remains dominate. In the 

 outer inlet throat, the higher frequency peak (9-sec period) dominates, due to refraction and 

 possibly sheltering by the north jetty. Jumps in the peak period also occur at times with 

 very low wave energy. Also, the high-frequency cutoff is different at each gauge because 

 of the different water depths. 



Wave direction 



Peak wave directions from the three gauges for the three time periods are shown in 

 Figures 29-40. The figures give the peak spectral direction from which the waves 

 propagate, relative to true north. The wave direction normal to offshore depth contours at 

 Ponce de Leon Inlet is about 60 deg. The average wave direction for the 6 months of data 

 was approximately 70 deg. Most of the large wave events have north or northeast wave 

 directions. At the offshore and ebb shoal gauges, the wave direction often varies by 5 to 

 10 deg from hour to hour. The variability at the inlet throat gauge is higher with hour-to- 

 hour oscillations of 10 to 20 deg. Greater variability in wave direction (similar to the 

 variability in wave period) is seen in some cases with multiple wave trains or cases with 

 very low wave energy. 



Chapter 3 Example Results and Discussion 1 7 



