D2 
Peak Spectral Wave Period Distributions 
Annual and monthly peak wave period 7., distribution histograms for 1994 
are presented in Figures D5 and D6. Data for 1980 through 1994 are present- 
ed in Figure D7. 
Persistence of Wave Heights 
Table D5 shows the number of times in 1994 when the specified wave 
height was equaled or exceeded at least once during each day for the duration 
(consecutive days). Data for 1980 through 1994 are averaged and given in 
Table D6. An example is shown below: 
Height Consecutive Day(s) or Longer 
m 12 Sea SC are OF 
24 21 18 14 
8 
0. 
1. 
1. 
as 
2. 
Be 
3. 
4. 
This example indicates that wave heights equaled or exceeded 1.0 m 
50 times for at least 1 day; 34 times for at least 2 days; 24 times for at least 
3 days, etc. Therefore, on 16 occasions the height equaled or exceeded 1.0 m 
for 1 day exactly (50 - 34 = 16); on 10 occasions for 2 days; on 3 occasions 
for 3 days, etc. Note that the height exceeded 1 m 50 times for 1 day or 
longer, while heights exceeded 0.5 m only 18 times for this same duration. 
This change in durations occurred because the longer durations of lower 
waves may be interspersed with shorter, but more frequent, intervals of higher 
waves. For example, one of the times that the wave heights exceeded 0.5 m 
for 16 days may have represented three times the height exceeded 1 m for 
shorter durations. 
Spectra 
Monthly spectra for the offshore staff gauge (Gauge 625) are presented in 
Figure D8. The plots show "relative" energy density as a function of wave 
frequency. These figures summarize the large number of spectra for each 
month. The figures emphasize the higher energy density associated with 
storms, as well as the general shifts in energy density to different frequencies. 
Appendix D Wave Data for Gauge 625 
