IV. ENVIRONMENTAL CHARACTERISTICS 



This section summarizes available environmental data and information use- 

 ful for planning studies at the FRF. 



1. General Weather. 



The FRF has a favorable marine climate with mild winters and warm temper- 

 ate summers. The nearest weather stations with long periods of record are 

 Cape Hatteras, North Carolina, and Norfolk, Virginia. Table 5 provides a NOAA 

 summary of the normal, mean, and extreme meteorological data for each of these 

 stations. More detailed information including monthly summaries and three- 

 hourly measurements can be obtained from: 



Environmental Data and Information Service 

 The National Climatic Center 

 Federal Building 

 Asheville, NC 28801 



Figure 13 is a plot of monthly wind roses compiled from 1,853 observations 

 at Sea Crest, North Carolina, 5 kilometers (3 miles) south of the FRF (see 

 Fig. 1), using a hand-held Dwyer wind meter, from January 1972 to December 

 1978. Note the predominant winds from the northeast and southwest with the 

 highest percentage of strong winds from the north and northeast. Wind distri- 

 bution varies considerably from month to month. 



2. Waves . 



a. Ocean. Thompson (1977) summarized the wave climate for the area using 

 measurements collected by a wave gage on Jennette's Fishing Pier (Fig. 11) 

 from December 1968 to January 1975. This data set has been updated to include 

 measurements to December 1979. 



Figure 14 shows the seasonal variation in mean and standard deviation of 

 the monthly wave height and period. Peak waves occur in October and February. 

 Joint monthly distributions of significant wave height and period distribu- 

 tions are given in Appendix D. Table 6 is a summary of the distribution for 

 the entire period, indicating the mean average wave height is 0.88 meter (2.9 

 feet) and the mean period is 8.9 seconds. Higher waves have been measured in 

 the deeper water at the FRF. Figure 15 shows wave action during an October 

 1980 storm when the significant wave height reached 3.8 meters (12.5 feet). 

 Measurements have also been made of breaking waves. Average monthly values 

 for 7 years of observations at Sea Crest are shown in Figure 16. 



The only historic wave direction information available is taken from LEO 

 observations. Wave roses are shown in Figure 17. Predominant wave directions 

 are shore normal (90°) and just right of shore normal (90° to 95°). Waves 

 tend to approach the shore from the right in summer and from the left in the 

 winter. 



b. Sound . Because of the limited fetch across Currituck Sound, waves on 

 the sound shore are usually an irregular chop of less than 15 centimeters (0.5 

 foot). The average fetch is 7.3 kilometers (4.4 miles); the longest fetch is 

 8.9 kilometers (5.3 miles). The sound is extremely shallow and gently sloping 

 (less than 1 percent). The deepest areas, which average only 2.7 meters (9 

 feet) in depth, are on the western shore. Wave heights and setup during 

 extreme events have not been documented. 



36 



