1.3 

 1.2 



^7:-=^^^ 



I.I 



i\ 



Rj 1.0 

 0.9 



1 1 



Example 2 



0.8 

 07 



1 1 1 ._.I 1 1 1 



-20 -15 -10 -5 5 10 15 20 

 Air-Seo Temperature Difference (Tq— Tj) "C 



Figure 4. Amplification ratio, Rj, accounting for effects of air-sea 

 temperature difference (Reslo and Vincent, 1976). 



IV. EXAMPLE PROBLEMS 



*************** EXAMPLE PROBLEM 1*************** 



GIVEN ; Deepwater fetch, F = 24.9 miles (40 kilometers), adjusted 33-foot (10 

 meter) windspeed, Ua = 65.6 feet (20 meters) per second (an example of com- 

 putation of the adjusted windspeed can be found in U.S. Army, Corps of 

 Engineers, Coastal Engineering Research Center, 1981). 



FIND ; Significant wave height and peak period of the wave spectrum at depths 

 of 23 and 9.8 feet (7 and 3 meters). 



SOLUTION ; The dimensionless fetch, x is 



_ gF (9.8 m/s^) (40,000 m) 



U, 



(20 m/s)' 



980 = 9.8 X lo2 



The deepwater significant wave height and peak period are 



Ho = 1.6 X 10 



-3 



Ua 



= 1.6 X 10-3 J ^^1^1^ (20 m/s) = 2.04 mete 



Tr. = 



Uax ^/3 20(980) "^/^ 



P 3.5g 3.5(9.8) 

 at a depth of 7 meters 



d 7 



5.79 seconds 



Ho 2.04 



= 3.43 



