and 



T = 8.6 e 

 s 



RAp 

 9400 



0.145 a V, 



1 + 



Vu7 



metric units 



(3-60a) 



T = 8.6 e 

 s 



RAp 

 200 



0.104 a V^ 



1 + 



V^ 



English units 



(3-60b) 



where 



R 



Ap 



U 



'/? 



= deepwater significant wave height in meters (feet) 



= the corresponding significant wave period in seconds 



= radius of maximum wind in kilometers (nautical miles) 



= p^ - p- , where p^ is the normal pressure of 760 millimeters 



(29.92 inches) of mercury, and p^ is the central pressure of the 

 hurricane 



= The forward speed of the hurricane in meters per second (knots) 



= The maximum sustained windspeed in meters per second (knots), 



calculated for 10 meters (33 feet) above the mean sea surface at 

 radius R where 



Up = 0.865 ^mn~. (for stationary hurricane) 



"max 



(3-61) 



U, 



max 



U^ = 0.865 U^yj^^ + 0.5 V^? (for moving hurricane) 



Maximum gradient windspeed 10 meters (33 feet) above the 

 water surface; i.e., 



U„„„ = 0.447 [14.5 (p - P-)^^^ - R(0.31f)] 



(3-62) 



max 



^rmx = 0-868 [^3 (p^ - p^)^^^ - R(0.575f)] 



metric units 

 (3-63a) 



English units 

 (3-63b) 



Coriolis parameter = 2a) sincj) , where o) = angular velocity of 

 Earth = 2it/24 radians per hour 



a 



Latitude ( (|>) 

 f (rad/hr) 



25° 30° 35° 40° 

 0.221 0.262 0.300 0.337 



a coefficient depending on the forward speed of the hurricane and 

 the increase in effective fetch length because the hurricane is 

 moving. It is suggested that for a slowly moving hurricane a 

 = 1.0 . 



3-84 



