S phase of a single progressive wave train (eq. 9) 



5 „ radiation stress tensor (eq. 21) 

 T wave period 



T time scale of a current (eq. 1) 



t time 



u, u current velocity (magnitude and vector) 



u amplitude of oscillating current velocity (eq. 1) 



u(x)i unidirectional current in the positive x direction 



u(z) current varying in the vertical (z) direction (see eq. 7) 



u ,Un oscillatory horizontal (u^^ ) and vertical (ug) particle 

 velocities due to wave motion (eqs. 17 and 21) 



V(x)j unidirectional current in the positive y direction 



X position vector (eq. 8) 



X distance coordinate in a direction (eqs. 11 and 17) 



xi, Xo rectangular coordinate directions (eqs. 10 and 12) 



z vertical distance (eq. 7) 



a suffix indicating component in the a direction 



6 phase angle 



6 „ Kronecker delta; 1 when a = g and when a ^ B (eq. 21) 

 Otp 



T\ free-surface elevation above water level 



9 angle between u and k 



■n constant = 3. 14159 



p mass density of water 



O wave radian frequency relative to the current 

 (see eqs. 3 and 4) 



T, mean bottom stress (eq. 27) 



V gradient of a scalar (first partial derivatives) as in 

 equations (2), (10), etc. 



0) wave radian frequency (eq. 3) 



