step are used in IV2I while only the previous value of U^ is used in 

 V2. This implies that the coefficient of Ug on the left hand side of 

 (42) has to be changed from a constant value of 1 to 1 - 2.5 x 

 lO'-^CAt/D). However, the tridiagonal form of the coefficient matrix 

 is retained. 



At even time steps, coding for the bottom stress is obtained by 

 directly interchanging U and V to obtain 



T^ = 2.5 X 10~3At{[(l/D)Vg(I,J) - (l/H2)Vi(I,J)]2 



+ [(l/D)Ue(I,J) - (l/H2)Ui(I,J)]2}^{-(l/H2)v"(I,J)}. (55) 



The bottom stress for the internal mode computation is depicted as 



Tj3 = 2.5 X 10"-='At{[(l/D)Ug(I,J) - (l/H2)Ui(I,J)]' 



+ [(l/D)Vg(I,J) - (l/H2)VI,J)]2}^{(l/D)Ue(I,J)} (56) 



Tjj = 2.5 X 10"3At{[(l/D)Vg(I,J) - (1/H2)V^(I,J)]2 



+ [(l/D)Ug(I,J) - (l/H2)Ui(I,J)]2}^{(l/D)Vg(I,j)} (57) 



for odd and even time steps, respectively. 



-¥ 



The velocity vector W in the interface stress is the internal 

 mode volume transport per unit width multiplied by the appropriate 

 depth 



W = (D/HiH2)Qi (58) 



A constant value of 2.0 x 10"^ is assumed for the friction 

 coefficient, k. The finite difference form of this stress is, for 

 odd time steps, 



27 



