where o)p/dx and dp/dy represent average values of the horizontal 

 pressure gradients in the whole layer between z = -D and z = 0. 



The two integrals in equations (6) are equal to the differences 

 of the components of the tangential stress at the surface and at 

 the depth -D, The tangential stress at the surface can be evalu- 

 ated from the wind at "anemometer height" by means of an empirical 

 formula (Neumann, 1948). This question, however, needs some further 

 consideration and will be discussed in more detail in section IX 

 of this report. The tangential stress in the depth z = -D equals 

 zero. 



Besides the wind stress at the surface, horizontal and vertical 

 shearing stresses in the water have to be taken into account. The 

 dynamical effect of these internal stresses is evident in the vir- 

 tual internal friction. Since it is difficult to introduce internal 

 friction in a most general form, and in order to simplify the dif- 

 ferential equations for the mathematical analysis, it seems justi- 

 fiable for the purpose of the present report to assume that the 

 frictional forces are proportional to the total mass transport M. 

 The combined effect of the virtual friction in horizontal and verti- 

 cal direction will be considered as an "effective" internal friction. 

 For the whole water column between z = -D and z = the components 

 of the effective internal frictional forces are assumed to be 



(7) 



where r[sec~ ] represents an effective "friction"-coeff icient. A 

 plausible average value of this coefficient has to be determined 

 later, 



10 



