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A. 5 Depths of Validity 



As the method is very similar to Stokes theory, it is expected to be valid in a similar 

 range of depths. Stokes theory is valid if both e and the parameter, e/{kh)^, similar 

 to the Ursell number, are small (Fenton 1985a). This indicates that the method has 

 optimal applicability in deep water, and should not be applied in shallow water. 



