Wave - current interaction model for up currents.

Two analytic models are developed to describe rip current cells on an open coastline with sloping planar foreshore and flat offshore bathymetry. Both models extend the work of LeBlond and Tang to include the refraction of the normally incident wave field by the nearshore circulation. The first model includes the effect of the currents on the incident wavelength, but no change in wave direction, and shows that no rip currents are possible. The second, more complete model considers the refraction of the waves as well and predicts rip current cells. The spacing of the rip currents and their associated variables are shown to be a function of one dimensionless parameter. Comparison of the predicted spacing with some published field data as well as with measurements obtained on the Isle of Sylt , West Germany, shows reasonable agreement with the second model. (A)