Large-scale vorticity generation due to dissipating waves in the surf zone

In this paper, we investigate the mechanisms which control the generation ofwave-induced mean current vorticity in the surf zone. From the vertically-integratedand time-averaged momentum equations given recently by Smith [21],we obtain a vorticity forcing term related to differential broken-wave energy dissipation.Then, we derive a new equation for the mean current vorticity, from the nonlinear shallowwater shock-wave theory. Both approaches are consistent, under the shallow water assumption,but the later gives explicitly the generation term of vorticity, without any ad-hoc parametrizationof the broken-wave energy dissipation.