ORCTM v2.0: implementation and evaluation of wave effects on currents based on the vortex-force formalism

Abstract. The Ocean Regional Circulation and Tide Model version 2.0 (ORCTM v2.0), which represents wave effects on currents (WEC) through online field exchange with SWAN via OASIS3-MCT, is presented. The configuration evaluated here is restricted to one-way wave-to-current forcing. The established vortex-force formulation is incorporated into ORCTM’s orthogonal curvilinear Arakawa C-grid, z-coordinate, partial-cell, and barotropic–baroclinic framework. It represents Stokes transport in the mass and free-surface equations; the Stokes–Coriolis force, vortex force, Bernoulli head, and wave-induced pressure contributions; and non-conservative momentum input associated with wave breaking, rollers, whitecapping, and surface and near-bottom streaming. SWAN bulk-wave and dissipation diagnostics are used to reconstruct the three-dimensional Stokes field and term-resolved WEC tendencies in ORCTM. The implementation is evaluated using an idealized plane-beach experiment with obliquely incident waves and the DUCK94 barred-beach experiment. These benchmarks examine wave-induced water-level adjustment, Stokes–Eulerian transport compensation, three-dimensional nearshore circulation, and momentum balances. The experiments demonstrate that ORCTM v2.0 can reproduce the principal nearshore WEC processes and provide process-resolved diagnostics of wave-induced mass and momentum pathways.