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2021WP/VLD-03_Aimie_Moulin_Wave_Coupling_TestCase – NEMO

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Action NEMO-Wave coupling test case
PI(S) Aimie Moulin, Emanuela Clementi
Digest An adiabatic test case will be implemented to test the NEMO-wave interactions consisting of a steady monochromatic wave shoaling on a slope without bottom friction. A symmetric bottom sloping is used to allow for periodic boundary conditions in the x-direction. Open boundary conditions are defined in y-directions.
Branch source:/NEMO/branches/{YEAR}/dev_r{REV}_{ACTION_NAME}
Previewer(s) Rachid Benshila
Reviewer(s) TBD
Ticket #2613


The adiabatic test case is used to validate the implementation of the GLM equation in case of wave-current interaction.
It consists on a steady monochromatic waves shoaling from 4 to 6 m depth on a slope without breaking nor bottom friction nor wave-induced mixing, and for an inviscid fluid.
Waves and bottom topography are uniform in the y_direction. The flow is confined to a channel with free-slip boundary condition at North and South.
Open boundary condition are set at the East and West. 120 sigma-levels are used.

In this testcase NEMO is forced by wave fields calculated by WaveWatch3.
The characteristics of the waves are a significant wave height Hs=1.02m, a wave period T=5.26s, and a wave direction theta=90°.

In absence of dissipation, and given proper lateral boundary conditions the flow in wave shoaling over a bottom slope has to be irrotational.
The reference solution exhibit a vertical shear that is entirely due to the Stokes drift and the quasi-Eulerian velocity is homogeneous over the water column.


  1. Ardhuin, N. Rascle and K. Belibassakis,2008, Explicit wave-averaged primitive equations using a Generalized Lagrangian Mean, Ocean Modelling

A.C. Bennis and F. Ardhuin, 2011, Comments on ‘ The Depth-Dependent Current and Wave Interaction Equations: A Revision ’, JPO


No changes in NEMO code

usrdef_nam.F90, usrdef_hgr.F90, usrdef_zgr.F90, usrdef_sbc.F90, usrdef_istate.F90

Documentation updates

Updates needed for the online documentation:

The test case is in pull request in the NEMO-examples github page


Error: Failed to load processor box
No macro or processor named 'box' found

I totally agree on the methodology, including the choices of forcing by WWIII offline, instead of coupling, in a sake of simplicity. References are provided, and the results show the test case has been completed.

The main question raised by the developers, in term of practical implementation, is the way to integrate the alternative profile for Stokes drift computation, at least at short term, with 2 suggestions:

a) include an additional Stokes Drift profile parameterization in sbcwave.F90, in the tescase MY_SRC. The formulation for the Stokes drift decay should be the one from Michaud et al, 2012 for intermediate/shallow water.

b) add a userdef parameterization for the vertical Stokes drift in OCE/USR/ folder.

Solution b) could me more logical, but a eventually a bit "too much" for something which may not be changed a lot by users for other cases. So I would suggest solution a), and discuss at some point for next releases the inclusion of this option in the standard sbcwave.


Error: Failed to load processor box
No macro or processor named 'box' found



Error: Failed to load processor box
No macro or processor named 'box' found

It has been reviewed by Rachid Benshila: I didn’t find any problem in the implemntation, it runs fine. It’s super minor, there was one typo in the namelist, nn_fsbc as a real instead of an integer.

Last modified 7 months ago Last modified on 2021-11-22T17:10:38+01:00

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