open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello,
I have a problem with my Tomawac results when I use the coupling system Telemac2D/Tomawac.
In the attached file, you can see the results of my simulations in terms of significant wave height (in red without coupling, in orange for Tomawac coupled with Telemac).

My time steps are :
- 30 s for Telemac
- 30 s for Tomawac
- a coupling period of 1

The results of Telemac in terms of current are good (by confrontation with obseravtions). It's the same for results of Tomawac.

Does someone have an idea of why the oscillations created by coupling are so high?
Thanks
Amandine