open TELEMAC-MASCARET The mathematically superior suite of solvers

I’m trying to set up a simple Tomawac model over the southern part of Baltic Sea. I’m using a grid of 5 000 m and my time step is 60 s. I want to use this larger model as input for a smaller more detailed model of a certain coast stretch and where I want to estimate the longshore transport rate along a beach. (I’m attaching the cas-file)

However with the larger model I get very low wave heights when including the default parameters for bottom friction, white capping and depth induced breaking. I’m attaching a results (see fig1.png) from a simulation of one month where I compare model results with wave losses (friction, white capping, breaking) with measured results from a wave buoy. The wave buoy is located where the depth is 110 m. As you can see the waves are too small when including the wave loss paramaters but are better described when not including any wave loss parameters. Also when looking at the wave period it is too small (see fig2.png). However in order to estimate the longshore transport I want to include the depth induced breaking since this is important for the nearshore transport.

I also made a test for a constant wind of 15 m/s. According to SPM the Hmo should be about 4,5 m at the point where I extracted the wave series from the model. (the depth at this point is 80 m and fetch about 235 km). My test included running the model with the different wave loss parameters solo and combined. As you can see in fig3.png the white capping and depth induced breaking reduces the wave height with about 6 m.

So my questions are:
-Why does the white capping and depth induced breaking have such big impact on my results?
-Which parameters should I use to adjust the model results to better reflect the measurements?

Best regards
//Björn