Wow this is complicated...

MOVIE ADDED. CLICK HERE.

So I'm still looking for the 'forcing' to correlate with the vorticity response that we are seeing. Against the advice of my advisor I was still trying with the complicated ('real-life') scenario. I took a transect over the bar crest and tried to compare the vorticity there with the alongshore wave height gradient at that transect as well as with the wave height just offshore of breaking. Here's a plot that shows 5 of thos comparisons ranging from 2 min in the simulation to 35 min. For the first time (when vortical strucutres are initally being formed) its relates VERY well to dH/dy (green and black lines). BUT as time goes on and these vortices travelled alongshore this isn't the case. Strong vortices that move alongshore are still 'surviving' I think but they are no longer associated with the waves travelling above them at the water surface. So now we need to look at not only their initial forcing but the dynamics of the vortices themselves in a 'free' system?

SO the moral of the story is...listen to your advisor. Time to step back and look at a simpler case again and see if we can sort any of this out.

I also posted a new f-ky spectra plot that includes one for the offshore wave height. It is bounded in the range we were hoping for (at least at this color scale) but I have energy in the lowermost frequency bin which doesn't match Reniers et al.