  The nonlinear dynamics of waves at the sea surface is believed to be ruled by
the Weak Turbulence framework. In order to investigate the nonlinear coupling
among gravity surface waves, we developed an experiment in the Coriolis
facility which is a 13-m diameter circular tank. An isotropic and statistically
stationary wave turbulence of average steepness of 10\% is maintained by two
wedge wave makers. The space and time resolved wave elevation is measured using
a stereoscopic technique. Wave-wave interactions are analyzed through third and
fourth order correlations. We investigate specifically the role of bound waves
generated by non resonant 3-wave coupling. Specifically, we implement a
space-time filter to separate the dynamics of free waves (i.e. following the
dispersion relation) from the bound waves. We observe that the free wave
dynamics causes weak resonant 4-wave correlations. A weak level of correlation
is actually the basis of the Weak Turbulence Theory. Thus our observations
support the use of the Weak Turbulence to model gravity wave turbulence as is
currently been done in the operational models of wave forecasting. Although in
the theory bound waves are not supposed to contribute to the energy cascade,
our observation raises the question of the impact of bound waves on dissipation
and thus on energy transfers as well.
