Gravity wave turbulence in wave tanks: space and time statistics.

We present the first simultaneous space-time measurements for gravity wave turbulence in a large laboratory flume. We found that the slopes of k and omega wave spectra depend on wave intensity. This cannot be explained by any existing theory considering wave turbulence as the result of either breaking events or weakly nonlinear wave interactions. Instead, we show that random waves and breaking or coherent structures appear to coexist: The former show themselves in a quasi-Gaussian core of the probability density function and in the low-order structure functions, and the latter in the probability density function tails and the high-order structure functions.