Geometric phases of water waves

Recently, Banner et al. ( Phys. Rev. Lett. , 112 (2014) 114502) highlighted a new fundamental property of open ocean wave groups, the so-called crest slowdown. For linear narrow-band waves, this is related to the geometric and dynamical phase velocities U d and U g associated with the parallel transport through the principal fiber bundle of the wave dynamics with U (1) symmetry. The theoretical predictions are shown to be in fair agreement with ocean field observations, from which the average crest speed with and .