Séminaire Severine Atis

Internal Gravity Waves in Periodic Stratifications

In the presence of gravity, fluids naturally stratify by density. The interplay between heat and salt diffusion in seawater can lead to periodic stratification profiles known as thermohaline staircases. Although observed in the ocean, their effects on internal gravity wave dynamics have remained unclear. We report experimental observations of band gaps for internal waves in a laboratory setup with periodic stratification. We find surface states with frequencies within the band gap, exponentially localized near interfaces and controlled by boundary conditions. These surface states are formally equivalent to those in one-dimensional topological insulators and photonic crystals. Our findings suggest that the presence of periodic stratifications in the ocean could significantly alter energy transport by internal waves.