in a stably stratified ocean, water that is displaced vertically from its equilibrium position will feel a restoring force that is proportional to the magnitude of the displacement. associated with this restoring force is a natural frequency of oscillation known as the brunt-vasiala frequency az where n is the brunt-vaisala frequency, g is the acceleration due to gravity, ρ is the density of the displaced water. derive this equation for n2. you could start by writing down the one-dimensional equation for motion for the vertical displacement of a water element displacement downward in a density stratified fluid and recall equations for simple harmonic motion.