Near-inertial wave propagation between stratified and homogeneous layers

The propagation of inertio-gravity waves (IGW) into the deep sea is relevant for energy transfer to turbulence where break, and thus redistribution nutrients, oxygen, suspended matter. In constant stratification, vertical IGW readily modelled. varying homogeneous layers alternate with stratified layers, transmission, reflection cause complex patterns. Half-year long moored acoustic Doppler current profiler (ADCP) observations midway between Balearic Islands Sardinia in 2800-m Western-Mediterranean Sea occasionally demonstrate a distinct transition, weakly (N ≥ 2f) ≤ f) at near-inertial frequencies. Here, N denotes buoyancy frequency f local inertial (vertical Coriolis parameter). transition stratification rather abrupt, within Δz = 25 m, provides an amplitude reduction 1.3 super-inertial motions. Simulations non-traditional momentum equations involving horizontal parameter fh qualitatively confirm observed refraction. observational area marked by variations hydrographic characteristics, abundant mesoscale eddies south dense-water formation north site during previous winter. Thus, also transitions occur from deeper, recently formed ones. Polarization spectra shear are bound IGW-limits related f, while polarization 2fh. These frequencies coincide large-scale independently various using shipborne CTD profiling.