Intra-Annual Rossby Waves Destabilization as a Potential Driver of Low-Latitude Zonal Jets: Barotropic Dynamics

Abstract At low latitudes in the ocean, deep currents are shaped into narrow jets flowing eastward and westward, reversing periodically with latitude between 15°S 15°N. These present from thermocline to bottom. The energy sources physical mechanisms responsible for their formation still debated poorly understood. This study explores role of destabilization intra-annual equatorial waves jets’ process, as these known be an important source at latitudes. focuses particularly on barotropic Rossby a first step toward understanding relevant mechanisms. It is shown set idealized numerical simulations analytical solutions that nonlinear triad interactions (NLTIs) play crucial transfer jet-like structures (long short meridional wavelengths) induce zonal residual mean circulation. sensitivity instability emergence scale selection secondary wave forced primary analyzed. For realistic amplitudes around 5–20 cm s ?1 , produce most zonally propagating periods 60 130 days wavelengths 200 300 km. NLTI mechanism generation permanent jet-structured circulation discussed context turbulent cascade theories.