Wind blowing over the ocean resonantly generates near-inertial waves (NIWs) which dominate the ocean kinetic-energy and vertical-shear spectra at frequencies above 0.2 cycles/day. Once generated, long-wavelength (low-mode) NIWs propagate long distances toward the equator before meeting an unknown fate, while short-wavelength (high-mode) NIWs persist for weeks under the storm track, maintaining ubiquitous upper-ocean shear. The exact partitioning between low- and high-mode NIWs is unknown, but relevant to ocean/climate feedback because breaking NIWs drive diapycnal mixing that affects the vertical transports of heat and carbon in the ocean. Low-mode NIWs are believed to scatter over rough topography where they may enhance deep boundary mixing. High-mode NIWs produce velocity shear associated with total kinetic energy dissipation through a variety of processes such as wave-wave or wave-mean interactions, thus contributing to open-water upper-ocean mixing. This project will synthesize existing NIW observations, theory, and numerical models to create a global NIW prediction system, which will help answer some basic questions that have persisted despite recent progress with theory and process studies: (1) How do dynamics in the ocean surface boundary layer (OSBL) shape NIW vertical wavenumber spectrum? (2) What is the fate of low-mode NIWs? and (3) How well do linearized models that include realistic wind, stratification, and mesoscale circulation predict upper-ocean shear? Resul