Mixed-layer diapycnal fluxes in the Caribbean Sea and the western tropical Atlantic

Nitrogen compounds play an important role in atmospheric and biogeochemical processes. Nitrous oxide (N₂O) is recognized as a potent greenhouse gas and an intermediary in the destruction of stratospheric ozone, as well as a source of tropospheric ozone. The supply of nitrate in the mixed layer is directly related to primary productivity. The application of the TOMS hydrodynamic mixed layer model allows the quantitative exploration of diapycnal fluxes of nitrous oxide and nitrate in this dynamically complex region of the Atlantic Ocean. A better knowledge of circulation elements in the Intra-Americas Sea (IAS): such as eddies and recirculating features, dispersal mechanisms, upwelling and downwelling zones and events, and space and time scales of mesoscale variability was required before attempting to tackle research topics in the air-sea exchange of trace gases and the dispersion of riverine plumes.; High correlation was identified between the shear velocity field and diapycnal diffusivity field in the Caribbean and equatorial regions. Four categories of strength of vertical mixing and diapycnal gas flux were identified. Vast regions of non-significant mixing activity (values close to the background diffusivity, 1.0 × 10−4 m2s −1) are located around the subtropical gyre in the North Atlantic. Low and medium activity are found in the north and central Caribbean (from 1.05 × 10−4 to 2.2 × 10−4 m2s−1) whereas; high activities are located in the south Caribbean (from 2.0 × 10−4 to 3.3 × 10−2 m2s−1). Estimates from the model agree with reported high values of vertical mixing coefficients for the eastern Caribbean region.; Nitrate flux estimates for low latitudes are in agreement with others estimates found in the literature. High values of nitrous oxide fluxes were found by the model in agreement with previous observational data reported for three stations close to Puerto Rico.