Environmental Science and Engineering Seminar

The ocean's subtropical gyres account for about half of the global flux of organic carbon sinking into the deep ocean. Biological production is limited by the availability of nutrients in these subtropical regions, because large-scale ocean circulation patterns push nutrient-rich waters away from the surface. The transfer of nutrients into the sunlit layer is achieved by fine-scale vertical nutrient transfers, at the expense of the layers beneath. We show that these sub-surface layers are replenished by the lateral turbulent transport of nutrients along density surfaces, on 10-100 km scales. This nutrient 'relay', involving both vertical and lateral transport, ultimately fuels biological production and sustains an associated sequestration of carbon in the subtropics.