Understanding submesoscale tracer transport

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This project is a theoretical and computational process-oriented investigation of submesoscale tracer transport in the ocean. The work plan consists of two research activities, the first addressing submesoscale vertical transport by mixed layer instabilities at the ocean surface, and the second investigating the effects of internal waves on lateral stirring in the ocean interior. Submesoscale oceanic flows have been implicated in supplying nutrients to the surface ocean, in providing stratification that traps phytoplankton in the sun-lit surface layer and helps them bloom, and in subducting particulate organic carbon from the mixed layer into the ocean interior. The work will advance fundamental understanding of these processes and is crucial for improved predictions of how Earth's climate will evolve in the coming decades and centuries. The results of this work directly benefit the scientific community developing climate models, which currently do not represent submesoscale processes. The project supports a postdoc, a graduate student, and two undergraduate students who will be trained in physical oceanography.The project will explore how submesoscale flows transport tracers such as potential temperature, salinity, carbon, nutrients, and oxygen. In the first part of the proposed work, the mechanisms by which submesoscale baroclinic mixed layer instabilities subduct water into the thermocline and fold thermocline water into the mixed layer will be investigated. In the second part, a mismatch between theoretical predictions for the spatial structure of passive tracers in the thermocline and observations of such tracer distributions in the real ocean will be addressed. The hypothesis that internal waves have a leading-order effect on the observed tracer distributions will be explored.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.