Collaborative Research: Ocean Transport and Eddy Energy

Ocean mesoscale eddies are turbulent motions with lateral scales of tens to hundreds of kilometers. These eddies can significantly impact the transport of heat, carbon, and nutrients throughout the oceans, and play an essential role in shaping the ocean's strongest mean currents and their variability. Energy exchanged between the ocean and atmosphere, and across reservoirs and scales in the ocean controls the ocean circulation and transport. Mesoscale eddies play a significant role in this energy exchange. Yet, these eddies are at best partially resolved in ocean climate models, and most of their momentum and tracer transport must be parameterized. Imperfections in these parameterizations lead to biases in modern climate models, including incorrect rates of exchange of heat and carbon with the atmosphere, errors in the position and strength of the ocean's strongest current systems, and incorrect stratification at high latitudes. This Climate Process Team (CPT) brings together observationalists, modelers, and theoreticians to unify and extend recent research on ocean eddy energetics and parameterization, therefore improving both our knowledge of these processes and their representation in ocean models. Newly generated datasets for ocean energetics and transport, together with the increased fidelity of climate models, will advance our understanding of mesoscale eddies in the climate system in particular through their role in the energy budget. This research will lead to increased ocean model fidelity, and therefore has the potential to reduce some of the most stubborn biases in climate models, primarily related to the strength and position of strong currents, and the ocean's stratification. The team, which includes three leading global coupled modeling centers, will implement new parameterizations within climate models, therefore enhancing links between modeling centers and universities. The project will also generate new datasets and parameterizations, promoted on many platforms (e.g., Pangeo, GitHub), which can be used by the whole climate community. The results will be disseminated via publications and annual workshops involving the international community. The project will support the training of four postdoctoral researchers by enhancing their knowledge in fundamental ocean dynamics, eddy parameterizations, numerical modeling, and observational analysis. The team will also promote underrepresented groups in STEM (three female PIs, including the lead PI). Finally, improved climate simulations can lead to improved predictions with significant societal and economic benefits.

Extant parameterizations fail to fully account for the exchanges of mesoscale energy with different scales, or conversions between kinetic and potential energy reservoirs. Recent advances from theory, process studies and longer-term observational records of ocean energetics can now be leveraged to improve the current generation of climate models across a range of horizontal resolutions. This CPT aims to vet, improve, and unify new advances in energy-, flow- and scale-aware eddy parameterizations in process studies and global models; constrain parameters and parameterized eddy fluxes through a synthesis of up-to-date observations of ocean energetics and transport; and implement and assess schemes within IPCC-class models at NCAR, GFDL, and LANL. Modernized, energetically-consistent mesoscale eddy parameterizations are expected to significantly reduce model biases in ocean currents, stratification, and transport.

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.