Modeling Ocean Uptake in an idealised Southern Ocean

Nov. 2, 2018
High resolution simulations show the convoluted pathways of tracer transport along "tracer curtains", which form from surface to depth along fronts and eddies.
The Earth's oceans store large reservoirs of carbon dioxide, oxygen, and other biogeochemical tracers in the subsurface water column—about 30% of the anthropogenic CO2 produced in the industrial era has been sequestered in the ocean (Figure TS.4 in IPCC AR 5). Eddies and fronts - ocean weather - are important for this uptake, but due to their small spatial scales  (1–100 km)  have to be parameterized in the ocean component of climate models. The Southern Ocean is recognized to be a major sink for anthropogenic CO2, but also has the largest uncertainty between models due to reliance on parameterizations of these small scale processes. 
 

Dhruv Balwada and Shafer Smith at CAOS, in collaboration with Ryan Abernathy at Columbia University, have investigated the role of eddies and fronts in tracer (eg. CO2) uptake using an idealized model of the Southern Ocean. The model resolution is varied as a means to include or omit turbulent processes at various scales. The study finds that the submesoscale‐permitting simulations flux far more tracer downward than the lower‐resolution simulations. They also find that inertia‐gravity waves, which are ubiquitous in the ocean and are generally associated with very strong vertical velocities, had little impact on the tracer uptake. This work provides guidance and potential paths forward for improving fidelity of current generation climate simulations.