Interactions Between Physical Processes and Carbonate Chemistry in the Oceanic Mixed Layer

Ocean tracers such as carbon dioxide, play critical roles in the global carbon cycle and climate. These tracers evolve primarily in the oceanic mixed layer where gas exchange occurs and light is plentiful. There is substantial heterogeneity in tracer spatial distributions, and the effects of submesoscale turbulence remain incompletely understood, particularly in the sub-kilometer range. In this study, large eddy simulations are used to examine the effects of wind- and wave-driven turbulence, diurnal forcing, and wave breaking on carbonate chemistry in the oceanic mixed layer at submesoscales. Simulations are performed for various ocean conditions to determine the effects of these physical processes on the air-sea carbon dioxide flux and amount of total dissolved inorganic carbon. The wave-averaged Boussinesq equations are solved in the simulations using pseudo-spectral and finite difference methods in the horizontal and vertical directions, respectively. The carbonate chemistry system consists of seven reacting species and is solved using a second-order Runge-Kutta-Chebyshev integration scheme. Results are presented for the evolution and steady-state properties of each chemical species for the varied ocean conditions. Non-dimensional parameters based on chemical and mixing timescales are used to classify and parameterize the results. Implications of these results for Earth system models are outlined, and an outlook for future research directions is also provided.