Effects of Langmuir Turbulence on Upper Ocean Carbonate Chemistry. (12th December 2018)

• Record Type: Journal Article
• Authors: Smith, K. M.; Hamlington, P. E.; Niemeyer, K. E.; Fox‐Kemper, B.; Lovenduski, N. S.
• Is Part Of: Journal of advances in modeling earth systems. Volume 10:Number 12(2018)
• Page Start: 3030
• Page End: 3048
• Publication Date: 2018-12-12
• Subjects: Geological modeling -- Periodicals; Climatology -- Periodicals; Geochemical modeling -- Periodicals; 551.5011
• DOI: 10.1029/2018MS001486
• Languages: English
• ISSNs: 1942-2466

Abstract

Abstract: Effects of wave‐driven Langmuir turbulence on the air‐sea flux of carbon dioxide (CO2 ) are examined using large eddy simulations featuring actively reacting carbonate chemistry in the ocean mixed layer at small scales. Four strengths of Langmuir turbulence are examined with three types of carbonate chemistry: time‐dependent chemistry, instantaneous equilibrium chemistry, and no reactions. The time‐dependent model is obtained by reducing a detailed eight‐species chemical mechanism using computational singular perturbation analysis, resulting in a quasi steady state approximation for hydrogen ion (H + ); that is, fixed pH. The reduced mechanism is then integrated in two half‐time steps before and after the advection solve using a Runge‐Kutta‐Chebyshev scheme that is robust for stiff systems of differential equations. The simulations show that as the strength of Langmuir turbulence increases, CO2 fluxes are enhanced by rapid overturning of the near‐surface layer, which rivals the removal rate of CO2 by time‐dependent reactions. Equilibrium chemistry and nonreactive models are found to bring more and less carbon, respectively, into the ocean as compared to the more realistic time‐dependent model. These results have implications for Earth system models that either neglect Langmuir turbulence or use equilibrium, instead of time‐dependent, chemical mechanisms. Key Points: Detailed carbonate chemistry is solved in large eddy simulations of upper ocean turbulence Langmuir turbulence increases the air‐sea flux of CO2, resulting in increased dissolved inorganic carbon Equilibrium chemistry leads to overpredicted fluxes of CO2 into the upper ocean