Modeling Heat and Carbon in the Argentine Basin

Abstract

We construct regional ocean circulation models with biogeochemistry with eddy-permitting (1/3 degree) to eddy-resolving (1/12 degree) resolutions to investigate heat and carbon dynamics in the region and determine the effect of model resolution on these dynamics. Simulations of the Argentine Basin have large uncertainties associated with quantities such as air-sea exchanges of heat and carbon in current generation climate models and ocean reanalysis products. This is due to the complex topography, profound undersampling, and strong currents and mixing of subpolar and subtropical water masses in the basin. Because mixing of water masses is important here, model resolution is hypothesized to play an important role in estimating ocean quantities and determining overall budgets. The implemented models are evaluated for fidelity by comparing output to a variety of observational datasets and reanalysis products. We then quantify the effect of resolution on model upper ocean heat and carbon transport and the associated air-sea exchanges and determine that higher resolution models have increased upward heat transport and surface heat fluxes, but no significant effect is observed for carbon. Then, the forecast horizon for ocean surface quantities of temperature and carbon is probed by using these same regional models at two resolutions and designing a series of wind stress perturbation experiments. We calculate the responses of the surface temperature and dissolved inorganic carbon and estimate the forecasting capability of each resolution. We show that responses in the 1/12 degree model are approximately linear and decay for 1-2 weeks. For the 1/3 degree model this increases to 4-6 weeks, but it is only consistent with the 1/12 degree forecast for about one week which shows the diminished potential predictive skill of the coarser model.