Model constraints on the anthropogenic carbon budget of the Arctic Ocean

Abstract

Abstract. The Arctic Ocean is projected to experience not only amplified climate change but also amplified ocean acidification.Modeling future acidification depends on our ability to simulate baseline conditions and changes over the industrial era. range from a previous data-based C ant storage estimate (2.5 to 3.3 Pg C). Yet those limits may each need to be reduced by 10 about 10% because data-based C ant concentrations in deep waters remain at ∼6 µmol kg −1 , while they should be almost negligible by analogy to the near-zero observed CFC-12 concentrations from which they are calculated. Across the three resolutions, there was roughly three times as much anthropogenic carbon that entered the Arctic Ocean through lateral transport than via the flux of CO 2 across the air-sea interface. Wider comparison to nine earth system models that participated in the Coupled Model Intercomparison Project Phase 5 (CMIP5) reveals much larger diversity of stored anthropogenic carbon and 15 lateral transport. Only the CMIP5 models with higher lateral transport obtain C ant inventories that are close to the data-based estimates. Increasing resolution also enhances acidification, e.g., with greater shoaling of the Arctic's average depth of the aragonite saturation horizon during 1960-2012, from 50 m in ORCA2 to 210 m in ORCA025. To assess the potential to further refine modeled estimates of the Arctic Ocean's C ant storage and acidification, sensitivity tests that adjust model parameters are needed given that century-scale global ocean biogeochemical simulations still cannot be run routinely at high resolution.

Quantification of Chaotic Intrinsic Variability of Sea‐Air CO2 Fluxes at Interannual Timescales

“…The carbon chemistry is computed following recommendations of Phase 2 of the Ocean Carbon-Cycle Model Intercomparison Project (OCMIP) (Najjar & Orr, 1999). The model considers three external sources of nutrients: river input, atmospheric deposition, and sediment mobilization for Fe (Terhaar et al, 2018).…”

Evaluation of an Online Grid‐Coarsening Algorithm in a Global Eddy‐Admitting Ocean Biogeochemical Model

“…Despite its importance for both ocean and biogeochemical dynamics, the influence of mesoscale activity on ocean biogeochemical cycles has been identified as a missing process in the current generation of Earth system models as assessed in IPCC AR5 (Fifth Assessment Report of the Intergovernmental Panel on Climate Change; Ciais et al, 2013). For example, Terhaar et al (2018) recently show that the Arctic Ocean storage of anthropogenic carbon differs when moving from coarse to eddy-admitting resolution in a global ocean circulation-biogeochemistry model. Indeed, theory of flow dynamics suggests that a few kilometers of horizontal resolution is needed to enable global ocean biogeochemical general circulation models (OBGCMs) to resolve eddies and their interactions with submesoscale dynamics.…”