Development of the Regional Carbon Cycle Model in the Central Pacific Sector of the Southern Ocean

• Main Author: Ito, T. (Author)
• Format: Article
• Language: English
• Published: John Wiley and Sons Inc 2022
• Subjects: Antarctic; Biogeochemicals; Biogeochemistry; carbon cycle; Carbon cycle models; Carbon cycles; Carbon dioxide; Climate models; Earth system models; Fracture zone; Iron biogeochemistries; Ocean currents; Ocean model; ocean modeling; Pacific sector; Regional modelling; Southern ocean; Southern Ocean; Surface waters
• Online Access: View Fulltext in Publisher

 This study develops a new regional model of the Southern Ocean including an improved representation of the iron biogeochemistry and ecosystem component, nesting within a biogeochemical ocean state estimate, and benchmarking with a suite of observations. The regional domain focuses on the Udintsev Fracture Zone (UFZ) in the central Pacific sector of the Southern Ocean. The UFZ is characterized by the deep gap between the Pacific-Antarctic Ridge and the East Pacific Rise, which is one of the key “choke points” of the Antarctic Circumpolar Current where major Southern Ocean fronts are constrained within close proximity to this topographic feature. It is also a region of elevated mesoscale eddy activity, especially downstream of the UFZ. The model reproduces observed partial pressure of carbon dioxide in the surface water (pCO2) remarkably well from seasonal to interannual timescales relative to prior studies (r = 0.89). The seasonality of pCO2 is difficult to simulate correctly because it is a small residual between the opposing influences of temperature and carbon. This model represents an intermittent double peak pattern of pCO2; one driven by the summertime high temperature and another from the wintertime high of dissolved inorganic carbon. The model also captures the spatial and temporal structure of the regional net primary production with respect to the satellite ocean color products (r = 0.57). The model is further validated by comparing it with biogeochemical float observations from the Southern Ocean Carbon and Climate Observations and Modeling project, revealing the model performance and challenges to accurately represent physical and biogeochemical properties in frontal regions. © 2022 The Authors. Journal of Advances in Modeling Earth Systems published by Wiley Periodicals LLC on behalf of American Geophysical Union.