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Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 13, 4359-4377, 2016
https://doi.org/10.5194/bg-13-4359-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
08 Aug 2016
Modeling pCO2 variability in the Gulf of Mexico
Zuo Xue1,2,3, Ruoying He4, Katja Fennel5, Wei-Jun Cai6, Steven Lohrenz7, Wei-Jen Huang8, Hanqin Tian9, Wei Ren10, and Zhengchen Zang1 1Department of Oceanography and Coastal Sciences, Louisiana State University, Baton Rouge, LA, USA
2Center for Computation and Technology, Louisiana State University, Baton Rouge, LA, USA
3Coastal Studies Institute, Louisiana State University, Baton Rouge, LA, USA
4Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, NC, USA
5Department of Oceanography, Dalhousie University, Halifax, Canada
6School of Marine Science and Policy, University of Delaware, Newark, DE, USA
7School for Marine Science and Technology, University of Massachusetts Dartmouth, New Bedford, MA, USA
8Department of Oceanography, National Sun Yat-sen University, Kaohsiung, Taiwan
9School of Forestry and Wildlife Sciences, Auburn University, AL, USA
10Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY, USA
Abstract. A three-dimensional coupled physical–biogeochemical model was used to simulate and examine temporal and spatial variability of sea surface pCO2 in the Gulf of Mexico (GoM). The model was driven by realistic atmospheric forcing, open boundary conditions from a data-assimilative global ocean circulation model, and observed freshwater and terrestrial nutrient and carbon input from major rivers. A 7-year model hindcast (2004–2010) was performed and validated against ship measurements. Model results revealed clear seasonality in surface pCO2 and were used to estimate carbon budgets in the Gulf. Based on the average of model simulations, the GoM was a net CO2 sink with a flux of 1.11 ± 0.84  ×  1012 mol C yr−1, which, together with the enormous fluvial inorganic carbon input, was comparable to the inorganic carbon export through the Loop Current. Two model sensitivity experiments were performed: one without biological sources and sinks and the other using river input from the 1904–1910 period as simulated by the Dynamic Land Ecosystem Model (DLEM). It was found that biological uptake was the primary driver making GoM an overall CO2 sink and that the carbon flux in the northern GoM was very susceptible to changes in river forcing. Large uncertainties in model simulations warrant further process-based investigations.

Citation: Xue, Z., He, R., Fennel, K., Cai, W.-J., Lohrenz, S., Huang, W.-J., Tian, H., Ren, W., and Zang, Z.: Modeling pCO2 variability in the Gulf of Mexico, Biogeosciences, 13, 4359-4377, https://doi.org/10.5194/bg-13-4359-2016, 2016.
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In this study we used a state-of-the-science coupled physical–biogeochemical model to simulate and examine temporal and spatial variability of sea surface CO2 concentration in the Gulf of Mexico. Our model revealed the Gulf was a net CO2 sink with a flux of 1.11 ± 0.84 × 1012 mol C yr−1. We also found that biological uptake was the primary driver making the Gulf an overall CO2 sink and that the carbon flux in the northern Gulf was very susceptible to changes in river inputs.
In this study we used a state-of-the-science coupled physical–biogeochemical model to simulate...
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