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Biogeosciences An interactive open-access journal of the European Geosciences Union
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https://doi.org/10.5194/bg-2019-430
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-2019-430
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 07 Nov 2019

Submitted as: research article | 07 Nov 2019

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Biogeosciences (BG).

Seasonal patterns of surface inorganic carbon system variables in the Gulf of Mexico inferred from a regional high-resolution ocean-biogeochemical model

Fabian A. Gomez1,2, Rik Wanninkhof2, Leticia Barbero3,2, Sang-Ki Lee2, and Frank J. Hernandez Jr.4 Fabian A. Gomez et al.
  • 1Escuela de Ciencias del Mar, Pontificia Universidad Catolica de Valparaiso, Avenida Altamirano 1480, Valparaiso, Chile
  • 2NOAA Atlantic Oceanographic and Meteorological Laboratory, 4301 Rickenbacker Causeway, Miami, FL 33149, USA
  • 3Cooperative Institute for Marine and Atmospheric Studies, University of Miami, 4600 Rickenbacker Causeway, Miami, FL, 33149, USA
  • 4Division of Coastal Sciences, University of Southern Mississippi, 703 East Beach Drive, Ocean Springs, MS, 39564, USA

Abstract. Uncertainties in carbon chemistry variability still remain large in the Gulf of Mexico (GoM), as data gaps limit our ability to infer basin-wide patterns. Here we configure and validate a regional high-resolution ocean-biogeochemical model for the GoM to describe seasonal patterns in surface pressure of CO2 (pCO2), aragonite saturation state (ΩAr), and air-sea CO2 flux during 2005–2014. Model results indicate that seasonal changes in surface pCO2 are strongly controlled by temperature across most of the GoM basin, except in the vicinity of the Mississippi-Atchafalaya River System delta, where runoff largely controls dissolved inorganic carbon (DIC) and total alkalinity (TA) changes. Our model results also show that seasonal patterns of surface ΩAr are driven by seasonal changes in DIC and TA, and reinforced by the seasonal changes in temperature. Simulated air-sea CO2 fluxes are consistent with previous observation-based estimates that show CO2 uptake during winter-spring, and CO2 outgassing during summer-fall. Annually, our model indicates a basin-wide mean CO2 uptake of 0.35 mol m−2 yr−1, and a northern GoM shelf (< 200 m) uptake of 0.93 mol m−2 yr−1. The observation and model-derived patterns of surface pCO2 and CO2 fluxes show good correspondence, thus contributing to improved constraints of the carbon budget in the region.

Fabian A. Gomez et al.
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Fabian A. Gomez et al.
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Short summary
We use a numerical model to infer annual changes of surface carbon chemistry in the Gulf of Mexico (GoM). The main seasonality drivers of partial pressure of carbon dioxide and aragonite saturation state from the model are temperature and river runoff. The GoM basin is a carbon sink in winter-spring and carbon source in summer-fall, but uptake prevails near the Mississippi delta year-round due to high biological production. Our model results show good correspondence with observational studies.
We use a numerical model to infer annual changes of surface carbon chemistry in the Gulf of...
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