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

[摘要] 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 CO 2 ( p CO 2 ), aragonite saturation state ( Ω Ar ), and sea–air CO 2 flux. Model results indicate that seasonal changes in surface p CO 2 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 Ω Ar are driven by seasonal changes in DIC and TA, and reinforced by the seasonal changes in temperature. Simulated sea–air CO 2 fluxes are consistent with previous observation-based estimates that show CO 2 uptake during winter–spring, and CO 2 outgassing during summer–fall. Annually, our model indicates a basin-wide mean CO 2 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 p CO 2 and CO 2 fluxes show good correspondence; thus this study contributes to improved constraints of the carbon budget in the region.

[学科分类] 大气科学