Air-sea CO₂ fluxes on the US Middle Atlantic Bight

One objective of the Ocean Margins Program (OMP) was to quantify air-sea CO₂ fluxes on the US Middle Atlantic Bight (MAB). No measurements of the partial pressure of CO₂ (pCO₂) had been reported for the MAB prior to the 1994 OMP field program. A number of field studies have now taken place that include ship and mooring-based measurements of pCO₂ spanning the years 1994-2000. We use these data to quantify the annual air-sea CO₂ flux on the MAB. These calculations indicate that the MAB is a net annual sink for atmospheric CO₂, with the inner, mid, and outer-shelf regions taking up ̃0.1, 0.7, and 0.2 Mt C yr^-1, respectively, for a net uptake of ̃1±0.6 Mt C yr^-1. The annual cycle of heating and cooling combined with high winds during the period of undersaturation (winter) appear to account for a significant portion of the uptake. The flux uncertainty is dominated by uncertainty of the gas-transfer velocity parameterization, atmospheric CO₂ levels, and coarse spatial pCO₂ resolution. Errors due to monthly averaging of wind and pCO₂ time-series ate relatively small in comparison. Recent results from other ocean margin regions found a significantly larger flux (in mol m^-2 yr^-1). Unlike the MAB, the increase in pCO₂ due to summer heating appears to be counterbalanced by new production and the pCO₂ never rises significantly above atmospheric saturation in these areas.