Satellite ocean color assessment of air‐sea fluxes of CO₂ in a river‐dominated coastal margin

Quantification of the contributions of river‐influenced margins to regional CO 2 fluxes is difficult due to the high degree of spatial and temporal variability in these regions. We describe an algorithm for assessment of surface water partial pressure of CO 2 ( p CO 2 ) from MODIS imagery in the northern Gulf of Mexico. Principal component analysis and multiple regression were used to relate surface p CO 2 to environmental variables (T, S, chlorophyll). Subsequent retrieval of corresponding products from MODIS‐Aqua L1B data permitted the assessment of regional distributions of p CO 2 . An area of low p CO 2 was evident in the vicinity of the Mississippi River delta, consistent with field observations. Regional surface air to sea fluxes of CO 2 were estimated as 2.0–4.2 mmol C m −2 d −1 .