GOBAI-O₂-Flux v1.0: Global Gridded Air-sea Oxygen Flux Inferred from a Machine Learning-based Dissolved Oxygen Product

This dataset provides monthly estimates of open ocean air-sea oxygen (O₂) flux on a 1°×1° global grid spanning 64.5°S to 79.5°N from January 2004 through December 2024. The flux estimates are derived from machine learning-based dissolved oxygen fields (GOBAI-O₂ v2.3, Sharp et al., 2023) combined with three gas exchange parameterization schemes and three wind products. Air-sea O₂ fluxes are computed using dissolved oxygen concentrations from GOBAI-O₂, three bubble-mediated gas exchange parameterizations and three 10-meter wind products (CCMP, ERA-5, and JRA-3Q). This combination generates nine flux model configurations. Flux uncertainties are quantified through a large ensemble approach (9000 members) that propagates errors from dissolved oxygen fields, gas exchange parameterizations, and wind products. The ensemble mean flux and standard deviation (1-σ uncertainty) are provided for each grid cell and month. Two versions of the flux product are included: Adjusted Version (GOBAI-O₂-v2.3-Flux-Adjusted.nc): Annual mean dissolved oxygen concentrations are adjusted to constrain global annual mean fluxes to match values derived from scaling ocean heat uptake (averaging 61 Tmol yr⁻¹ over 2004-2024) and regional annual mean fluxes to match ocean inversion estimates. This version is recommended for most applications requiring accurate annual mean flux magnitudes. Raw Version (GOBAI-O₂-v2.3-Flux-Raw.nc): Fluxes calculated directly from GOBAI-O₂ dissolved oxygen fields without annual mean adjustments. This version also includes intermediate variables used in flux calculations (dissolved oxygen concentration, oxygen saturation, seawater density, and gas transfer velocities for each parameterization scheme), enabling users to explore methodological sensitivities or apply alternative constraints. Positive flux values indicate net O₂ outgassing from ocean to atmosphere; negative values indicate oceanic uptake. File Contents Adjusted Version (GOBAI-O₂-v2.3-Flux-Adjusted.nc) Variable Dimensions Units Description lon (360) °E Longitude lat (145) °N Latitude time (252) days since 2000-01-01 Time fgo2_mean (lon, lat, time) mol m⁻² s⁻¹ Ensemble mean air-sea O₂ flux fgo2_unc (lon, lat, time) mol m⁻² s⁻¹ Flux uncertainty (1-σ ensemble standard deviation) fgo2_member (lon, lat, wind, method, time) mol m⁻² s⁻¹ Flux for each gas exchange method and wind product combination area_ocean (lon, lat) m² Ocean grid cell area ice (lon, lat, time) fraction Sea ice concentration wind (3) - Wind product index (1=CCMP, 2=ERA-5, 3=JRA-3Q) method (3) - Gas exchange method index (1=W97, 2=L13, 3=S09) Raw Version (GOBAI-O₂-v2.3-Flux-Raw.nc) Includes all variables from the adjusted version, plus: Variable Dimensions Units Description oxy (lon, lat, time) μmol kg⁻¹ Mixed-layer dissolved oxygen concentration oxy_sat (lon, lat, time) μmol kg⁻¹ Dissolved oxygen saturation concentration rho (lon, lat, time) kg m⁻³ Seawater density delta_P (lon, lat, time) dimensionless Bubble-induced supersaturation fraction (S09 scheme) kt_W97 (lon, lat, time) m s⁻¹ Total gas transfer velocity (Woolf 1997) ks_L13 (lon, lat, time) m s⁻¹ Diffusive gas transfer velocity (Liang et al. 2013) kc_L13 (lon, lat, time) mol m⁻² s⁻¹ Complete bubble dissolution transfer coefficient (Liang et al. 2013) kp_L13 (lon, lat, time) m s⁻¹ Partial bubble dissolution transfer velocity (Liang et al. 2013) ks_S09 (lon, lat, time) m s⁻¹ Diffusive gas transfer velocity (Stanley et al. 2009) kc_S09 (lon, lat, time) mol m⁻² s⁻¹ Complete bubble dissolution transfer coefficient (Stanley et al. 2009) kp_S09 (lon, lat, time) m s⁻¹ Partial bubble dissolution transfer velocity (Stanley et al. 2009) References Liang, J., Deutsch, C., McWilliams, J. C., Baschek, B., Sullivan, P. P., and Chiba, D.: Parameterizing bubble‐mediated air‐sea gas exchange and its effect on ocean ventilation, Glob. Biogeochem. Cycles, 27, 894–905, https://doi.org/10.1002/gbc.20080, 2013. Sharp, J. D., Fassbender, A. J., Carter, B. R., Johnson, G. C., Schultz, C., and Dunne, J. P.: GOBAI-O2 : temporally and spatially resolved fields of ocean interior dissolved oxygen over nearly 2 decades, Earth Syst. Sci. Data, 15, 4481–4518, https://doi.org/10.5194/essd-15-4481-2023, 2023. Stanley, R. H. R., Jenkins, W. J., Lott III, D. E., and Doney, S. C.: Noble gas constraints on air-sea gas exchange and bubble fluxes, J. Geophys. Res. Oceans, 114, https://doi.org/10.1029/2009JC005396, 2009. Woolf, D. K.: Bubbles and their role in gas exchange, in: The Sea Surface and Global Change, edited by: Liss, P. S. and Duce, R. A., Cambridge University Press, 173–206, https://doi.org/10.1017/CBO9780511525025.007, 1997.