Comment on egusphere-2025-5196

Abstract. Current estimates of the global ocean carbon sink based on measurements of CO2 fugacity are inconsistent with those obtained from global ocean biogeochemistry models. Here we investigate how this gap might be partially closed by more fully accounting for submonthly variability in observation-based estimates. While these data-estimates compute the air-sea CO2 flux based on hourly wind speed, other variables have only monthly resolution. Thus, they neglect high-frequency variability from short-term synoptic events such as storms for key variables such as atmospheric pressure. To evaluate this error, we compare data-based flux estimates from observational data sets having different temporal resolutions. We find that accounting for hourly variations in atmospheric pressure and daily variations in sea surface temperature in a data-based approach reduces the resulting estimate of global carbon uptake by 0.12 Pg C yr−1, closing 25 % of the average gap between observation-based and model estimates. The cause is proper accounting of the covariance between wind speed and atmospheric pressure, particularly in the southern extratropics.