Global surface-ocean pCO2 and sea–air CO2 flux variability from an observation-driven ocean mixed-layer scheme

TLDR: A temporally and spatially resolved estimate of the global surface-ocean CO2 partial pressure field and the sea-air CO2 flux is presented, obtained by fitting a simple data-driven diagnostic model of ocean mixed-layer biogeochemistry to surface-of-the-atmosphere (CO2) partial pressure data from the SOCAT v15 database.

Abstract: A temporally and spatially resolved estimate of the global surface-ocean CO2 partial pressure field and the sea–air CO2 flux is presented, obtained by fitting a simple data-driven diagnostic model of ocean mixed-layer biogeochemistry to surface-ocean CO2 partial pressure data from the SOCAT v15 database Results include seasonal, interannual, and short-term (daily) variations In most regions, estimated seasonality is well constrained from the data, and compares well to the widely used monthly climatology by Takahashi et al (2009) Comparison to independent data tentatively supports the slightly higher seasonal variations in our estimates in some areas We also fitted the diagnostic model to atmospheric CO2 data The results of this are less robust, but in those areas where atmospheric signals are not strongly influenced by land flux variability, their seasonality is nevertheless consistent with the results based on surface-ocean data From a comparison with an independent seasonal climatology of surface-ocean nutrient concentration, the diagnostic model is shown to capture relevant surface-ocean biogeochemical processes reasonably well Estimated interannual variations will be presented and discussed in a companion paper