Sea-air CO₂ flux estimated from SOCAT surface-ocean CO₂ partial pressure data and atmospheric CO₂ mixing ratio data

Abstract

Abstract. Surface-ocean CO2 partial pressure data have been assimilated into a simple diagnostic model of surface-ocean biogeochemistry to estimate the spatio-temporal CO2 partial pressure field and ultimately the sea-air CO2 fluxes. Results compare well with the widely used monthly climatology by Takahashi et al. (2009) but also contain some short-term and interannual variations. Fitting the same model to atmospheric CO2 data yields less robust but consistent estimates, confirming that using the partial pressure based estimates as ocean prior in atmospheric CO2 inversions may improve land CO2 flux estimates. Estimated seasonality of ocean-internal carbon sources and sinks is discussed in the light of observed nutrient variations.