Evaluation of Arctic Ocean surface carbon fluxes from Atmospheric Inverse Analysis

Atmospheric inverse analyses use optimization methods to calculate surface CO2 fluxes using atmospheric transport models in combination with observed gradients in atmospheric CO2 concentration. In our present study we present an inverse estimate of Arctic Ocean air-sea CO2 fluxes using the GEOSChem–LETKF  system; this system has previously been used to derive estimates of regional North Atlantic CO2 fluxes (Chen et al. 2021). Our analysis reports on estimates of Arctic Ocean fluxes  and assesses patterns of spatial and inter-annual variability.  Our results indicate significant spatial variability of air-sea CO2 fluxes in the different regional seas of the Arctic Ocean. The western Arctic Ocean predominantly act as a sink region for atmospheric CO2.  However,  the eastern Arctic Ocean act more as a source of CO2 . We also present results of sensitivity analyses conducted to assess the impact of alternate ocean prior flux specifications.