UC Irvine

 Inverse estimation of carbon dioxide (CO₂) sources and sinks uses atmospheric CO₂ observations, mostly made near the Earth's surface. However, transport models used in such studies lack perfect representation of atmospheric dynamics and thus often fail to produce unbiased forward simulations. The error is generally larger for observations over the land than those over the remote/marine locations. The range of this error is estimated by using multiple transport models (16 are used here). We have estimated the remaining differences in CO₂ fluxes due to the use of ocean-only versus all-sites (i.e., over ocean and land) observations of CO₂ in a time-independent inverse modeling framework. The fluxes estimated using the ocean-only networks are more robust compared to those obtained using all-sites networks. This makes the global, hemispheric, and regional flux determination less dependent on the selection of transport model and observation network.