Reconstructing the recent carbon cycle from atmospheric CO2, delta C-13 and O-2/N-2 observations

This paper presents an attempt to recover the space-time structure of fluxe s of CO, to the atmosphere over the period 1980-1995 from atmospheric conce ntration and isotopic composition measurements. The technique used is Bayes ian synthesis inversion in which sources are aggregated into large regions and their strengths adjusted to match observed concentrations. The sources are constrained by prior estimates based on a priori knowledge. The input d ata are atmospheric CO, concentration measurements from the NOAA/CMDL netwo rk, (CO2)-C-13 composition and O-2/N-2 ratios measured at Cape Grim, Tasman ia by CSIRO Atmospheric Research. The primary findings are a relatively lar ge long-term mean ocean uptake of CO2, and seasonal fluxes over land with s imilar integrated magnitude, but smaller peak amplitude, compared with thos e derived by Fung and co-workers. Predicted interannual variability is smal ler than reported in previous studies. The largest contributor is the ocean ic tropics where fluxes vary on the time scale of the southern oscillation. There is evidence of longer time-scale variation in land uptake. Increases in ocean uptake and northern land uptake in the early 1990s are consistent with a response to the Mt. Pinatubo eruption.