Development of a spatially explicit inventory of methane emissions from Australia and its verification using atmospheric concentration data

A spatially explicit inventory of CH4 emissions was compiled for Australia to give net CH4 emissions of 85, 391 and 2609 Ggyr−1 from Tasmania, central-south and southeast Australia in 1997, respectively. These estimates were refined by applying the synthesis filtering technique to in situ surface CH4 concentrations measured at Cape Grim, (40.68°S,144.68°E). The refined estimates are 65, 249 and 1502 Ggyr−1, respectively, with uncertainties of the estimates being reduced by 25%, 50% and 80%, respectively. Sensitivity analysis shows that the inversion results do not change significantly under a range of assumptions. The inventory is therefore considered to significantly overestimate net emissions from central-south and southeast Australia in 1997. We also conclude that in situ CH4 concentration measurements can provide definite constraints for estimating regional CH4 emissions in Australia.