Estimation of spatial apportionment of greenhouse gas emissions for the UK using boundary layer measurements and inverse modelling technique

A technique is described to independently validate the national emission inventories produced using the methodology of the Intergovernmental Panel on Climate Change (IPCC). A boundary layer budget approach is applied to the United Kingdom and an inverse modelling technique is used to derive total and spatial apportionment of emissions for CO, CO2, CH4, N2O, HFC-134a, HCFC-141b, HCFC-142b and HCFC-22. During the summer of 2005 and September 2006 an aircraft circumnavigating the UK was used to collect data upwind and downwind of the UK coast. The concentration measurements were inverted to produce mapped emissions of the UK. The modelled overall CO flux (2900 ± 107 kt yr−1) and spatial apportionment throughout the UK are remarkably consistent with the official UK NAEI (National Atmospheric Emission Inventory) inventory. The CO2 total emissions (620 ± 105 Mt yr−1) and spatial apportionment are also close to the NAEI. However for N2O and CH4, the estimated annual fluxes, 500 ± 370 kt yr−1 and 3500 (range 0–8000 kt yr−1) respectively, are larger than the NAEI albeit with significant uncertainty. Emissions of four halocarbon compounds were also calculated with total emissions of 3.1 ± 0.4 kt yr−1 for HFC-134a, 0.9 ± 0.6 kt yr−1 for HCFC-141b, 0.56 ± 0.2 kt yr−1 for HCFC-142b and 3.8 ± 1.0 kt yr−1 for HCFC-22 consistent with other published data.

Research highlights
► In this study use an independent technique to evaluate the UK national emissions inventories.
► Aircraft measurements of greenhouse gases around the United Kingdom coast and an inverse modelling technique are used to derive total and spatial apportionment of emissions.
► The total and spatial apportionment of CO and CO2 emissions are consistent with the official UK National Atmospheric Emission Inventory.
► The CH4 and N2O estimated annual fluxes are larger than the official UK National Atmospheric Emission Inventory.