[ACG47-12] Regional estimates of CO2 budget using inverse modelling for the past two decades (1996-2018)
Keywords:Atmospheric inversion, CO2 fluxes, regional scale
Monthly CO2 fluxes are estimated using a Time-Dependent Inverse (TDI) model, measurements from 30 sites across the globe and MIROC4-ACTM forward model for the period of 1996-2018. The inversion fluxes are evaluated in details using the independent CO2 measurements made onboard aircraft over 74 sites across the globe. The simulations of CO2 concentrations using inverted fluxes agree within 0.5 ppm at all the aircraft vertical profile sites. The long-term mean land CO2 fluxes are estimated to the -2.2±0.5, 0.04±0.3 and -0.5±0.2 PgC yr-1 in the most recent decade (2009-2018), respectively, for the northern extratropics (NET: 30-90N), tropics (TR: 30S-30N) and southern extratropics (SET: 30-90S). The ocean CO2 fluxes for the same time period and regions are estimated to be -0.9±0.1, 0.3±0.2 and -1.1±0.1 PgC yr-1, respectively. Considering the fossil fuel emissions and land-oceanic sink, the NET and TR regions act as net sources while SET region acts as a net sink. A large fraction of the interannual variability in global CO2 flux anomaly originates over the tropical land regions, induced by El-Niño southern oscillation. Sensitivity studies using different observational network suggest that the use of JAL/NIES CONTRAIL aircraft data between Japan and Australia helps us to better constrain the interannual variations in CO2 fluxes over the Southeast Asia region.