JpGU-AGU Joint Meeting 2020

Presentation information

[E] Oral

A (Atmospheric and Hydrospheric Sciences ) » A-CG Complex & General

[A-CG47] Global Carbon Cycle Observation and Analysis

convener:Kazuhito Ichii(Chiba University), Prabir Patra(Research Institute for Global Change, JAMSTEC), Forrest M. Hoffman(Oak Ridge National Laboratory), Makoto Saito(National Institute of Environmental Studies)

[ACG47-12] Regional estimates of CO2 budget using inverse modelling for the past two decades (1996-2018)

*Naveen Chandra1, Prabir Patra1 (1.Japan Agency for Marine Earth Science and Technology)

Keywords:Atmospheric inversion, CO2 fluxes, regional scale

An improved understanding of the magnitude and location of the CO2 sources (mainly from fossil fuel emissions) and sink (mainly from biospheric and oceanic uptake) is essential for the predictions of future climate feedback. Atmospheric inverse modelling is a powerful tool to estimate spatio-temporal variation of fluxes from an optimal fit to atmospheric CO2 measurements.

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.