Tracer-based Estimates of Transport Uncertainty from NASA's GEOS-5 AGCM: Implications for Inversion Flux Estimates (Invited Presentation)

Uncertainty in atmospheric transport has long been recognized as a major source of uncertainty in carbon fluxes estimated by inversion studies. Observations of the column-averaged dry air mixing ratio of CO2 (XCO2) from satellites have the potential to improve carbon flux estimates, but quantification of transport errors is needed to fully realize the potential of these datasets. Ongoing work using NASA's Goddard Earth Observing System Model, Version 5 (GEOS-5) has focused on quantifying meteorological transport uncertainty and its impact on atmospheric CO2 mixing ratios using ensemble methods in conjunction with tagged error tracers. Tracers with different prescribed lifetimes are used to provide insight into the persistence and spatio-temporal propagation of transport errors. We will present results of comparisons between GEOS-5 simulated CO2 and in situ and satellite observations of CO2 and discuss the estimates of transport uncertainty associated with different types of model-data comparisons. The implications for inversion modeling studies will also be discussed.