Global CO₂ transport simulations using meteorological data from the NASA data assimilation system

We present a first analysis of atmospheric CO 2 transport using meteorological data from the NASA finite volume data assimilation system (FVDAS). The analyzed meteorological fields are used along with climatological surface sources and sinks in an off‐line, forward transport simulation for 1998–2000. Analysis of model diagnostics and comparisons to previous results indicates that the model performance is consistent with that of most previous global transport models. The model interhemispheric gradients along with the timing and magnitude of the CO 2 seasonal cycle are discussed, providing inferences regarding the northern biosphere, tropical land, and southern ocean fluxes. Global distributions of column‐integrated CO 2 are presented to provide a basis for measurement requirements for the design of satellite‐based instruments for atmospheric CO 2 column. On the synoptic scale we find a significant benefit in using the FVDAS analyzed winds for comparisons to data. At near‐equatorial observation sites, the model correctly simulates the observed atmospheric composition transition associated with the latitudinal movement of the ITCZ. Comparison to daily data from continuous analyzer sites shows the model captures a substantial amount of the observed synoptic variability due to transport changes. These results show the potential to use high temporal and spatial resolution remote sensing data to constrain CO 2 surface fluxes, and they form the starting point for developing an operational CO 2 assimilation system to produce high‐resolution distributions of atmospheric CO 2 and quantitative estimates of the global carbon budget.