Comparison of CO2 Measurements with CO2 Distributions from New Forward Model Simulations

COMPARISION OF CO2 MEASUREMENTS WITH CO2 DISTRIBUTIONS
FROM NEW FORWARD MODEL SIMULATIONS

Yuping Liu, Science System And Applications, INC (SSAI), NASA/GSFC
S. R. Kawa, Goddard Space Flight Center, NASA
G. J. Collatz, Goddard Space Flight Center, NASA

As a global CO2 transport model, the Parameterized Chemistry and Transport Model (PCTM) has shown its ability in simulation of spatial and temporal variability of CO2 concentration in a continuing series of experiments. The PCTM model run in this study takes NASA GMAO's new MERRA-2 reanalysis as meteorological forcing, NASA/GSFC CASA-GFED3 bio-terrestrial model, CDIAC monthly fossil fuel emissions, and Takahashi 2009 ocean CO2 flux as inputs. While the basic scenario is very similar to previous PCTM simulations, the new model outputs provide a higher spatial resolution of 0.5x0.625 in latitude and longitude, respectively, as well as updated met forcing. The object of this presentation is to evaluate some of our analysis results for the updated model with airborne, spaceborne and ground-based CO2 measurements. At the bottom line, the PCTM outputs with Merra-2, with higher spatial resolution, are better or similar to previous ones, including Merra, when compared to measurements data. A relatively comprehensive comparison of HIPPO CO2 profiles (2009-2011, 5 missions) with co-sampled model CO2 are conducted, which includes correlation analysis for different seasons and different regions. In most cases PCTM modeling shows good skill in representing the CO2 distribution in 3-D space. Differences are also presented and possible causes are discussed. In addition, we show comparisons of PCTM output with TCCON, ESRL tower data, and latest ACOS Gosat XCO2 data. For most of the CO2 observations, no matter column averaged or at some pressure/height levels near earth surface, PCTM shows quite consistent good agreement with the measurement data. The differences between the simulation and measurements provide insights into the CO2 terrestrial emissions/uptake from different surface types in varied seasons and provide an inter-validation of the observations and fluxes.