Comparison Between Satellite CO2 Retrievals With In-situ Measurements

We have compared AIRS, TES, and GOSAT CO2 data sets with in-situ measurements (NOAA ESRL Surface CO2, Aircraft CO2, and TCCON CO2) and utilized zonal means over land to characterize variability and distribution of CO2. In general, zonal averaged CO2 over land for the three satellite data sets are consistent with the surface and TCCON column CO2 data. Retrievals of CO2 from all three satellites show more CO2 in the northern hemisphere than that in the southern hemisphere. The standard deviation of GOSAT column CO2 at each latitude band is larger than those from AIRS and TES mid-tropospheric CO2. GOSAT column CO2 is lower than the AIRS and surface site CO2 in the northern hemisphere high latitudes. The difference between three satellite CO2 retrievals might be related to the different weighting functions in the three satellites CO2 retrievals. Latitudinal distribution of CO2 seasonal cycle amplitudes will be compared between satellite CO2 and in-situ measurements.