We examined the spatio-temporal variability of atmospheric CO<sub>2</sub> over India and its surrounding based on Goddard Earth Observation System Chemical (GEOS-Chem) transport model, satellite and in-situ observations. The model was employed at 2x2.5<sup>0</sup> spatial resolution over the globe with 47 vertical layers between pressure levels 1006-0.01 hPa. It is driven by GEOS meteorological fields along with surface boundary fluxes and anthropogenic emissions from different sources. The model run was performed for the period 2006-2013 and the solutions at three hourly intervals were stored for the analysis. In this paper, we are discussing the seasonal and inter-annual characteristics of simulated atmospheric CO<sub>2</sub> highlighting the uncertainties associated with input data sets in the model. There exist good coherences between model and satellite observation. Simulated CO<sub>2</sub> shows strong seasonality near the surface and has showed decrease in its amplitude upward. Amplitudes of the seasonal and annual cycles are stronger over the northern hemisphere, especially over the land regions.