Seasonal and inter-annual variability of atmosphere CO2 based on NOAA Carbon Tracker analysis and satellite observations.

A study on seasonal and inter-annual variability of the atmospheric CO₂ is carried out based on National Oceanic and Atmospheric Administration Carbon Tracker (NOAACT) re-analysis and satellite measurements of midtroposphere CO₂ by Atmosphere Infrared Sounder on board NASA's Aqua and lower troposphere CO₂ by Greenhouse-gas Observing Satellite. Seasonal and nonseasonal components of each time series were extracted by means of least square based harmonic analysis procedure. The data of surface CO₂ fluxes used in the NOAACT are also analyzed to examine its relationship with the atmosphere CO₂ variability at different time scales. There exists good consistency between NOAACT analysis and satellite observations in their respective seasonal harmonics and climatology. Surface layer CO₂ exhibits large climatological mean over the regions of major anthropogenic sources together with strong seasonal cycle over the humid and cold climatic terrestrial regions especially over the northern hemisphere. Existence of high coherency with the different components of the surface fluxes shows that surface layer atmosphere CO₂ seasonality is primarily contributed from the terrestrial ecosystem exchanges and secondarily by anthropogenic and oceanic exchanges. The mid-troposphere CO₂ exhibits large values associated with climatology and amplitudes of semi-annual and annual cycles over the northern extra tropics and Polar Regions along with a gradual decreasing trend from northern to southern hemisphere. Inter-annual variability of atmospheric CO₂ in the NOAACT in some extent is consistent with the satellite observations. Large scale circulation patterns, its fluctuations associated with ENSO events and large scale ecosystem disturbances have significant influence on the inter-annual variability. [ABSTRACT FROM AUTHOR]