First direct observation of the atmospheric CO₂ year-to-year increase from space

M. Buchwitz (1) , O. Schneising (1) , J. P. Burrows (1) , H. Bovensmann (1) , J. Notholt (1)

1 IUP - Institute of Environmental Physics [Bremen]

The reliable prediction of future atmospheric CO₂ concentrations and associated global climate change requires an adequate understanding of the CO₂ sources and sinks. The sparseness of the existing surface measurement network limits current knowledge about the global distribution of CO₂ surface fluxes. The retrieval of the CO₂ total vertical column from satellite observations is predicted to improve this situation. Such an application however requires very high accuracy and precision on the order of 1% (4 ppm) or better. We report on retrievals of the column-averaged CO₂ dry air mole fraction, denoted XCO₂, from the measurements of the SCIAMACHY satellite instrument between 2003 and 2005. We focus on northern hemispheric large scale CO₂ features such as the CO₂ seasonal cycle and show ? for the first time ? that the atmospheric annual increase of CO₂ can be directly observed using satellite measurements of the CO₂ total column. The satellite retrievals are compared with the global assimilation system CarbonTracker and with local surface CO₂ measurements based on weekly flask sampling. We show that the year-to-year CO₂ increase as determined from the satellite data agrees with the reference data within about 1 ppm/year. We also show that the CO₂ seasonal cycle over northern hemispheric low and mid latitudes can be retrieved with a precision of about 2 ppm. The results presented here demonstrate that it is possible using satellite measurements to retrieved information on the atmospheric CO₂ on the level of a few parts per million.

Domaines: Océan, Atmosphère

M. Buchwitz, O. Schneising, J. P. Burrows, H. Bovensmann, J. Notholt. First direct observation of the atmospheric CO₂ year-to-year increase from space. Atmospheric Chemistry and Physics Discussions, 2007, 7 (3), pp.6719-6735. ⟨hal-00302786⟩