The CarboEurope Regional Experiment Strategy: Assessment of the regional carbon balance using inverse and direct methods (Invited)

International audience; The CarboEurope Regional Experiment Strategy took place in the South West of France in 2005 and 2007 gathering several intensive observation periods to estimate the regional carbon balance. Eddy covariance fluxes, atmospheric CO2 concentrations, and the solar induced fluorescence were measured from both towers and aircraft. Additional meteorological observations were used to evaluate the performance of mesoscale models to simulate the observed concentrations. Top-down and bottom-up methods were applied and evaluated against direct ecosystem measurements, demonstrating the potential and the reliability of the carbon flux estimates over the region. Mesoscale modeling showed promising results by simulating most of the observed atmospheric variability. Inverse methodology was used to optimize the carbon balance over the area. The aircraft fluxes aggregated over large footprints (few km) showed an overall agreement with the final estimates from the inversion and the eddy flux towers. The photosynthesis activity was also correlated to the sun-induced fluorescence from ground based and aircraft measurements. Potential improvement of the continental carbon balance and recommendations for designing future regional observation networks are discussed.