Optimal determination of the parameters controlling biospheric CO2 fluxes over Europe using eddy covariance fluxes and satellite NDVI measurements

Ecosystem CO2 flux measurements using the eddy covariance method were compared with the biospheric CO2 exchange estimates of a regional scale atmospheric model. The model described the seasonal patterns quite well, but underestimated the amplitude of the fluxes, especially at the northern sites. Two model parameters, photosynthetic efficiency for light use and Q(10) for soil respiration, were re-evaluated on a diurnal and seasonal basis using the results from flux measurements. In most cases the photosynthetic efficiency was higher than the earlier estimate. The resulting flux was very sensitive to the value of photosynthetic efficiency, while changes in Q(10) to did not have a significant effect.