CERES, the CarboEurope Regional Experiment Strategy in Les Landes, South West France, May-June 2005

Quantification of sources and sinks at global and regional scales requires not only a good description of the land sources and sinks of carbon, but also of the synoptic and mesoscale meteorology. An experiment was performed in les Landes, South West France, to determine the variability in concentration gradients and fluxes of CO2 . Several aircraft sampled the CO2 concentration and fluxes over the area, while fixed stations observed the fluxes and concentrations at high precision. Several (mesoscale) meteorological modeling tools were used to plan the experiment and flight patterns. Results show that at regional scale the relation between profiles and fluxes is not obvious, and strongly influenced by airmass history and mesoscale flow patterns. This calls for an experimental and modeling strategy that takes into account the large spatial gradients in concentrations and the variability in sources and sinks that arise from different land use types. We briefly describe such an analysis.