Special issue  

The objective of CANOPÉE is to understand and quantify the role of intra-canopy processes in the surface–atmosphere exchange of compounds, focusing on biogenic volatile organic compounds (VOCs), and especially isoprene, which is the first biogenic VOC emitted, and ozone. The novelty of our project is based on the combination of new experimental and modeling approaches, and a multi-disciplinary methodology including branch-scale to canopy-scale measurements for the structural, chemical and ecological characteristics of the canopy. A field campaign was carried out in May–June 2012 at the Observatoire de Haute Provence (OHP/O₃HP) in the southern part of France, on a large oak (Quercus pubescens) forest site. Measurements were set to investigate the geographical and vertical tree distribution (lidar on-board ULA); the isoprene emission rate at the branch level (dynamic enclosure chambers); and the atmospheric chemical composition inside and above the canopy together with concentrations diurnal and vertical variability for key compounds such as ozone, nitrogen oxides and a variety of VOCs (GC-MS and PTR-MS) or aerosols. Data and observations collected will be integrated in a one-dimensional model (CACHE) to improve our knowledge on the intra-canopy processes and their representation in modeling tools, and regional studies will be performed with the chemistry-transport model CHIMERE to assess the impact of such forest sites on regional chemistry and possible future evolution.