Fluxes and concentrations of BVOCs from CABERNET aircraft campaign over California

Aircraft-scale fluxes of Biogenic Volatile Organic Compounds (BVOC) were measured over California by direct eddy covariance (vDEC approach) using PTR-MS onboard a CIRPAS Twin Otter aircraft during June 2011. The CABERNET (California Airborne BVOC Emission Research in Natural Ecosystem Transects) project was focused on areas of California where BVOC emissions are expected to be high based on model estimates in order to improve the accuracy of modeled predictions for these important ozone and aerosol precursor compounds. The campaign succeeded in measuring emissions with the largest coverage with respect to biogenic sources, so far conducted, of isoprene, MVK+MAC, methanol, monoterpenes, and MBO. In addition, acetaldehyde was measured from rice fields in the delta region. BVOC fluxes were measured over a variety of ecosystems, but the major isoprene emissions observed were from oak woodlands. Isoprene emissions from agricultural crop regions and shrublands were generally low. According to MEGAN and BEIGIS models, commonly used in California to predict emissions of BVOC, oak woodlands are dominant contributors of isoprene to the atmosphere. Therefore, isoprene emissions from California oak lands are important for atmospheric photochemistry, particularly at the interface with polluted air from Central Valley regions, whose advected air masses exceeded 80 ppbv of ozone on a sunny day.