CABINEX

The CABINEX (Community Atmosphere-Biosphere INteractions Experiments) campaign in 2009 at the PROPHET tower observatory (Pellston, MI) included multi-university field and modeling investigations to address important questions about biosphere-atmosphere interaction (http://aoss-research.engin.umich.edu/prophet/ CABINEX/science.html) including how biogenic volatile organic compound (BVOC) emissions impact HOx radical chemistry in the near-canopy environment. It has long been speculated that unmeasured/unidentified reactive BVOC emissions to HOx chemistry are important in the canopy airspace and in the atmospheric boundary layer. NCAR scientists collaborated with other members of the CABINEX science team to quantify the potential reactivity from BVOC emissions that have not been quantified by conventional analytical techniques. A branch enclosure OH reactivity measurement system was developed using a comparative reactivity method. OH reactivity of four different tree species was characterized and extrapolated to the ecosystem scale. The results shown in Figure 1 indicate that known BVOCs such as isoprene and monoterpenes account for the measured OH reactivity in most cases. This suggests that the PROPHET tower ecosystem (a dominant North American forest type) is dominated instead by unaccounted reactive oxidation products of known BVOCs (e.g. isoprene and monoterpenes). Complementary studies were conducted in NCAR chemistry laboratories to demonstrate the potential importance of these compounds. The detailed discussion can be found in Kim et al. (2011).