[Park2013] "Active atmosphere-ecosystem exchange of the vast majority of detected volatile organic compounds.",
, vol. 341, no. 6146: Department of Environmental Science, Policy, and Management, University of California at Berkeley, Berkeley, CA 94720, USA., pp. 643–647, Aug, 2013.
<p>Numerous volatile organic compounds (VOCs) exist in Earth's atmosphere, most of which originate from biogenic emissions. Despite VOCs' critical role in tropospheric chemistry, studies for evaluating their atmosphere-ecosystem exchange (emission and deposition) have been limited to a few dominant compounds owing to a lack of appropriate measurement techniques. Using a high-mass resolution proton transfer reaction-time of flight-mass spectrometer and an absolute value eddy-covariance method, we directly measured 186 organic ions with net deposition, and 494 that have bidirectional flux. This observation of active atmosphere-ecosystem exchange of the vast majority of detected VOCs poses a challenge to current emission, air quality, and global climate models, which do not account for this extremely large range of compounds. This observation also provides new insight for understanding the atmospheric VOC budget.</p>
 "Airborne Flux Measurements of BVOCs above Californian Oak Forests: Experimental Investigation of Surface and Entrainment Fluxes, OH Densities, and Damköhler Numbers",
J. Atmos. Sci.
, vol. 70, pp. 3277–3287, Oct, 2013.
Link: http://nature.berkeley.edu/ahg/pubs/Karl et al 2013 JAS.pdf
<p>Airborne flux measurements of isoprene were performed over the Californian oak belts surrounding the Central Valley. The authors demonstrate for the first time 1) the feasibility of airborne eddy covariance measurements of reactive biogenic volatile organic compounds; 2) the effect of chemistry on the vertical transport of reactive species, such as isoprene; and 3) the applicability of wavelet analysis to estimate regional fluxes of biogenic volatile organic compounds. These flux measurements demonstrate that instrumentation operating at slower response times (e.g., 1–5 s) can still be used to determine eddy covariance fluxes in the mixed layer above land, where typical length scales of 0.5–3 km were observed. Flux divergence of isoprene measured in the planetary boundary layer (PBL) is indicative of OH densities in the range of 4–7 × 106 molecules per cubic centimeter and allows extrapolation of airborne fluxes to the surface with Damköhler numbers (ratio between the mixing time scale and the chemical time scale) in the range of 0.3–0.9. Most of the isoprene is oxidized in the PBL with entrainment fluxes of about 10% compared to the corresponding surface fluxes. Entrainment velocities of 1–10 cm s−1 were measured. The authors present implications for parameterizing PBL schemes of reactive species in regional and global models.</p>