ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-5-67-2005 Observations of oxidation products above a forest imply biogenic emissions of very reactive compounds Holzinger R. 1 Lee A. 1 Paw K. T. 2 Goldstein U. A. H. 1 Department of Environmental Science, Policy, and Management (ESPM), Division of Ecosystem Sciences, University of California, Berkeley, California, 94720-3110, USA Atmospheric Science Program, Department of Land, Air, and Water Resources, University of California, Davis, California, 95616-8717, USA 20 01 2005 5 1 67 75 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/5/67/2005/acp-5-67-2005.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/5/67/2005/acp-5-67-2005.pdf

Vertical gradients of mixing ratios of volatile organic compounds have been measured in a Ponderosa pine forest in Central California (38.90&deg; N, 120.63&deg; W, 1315m). These measurements reveal large quantities of previously unreported oxidation products of short lived biogenic precursors. The emission of biogenic precursors must be in the range of 13-66&micro;mol m<sup>-2</sup>h<sup>-1</sup> to produce the observed oxidation products. That is 6-30 times the emissions of total monoterpenes observed above the forest canopy on a molar basis. These reactive precursors constitute a large fraction of biogenic emissions at this site, and are not included in current emission inventories. When oxidized by ozone they should efficiently produce secondary aerosol and hydroxyl radicals.