Observations of Products formed from the Interactions of Biogenic and Anthropogenic Emissions over a Ponderosa Pine Forest

Photooxidation products of isoprene and 2-methyl-3-buten-2-ol known to form under low and high NOx conditions have been observed at a forest site on the Western edge of the Sierra Nevada during the BEARPEX 2009 campaign, using chemical ionization mass spectrometry. Globally, biogenic volatile organic compounds, BVOCs, emissions are a large contribution of reduced carbon to the atmosphere. The products from the photooxidation of these BVOCs are highly dependent on the presence and concentration of nitrogen oxides (NOx) in the atmosphere. This site experiences an afternoon influx of anthropogenically influenced air from the Central California Valley, providing two chemical regimes to investigate the biogenic oxidation chemistry. Diurnal profiles and time series of these oxidation products from the summer of 2009 will be presented.