HR: 11:05h
AN: A52B-03    [Abstracts]
TI: Seasonal variation of biogenic VOCs and oxidation products over a pine forest in California
AU: * Holzinger, R
EM: holzing@nature.berkeley.edu
AF: University of California, Berkeley, ESPM Department -Ecosystem Sciences, 151 Hilgard Hall, Berkeley, CA 94720 United States
AU: Lee, A
EM: alee@nature.berkeley.edu
AF: University of California, Berkeley, ESPM Department -Ecosystem Sciences, 151 Hilgard Hall, Berkeley, CA 94720 United States
AU: McKay, M
EM: megan@nature.berkeley.edu
AF: University of California, Berkeley, ESPM Department -Ecosystem Sciences, 151 Hilgard Hall, Berkeley, CA 94720 United States
AU: Goldstein, A H
EM: ahg@nature.berkeley.edu
AF: University of California, Berkeley, ESPM Department -Ecosystem Sciences, 151 Hilgard Hall, Berkeley, CA 94720 United States
AB: Vertical gradients of volatile organic compounds, using PTR-MS,, and water and CO2, using a LICOR 6262, were measured in a Ponderosa pine forest in the Sierra Nevada, California (38.90§ N, 120.63§ W, 1315m) continuously for 11 months in 2003 and 2004. We have selected two periods representing typical summer (Jun 26 - Sept 23, 2003) and winter (Nov 21, 2003 - Jan 10, 2004) conditions at the site. Median daytime temperatures were 6§C and 26§C in winter and summer, respectively. Vertical fluxes and gradients of water and CO2 revealed significant photosynthetic activity in winter. Concentrations of biogenically emitted 2-methyl-3-buten-2-ol (MBO) and isoprene were a factor of 10-20 lower in winter than in summer. The isoprene oxidation products methyl-vinyl-ketone and methacrolein were 30 times lower showing that their production was slower, consistent with oxidation capacity of the atmosphere being lower in winter. Monoterpene concentrations were only 2-3 times lower in winter. This may reflect either a longer lifetime or a relatively higher emission (compared to MBO or isoprene) of these reactive compounds in winter. The seasonal variation of local emissions, chemistry, and transport will be discussed.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0315 Biosphere/atmosphere interactions
DE: 0365 Troposphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting