New Constraints On The Mechanism Of Isoprene Oxidation By OH: Laboratory And Field Observations For DC3, SOAS, And SEAC4RS

Wednesday, 17 December 2014: 8:15 AM
Paul O Wennberg, John Crounse, Jason Michael St Clair, Tran Nguyen and Alex Teng, California Institute of Technology, Pasadena, CA, United States
Measurements of the oxidation products of isoprene in both the laboratory and in the field provide a wealth of new information on the mechanism of isoprene degradation. In particular measurements of hydroperoxides and nitrates provide a key constraints on the flow of carbon via NO, HO2, and unimolecular chemistry.

In the field, we observe transitions from NO-dominated chemistry to oxidation dominated by HO2 and isomerization due to spatial and temporal variability in NOx. This transition maps onto the rate of oxidant production and consumption. We show that the Southeastern US is now undergoing a rapid transition from the former to the latter. Implications for ozone and aerosol formation will be described.