Observations of total alkyl nitrates within the Sacramento Urban Plume

P. A. Cleary (1) , J. G. Murphy (1) , P. J. Wooldridge (1) , D. A. Day (1) , D. B. Millet (2) , M. Mckay (2) , A. H. Goldstein (2, 3) , R. C. Cohen (1, 3, 4)

1 Department of Chemistry
2 Department of Environmental Science
3 Energy and Environment Technologies Division [LBNL Berkeley]
4 EPS - Department of Earth and Planetary Science [UC Berkeley]

During the summer of 2001, NO₂, total peroxy nitrates (?PNs), total alkyl nitrates (?ANs), HNO₃, volatile organic compounds (VOC), CO₂, O₃, and meteorological variables were measured at Granite Bay, CA. The diurnal variation in ?PNs, ?ANs and HNO₃ were all strongly correlated with sunlight, indicating both that they are photochemically produced and that they have a lifetime of a few hours at this site. The mixing ratios of ?ANs ranged as high as 2 ppbv. Mixing ratios at night averaged 0.4 ppbv. Odd-oxygen (O_x=O₃+NO₂) and ?ANs were strongly correlated reflecting both the common chemical source terms and the similar lifetimes of both species. Several approaches to interpreting the simultaneous variations of O_x and ?ANs are described, and used to derive a best estimate of the ?AN yield from the VOC mixture at this site of 4.2% and an estimate of the range that is consistent with the observations of 3.9?5.8%. A yield of 4.2% implies termination of the HO_x catalytic cycle by ?AN formation once every 24 cycles. Analysis of the HNO₃ observations in combination with the ?AN and O₃ measurements suggests that NO_x terminations limit the HO_x chain length to between 4.7 and 6.3.

Domaines: Océan, Atmosphère

P. A. Cleary, J. G. Murphy, P. J. Wooldridge, D. A. Day, D. B. Millet, et al.. Observations of total alkyl nitrates within the Sacramento Urban Plume. Atmospheric Chemistry and Physics Discussions, 2005, 5 (4), pp.4801-4843. ⟨hal-00301616⟩