Direct N2O5 reactivity measurements at a polluted coastal site

T. P. Riedel, T. H. Bertram, O. S. Ryder, S. Liu, D. A. Day, L. M. Russell, Cassandra Gaston, K. A. Prather, J. A. Thornton

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Abstract

Direct measurements of N2O5 reactivity on ambient aerosol particles were made during September 2009 at the Scripps Institution of Oceanography (SIO) Pier facility located in La Jolla, CA. N2O 5 reactivity measurements were made using a custom flow reactor and the particle modulation technique alongside measurements of aerosol particle size distributions and non-refractory composition. The pseudo-first order rate coefficients derived from the particle modulation technique and the particle surface area concentrations were used to determine the population average N 2O5 reaction probability, γ(N 2O5), approximately every 50 min. Insufficient environmental controls within the instrumentation trailer led us to restrict our analysis primarily to nighttime measurements. Within this subset of data, γ(N2O5) ranged from <0.001 to 0.029 and showed significant day-to-day variations. We compare these data to a recent parameterization that utilizes aerosol composition measurements and an aerosol thermodynamics model. The parameterization captures several aspects of the measurements with similar general trends over the time series. However, the parameterization persistently overestimates the measurements by a factor of 1.5-3 and does not illustrate the same extent of variability. Assuming chloride is internally mixed across the particle population leads to the largest overestimates. Removing this assumption only partially reduces the discrepancies, suggesting that other particle characteristics that can suppressγ (N2O5) are important, such as organic coatings or non-aqueous particles. The largest apparent driver of day-to-day variability in the measured γ (N2O 5) at this site was the particle nitrate loading, as inferred from both the measured particle composition and the parameterizations. The relative change in measured γ(N2O5) as a function of particle nitrate loading appears to be consistent with expectations based on laboratory data, providing direct support for the atmospheric importance of the so-called "nitrate effect".

Original languageEnglish (US)
Pages (from-to)2959-2968
Number of pages10
JournalAtmospheric Chemistry and Physics
Volume12
Issue number6
DOIs
StatePublished - Dec 1 2012
Externally publishedYes

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parameterization
aerosol
nitrate
particle
aerosol composition
pier
oceanography
instrumentation
coating
surface area
thermodynamics
chloride
particle size
time series

ASJC Scopus subject areas

  • Atmospheric Science

Cite this

Riedel, T. P., Bertram, T. H., Ryder, O. S., Liu, S., Day, D. A., Russell, L. M., ... Thornton, J. A. (2012). Direct N2O5 reactivity measurements at a polluted coastal site. Atmospheric Chemistry and Physics, 12(6), 2959-2968. https://doi.org/10.5194/acp-12-2959-2012

Direct N2O5 reactivity measurements at a polluted coastal site. / Riedel, T. P.; Bertram, T. H.; Ryder, O. S.; Liu, S.; Day, D. A.; Russell, L. M.; Gaston, Cassandra; Prather, K. A.; Thornton, J. A.

In: Atmospheric Chemistry and Physics, Vol. 12, No. 6, 01.12.2012, p. 2959-2968.

Research output: Contribution to journalArticle

Riedel, TP, Bertram, TH, Ryder, OS, Liu, S, Day, DA, Russell, LM, Gaston, C, Prather, KA & Thornton, JA 2012, 'Direct N2O5 reactivity measurements at a polluted coastal site', Atmospheric Chemistry and Physics, vol. 12, no. 6, pp. 2959-2968. https://doi.org/10.5194/acp-12-2959-2012
Riedel TP, Bertram TH, Ryder OS, Liu S, Day DA, Russell LM et al. Direct N2O5 reactivity measurements at a polluted coastal site. Atmospheric Chemistry and Physics. 2012 Dec 1;12(6):2959-2968. https://doi.org/10.5194/acp-12-2959-2012
Riedel, T. P. ; Bertram, T. H. ; Ryder, O. S. ; Liu, S. ; Day, D. A. ; Russell, L. M. ; Gaston, Cassandra ; Prather, K. A. ; Thornton, J. A. / Direct N2O5 reactivity measurements at a polluted coastal site. In: Atmospheric Chemistry and Physics. 2012 ; Vol. 12, No. 6. pp. 2959-2968.
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