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| Titel |
Spring and summer contrast in new particle formation over nine forest areas in North America |
| VerfasserIn |
F. Yu, G. Luo, S. C. Pryor, P. R. Pillai, S. H. Lee, J. Ortega, J. J. Schwab, A. G. Hallar, W. R. Leaitch, V. P. Aneja, J. N. Smith, J. T. Walker, O. Hogrefe, K. L. Demerjian |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 24 ; Nr. 15, no. 24 (2015-12-18), S.13993-14003 |
| Datensatznummer |
250120235
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| Publikation (Nr.) |
 copernicus.org/acp-15-13993-2015.pdf |
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| Zusammenfassung |
| Recent laboratory chamber studies indicate a significant role for
highly oxidized low-volatility organics in new particle formation (NPF), but
the actual role of these highly oxidized low-volatility organics in
atmospheric NPF remains uncertain. Here, particle size distributions (PSDs)
measured in nine forest areas in North America are used to characterize the
occurrence and intensity of NPF and to evaluate model simulations using an
empirical formulation in which formation rate is a function of the
concentrations of sulfuric acid and low-volatility organics from
alpha-pinene oxidation (Nucl-Org), and using an ion-mediated nucleation
mechanism (excluding organics) (Nucl-IMN). On average, NPF occurred on
~ 70 % of days during March for the four forest sites with
springtime PSD measurements, while NPF occurred on only ~ 10 % of days in July for all nine forest sites. Both Nucl-Org and Nucl-IMN
schemes capture the observed high frequency of NPF in spring, but the
Nucl-Org scheme significantly overpredicts while the Nucl-IMN scheme
slightly underpredicts NPF and particle number concentrations in summer.
Statistical analyses of observed and simulated ultrafine particle number
concentrations and frequency of NPF events indicate that the scheme without
organics agrees better overall with observations. The two schemes predict
quite different nucleation rates (including their spatial patterns),
concentrations of cloud condensation nuclei, and aerosol first indirect
radiative forcing in North America, highlighting the need to reduce NPF
uncertainties in regional and global earth system models. |
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