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| Titel |
Single particle diversity and mixing state measurements |
| VerfasserIn |
R. M. Healy, N. Riemer, J. C. Wenger, M. Murphy, M. West, L. Poulain, A. Wiedensohler, I. P. O'Connor, E. McGillicuddy, J. R. Sodeau, G. J. Evans |
| 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 ; 14, no. 12 ; Nr. 14, no. 12 (2014-06-25), S.6289-6299 |
| Datensatznummer |
250118833
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| Publikation (Nr.) |
 copernicus.org/acp-14-6289-2014.pdf |
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| Zusammenfassung |
| A newly developed framework for quantifying aerosol particle diversity and
mixing state based on information-theoretic entropy is applied for the first
time to single particle mass spectrometry field data. Single particle mass
fraction estimates for black carbon, organic aerosol, ammonium, nitrate and
sulfate, derived using single particle mass spectrometer, aerosol mass
spectrometer and multi-angle absorption photometer measurements are used to
calculate single particle species diversity (Di). The average single particle species diversity (Dα) is then related to the species
diversity of the bulk population (Dγ) to derive a mixing state
index value (χ) at hourly resolution. The mixing state index is a
single parameter representation of how internally/externally mixed a particle
population is at a given time. The index describes a continuum, with values
of 0 and 100% representing fully external and internal mixing,
respectively. This framework was applied to data collected as part of the
MEGAPOLI winter campaign in Paris, France, 2010. Di values are low
(~ 2) for fresh traffic and wood-burning particles that contain high mass fractions of black carbon and organic aerosol but low mass fractions of
inorganic ions. Conversely, Di values are higher (~ 4) for aged
carbonaceous particles containing similar mass fractions of black carbon,
organic aerosol, ammonium, nitrate and sulfate. Aerosol in Paris is
estimated to be 59% internally mixed in the size range 150–1067 nm,
and mixing state is dependent both upon time of day and air mass origin.
Daytime primary emissions associated with vehicular traffic and wood-burning
result in low χ values, while enhanced condensation of ammonium nitrate
on existing particles at night leads to higher χ values. Advection of
particles from continental Europe containing ammonium, nitrate and sulfate
leads to increases in Dα, Dγ and χ.
The mixing state index represents a useful metric by which to compare and contrast
ambient particle mixing state at other locations globally. |
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