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| Titel |
On the diurnal variability of particle properties related to light absorbing carbon in Mexico City |
| VerfasserIn |
D. Baumgardner, G. L. Kok, G. B. Raga |
| 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 ; 7, no. 10 ; Nr. 7, no. 10 (2007-05-14), S.2517-2526 |
| Datensatznummer |
250004984
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| Publikation (Nr.) |
 copernicus.org/acp-7-2517-2007.pdf |
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| Zusammenfassung |
| The mass of light absorbing carbon (LAC) in individual, internally mixed aerosol
particles was measured with the Single Particle Soot Photometer (SP2) in April of
2003 and 2005 and evaluated with respect to concentrations of carbon monoxide
(CO), particle bound polycyclic aromatic hydrocarbons (PPAH) and condensation
nuclei (CN). The LAC and CO have matching diurnal trends that are linked to traffic
patterns and boundary layer growth. The PPAH reaches a maximum at the same
time as CO and LAC but returns rapidly back to nighttime values within three hours
of the peak. The number of particles containing LAC ranges between 10% to 40% of
all particles between 150 nm and 650 nm and the mass is between 5% and 25% of
the total mass in this size range. The average LAC equivalent mass diameter varies
between 160 and 230 nm and the thinnest coating of non-light absorbing material is
observed during periods of maximum LAC mass. The coating varies between 10 nm
and 30 nm during the day, but is a strong function of particle size. The mass
absorption cross sections, σabs, derived from the SP2, are 5.0±0.2 m2g−1 and
4.8±0.2 m2g−1, dependent on the optical model used to describe LAC mixtures. The LAC
contributes up to 50% of the total light extinction in the size range from 100 nm to
400 nm. The estimated emission rate of LAC is 1200 metric tons per year in Mexico
City, based upon the SP2 measurements and correlations between LAC and CO. |
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