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| Titel |
Effects of seasonal changes on the oxidation capacity of the city air of Santiago de Chile |
| VerfasserIn |
Y. Elshorbany, J. Kleffmann, R. Kurtenbach, E. Lissi, M. Rubio, G. Villena, E. Gramsch, P. Wiesen |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250020764
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| Zusammenfassung |
| A strong seasonal dependence of the pollutant concentration in the city of Santiago de Chile
has been previously reported in different studies. In this study the effects of seasonal changes
on the oxidation capacity has been analysed during summer and winter. The oxidation
capacity of the highly polluted urban area of Santiago de Chile has been evaluated during a
winter measurement campaign from June 25 - July 07, 2005 and the results were compared
with those previously evaluated during the summer campaign from March 8 – 20, 2005. The
hydroxyl (OH) radical budget was evaluated in both campaigns employing a simple
quasi-photostationary-state model (PSS) constrained with simultaneous measurements of
HONO, HCHO, O3, NO, NO2, j(O1D), j(NO2), 13 alkenes and meteorological parameters.
In addition, a zero dimensional photochemical box model based on the Master Chemical
Mechanism (MCMv3.1) has been used to estimate production rates and total free radical
budgets, including OH, HO2 and RO2. Besides the above parameters, the MCM
model has been constrained by the measured CO and volatile organic compounds
(VOCs) including alkanes and aromatics. The mixing ratios of the trace gasses
were generally higher during the winter than the summer. The evaluated daytime
peak OH radical concentration during winter was ~3 Ã 106 which is about 5 times
lower than that during the summer. However, both PSS and MCM models showed
the same OH radical budget during daytime for both summer and winter which
indicates that the primary OH sources and sinks included in the simple PSS model are
predominant. On a 24-h basis, HONO photolysis was shown to be the most important
primary OH radical source comprising alone more than ~52%, ~66% of the total
initial production rate during summer and winter, respectively followed by alkene
ozonolysis, ~ 24%, 30% and photolysis of HCHO ~ 16Â %, 3% and O3 ~ 5 %, |
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