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| Titel |
Implementation of dust emission and chemistry into the Community Multiscale Air Quality modeling system and initial application to an Asian dust storm episode |
| VerfasserIn |
K. Wang, Y. Zhang, A. Nenes, C. Fountoukis |
| 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 ; 12, no. 21 ; Nr. 12, no. 21 (2012-11-06), S.10209-10237 |
| Datensatznummer |
250011562
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| Publikation (Nr.) |
 copernicus.org/acp-12-10209-2012.pdf |
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| Zusammenfassung |
| The US Environmental Protection Agency's (EPA) Community Multiscale Air
Quality (CMAQ) modeling system version 4.7 is further developed to enhance
its capability in simulating the photochemical cycles in the presence of
dust particles. The new model treatments implemented in CMAQ v4.7 in this
work include two online dust emission schemes (i.e., the Zender and Westphal
schemes), nine dust-related heterogeneous reactions, an updated aerosol
inorganic thermodynamic module ISORROPIA II with an explicit treatment of
crustal species, and the interface between ISORROPIA II and the new dust
treatments. The resulting improved CMAQ (referred to as CMAQ-Dust),
offline-coupled with the Weather Research and Forecast model (WRF), is
applied to the April 2001 dust storm episode over the trans-Pacific domain
to examine the impact of new model treatments and understand associated
uncertainties. WRF/CMAQ-Dust produces reasonable spatial distribution of
dust emissions and captures the dust outbreak events, with the total dust
emissions of ~111 and 223 Tg when using the Zender scheme
with an erodible fraction of 0.5 and 1.0, respectively. The model system can
reproduce well observed meteorological and chemical concentrations, with
significant improvements for suspended particulate matter (PM), PM with
aerodynamic diameter of 10 μm, and aerosol optical depth than the
default CMAQ v4.7. The sensitivity studies show that the inclusion of
crustal species reduces the concentration of PM with aerodynamic diameter of
2.5 μm (PM2.5) over polluted areas. The heterogeneous chemistry
occurring on dust particles acts as a sink for some species (e.g., as a
lower limit estimate, reducing O3 by up to 3.8 ppb (~9%) and SO2 by up to 0.3 ppb (~27%)) and as a
source for some others (e.g., increasing fine-mode SO42− by up to
1.1 μg m−3 (~12%) and PM2.5 by up to 1.4 μg m−3
(~3%)) over the domain. The long-range
transport of Asian pollutants can enhance the surface concentrations of
gases by up to 3% and aerosol species by up to 20% in the Western US. |
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