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| Titel |
A study on the aerosol optical properties over East Asia using a combination of CMAQ-simulated aerosol optical properties and remote-sensing data via a data assimilation technique |
| VerfasserIn |
R. S. Park, C. H. Song, K. M. Han, M. E. Park, S.-S. Lee, S.-B. Kim, A. Shimizu |
| 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 ; 11, no. 23 ; Nr. 11, no. 23 (2011-12-08), S.12275-12296 |
| Datensatznummer |
250010250
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| Publikation (Nr.) |
 copernicus.org/acp-11-12275-2011.pdf |
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| Zusammenfassung |
| To more accurately estimate direct radiative forcing
(DRF) by aerosols, and better investigate particulate pollution over East
Asia, precise calculations of the optical properties of aerosols, such as
aerosol optical depth (AOD), single scattering albedo (SSA) and aerosol
extinction coefficient (σext), are of primary importance. The
aerosol optical properties over East Asia were investigated in this study,
based on US EPA Models-3/CMAQ v4.5.1 model simulations. The CMAQ model
simulations in this study were improved in several ways compared to those in
a previous study (Song et al., 2008). Although the details of the
improvements were described in the manuscript, the following points should
be emphasized: (1) two data assimilation techniques were employed for
producing more accurate AOD products and meteorological fields over East
Asia; (2) updated/upgraded emission inventories were used in the CMAQ model
simulations with a fine grid resolution of 30 × 30 km2; and (3)
the 4-D particulate composition calculated from the CMAQ model simulations
was converted into 3-D or 4-D aerosol optical products, using the Malm and
Hand (2007) algorithm with significant further modifications. The results
from the CMAQ model simulations (without assimilation) showed great
improvements compared to those from a previous study. For example, in terms
of the regression coefficients (R), R values were increased from 0.48–0.68
(previous study) to 0.62–0.79 (this study). The monthly-averaged
CMAQ-simulated single scattering albedo (SSA) also agreed well with the
AERONET SSA, with the exceptions of the Hong Kong and Taipei sites, where
the air qualities were strongly influenced by active biomass burning events
from January to April. There were also excellent matches between the
vertical profiles of the CMAQ-simulated σext and
LIDAR-retrieved σext. It was also found that the contributions
of (NH4)2SO4 during summer, NH4NO3 during winter,
sea-salt particles during winter and dust particles during spring to the
total AOD were large over East Asia. In particular, the largest contribution
of NH4NO3 to the total AOD was found over East Asia during winter.
Therefore, it was suggested that this contribution of NH4NO3
should not be neglected. In order to produce more accurate AOD products, the
CMAQ-simulated AODs were further assimilated with the MODIS-retrieved AODs.
Both of the assimilated and AERONET AODs were better correlated with each
other than the CMAQ-simulated and AERONET AODs. The obvious benefits from
this study would be that with these improved aerosol optical properties, the
particulate pollution (e.g. AOD can be served as a proxy to PM2.5 or
PM10) and DRF by aerosols over East Asia can be more satisfactorily
investigated in future. |
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