Geoscience Reference
In-Depth Information
the albedo over the cloudless ocean and land by up to 10-20% and reduce
the direct solar radiation by 30-40% causing a whitish discoloration of the
blue sky, suggesting the importance of the Asian dust on the atmospheric
radiation balance.
The purpose of this study is to estimate direct radiative forcing of
Asian dust and anthropogenic aerosols in association with an intense
Asian dust event observed in Korea during March 19-23, 2002 using
the National Center for Atmospheric Research (NCAR) column radiation
model (CRM) with the simulated spectral-mass concentration distribu-
tion by the Asian Dust Aerosol Model (ADAM) and the aerosol dynamic
model.
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2. Model Description
The meteorological model used in this study is the nonhydrostatic version
of the fifth-generation mesoscale model of (MM5, Pennsylvania State Uni-
versity/NCAR) defined in the
x
,
y
,and
σ
coordinate system.
13
,
14
The domain of the model is shown in Fig. 1. The domain includes
major dust source regions, namely, the Sand, Loess, Gobi and Mixed soil
regions.
7
,
9
The model has a horizontal resolution of 30 km with 25 vertical
layers.
The ADAM
7
,
9
and the aerosol dynamic model
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with the gas-phase
chemistry of the California Institute of Technology (CIT) model and the
aqueous-phase chemistry of the Regional Acid Deposition Model (RADM)
have been used to calculate the temporal and spatial distributions of the
dust concentration and anthropogenic aerosols in the model domain.
The CRM model of NCAR
15
,
16
is used to estimate aerosol direct radia-
tive forcing at the top of atmosphere (TOA) and the surface. This model
uses a
δ
-Eddington approximation with 18 spectral intervals (7 for O
3
,1for
the visible, 7 for H
2
Oand3forCO
2
) spanning the solar spectrum from
0.12 to 5.0
µ
m.
Average mineral components of soils obtained from 37 soil samples in
the Asian dust source regions of the Sand, Gobi, Loess and Mixed Soil in
northern China
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that consist of quartz (49%), plagioclase (22%), k-feldspar
(17%), illite (5%), kaolinite (2%), calcite (2%), gypsum (1%), amphibole
(1%) and 14Ac (1%) are used with the refractive indices of these mineral
components.
12
The emission data of SO
2
,NO
X
,NH
3
, CO, nonmethane volatile organic
carbon (NMVOC), BC, and OC in the model domain are obtained from
