Geoscience Reference
In-Depth Information
DIRECT RADIATIVE FORCING DUE
TO ANTHROPOGENIC AEROSOL AND ASIAN
DUST IN MARCH 2002 OVER EAST ASIA
SOON-UNG PARK
∗
and EUN-HEE LEE
School of Earth and Environmental Sciences
Seoul National University, Seoul, 151-742, Korea
∗
supark@snu.ac.kr
The Asian Dust Aerosol Model (ADAM) and the aerosol dynamic model with
the output of the fifth generation of mesoscale model (MM5) in a grid of 30
×
30 km
2
have been employed to simulate the temporal and spatial distribution
of the Asian dust aerosol and the anthropogenic aerosol concentrations in East
Asia for the period of March 19-23, 2002 when a severe Asian dust event
(Hwangsa) was observed in Korea. The simulated aerosols are used to estimate
radiative forcing at the surface and the top of the atmosphere (TOA) with
the use of the National Center for Atmospheric Research (NCAR) column
radiation model (CRM) from the community climate model 3 (CCM3). The
results indicate that the estimated mean total aerosol mass in the analysis
domain for the period of March 19-20, 2002 is found to be about 880 mg/m
2
,of
which 98 and 2% are, contribute to the Asian dust aerosol and anthropogenic
aerosol, respectively. However, the direct radiative forcing contribution from
the anthropogenic aerosols is found to be about 40% of the mean radiative
forcing at the surface (
−
11 W
/
m
2
) and 45% at TOA (
−
6W
/
m
2
), implying
the importance of the anthropogenic aerosol component on the direct radiative
forcing at both the surface and TOA.
1. Introduction
Wind-blown mineral dust from deserts and semi-arid regions are impor-
tant sources of tropospheric aerosols
1
and play an important role in the
earth-atmosphere radiative system. It is estimated to contribute 1000 to
3000 Tg/year
1
to global atmospheric emissions of aerosols.
2
-
4
Dust storms have become a distinct feature in many regions around
the globe, including East Asia, West Africa, and South America.
5
,
6
In East
Asia, Asian dust (Hwangsa in Korean) which is a typical example of mineral
aerosol frequently occurs in the Sand desert, Gobi desert and Loess plateau
in northern China and Mongolia during the spring season.
7
-
9
Some of the
Asian dust is reported to reach western parts of the USA across the Pacific
Ocean.
10
,
11
Husar
et al.
10
indicate that the dust clouds in East Asia increase
55
