Intercomparison
of the climatological variations of Asian summer monsoon precipitation
simulated by 10 GCMs
I.-S. Kang
1, K. Jin 1, B. Wang 2, K.-M. Lau 3,
J. Shukla 4,
V.
Krishnamurthy 4, S. D. Schubert 5, D. E. Wailser 6,
W. F. Stern 7,
A. Kitoh
8, G. A. Meehl 9 , M. Kanamitsu 10, V. Ya.
Galin 11,
V. Satyan 12,
C.-K. Park13, and Y. Liu
14
1 School of Earth and Environment Sciences, Seoul
National University, Seoul, Korea
2 International Pacific Research Center, University of
Hawaii, Hawaii, U.S.A.
3 Climate and Radiation Branch, NASA/Goddard Space
Flight Center, Greenbelt, Maryland, U.S.A.
4 Center for Ocean–Land–Atmosphere
Studies, Institute of Global Environment and Society, Inc., Calverton, Maryland,
U.S.A.
5 Data Assimilation Office,
NASA/GSFC, Greenbelt, Maryland, U.S.A.
6 Institute
for Terrestrial and Planetary Atmospheres, State University of New York, Stony
Brook, New York, U.S.A.
7 Geophysical Fluid Dynamics
Laboratory/NOAA, Princeton University, Princeton, N.J., U.S.A.
8 Meteorological
Research Institute, Tsukuba, Ibaraki, Japan
9 National
Center for Atmospheric Research, Boulder, Colorado, U.S.A.
10 National
Centers for Environmental Prediction, Camp Springs, Maryland, U.S.A.
11 Institute of Numerical Mathematics
of Russian Academy of Sciences, Moscow, Russia
12 Indian
Institute of Tropical Meteorology, Pune, India
13 Climate Prediction Division,
Korea Meteorological Administration, Seoul, Korea
14 Institute of Atmospheric Physics,
Beijing, People’s Republic of China
Corresponding author
address: In-Sik Kang, School of Earth Environment Sciences, Seoul National
University, Seoul, 151-742, Korea
Email: kang@climate.snu.ac.kr
Tel: 82-2-880-6718, Fax: 82-2-885-7357
Abstract
This
paper assesses the overall performance of state-of-the-art atmospheric GCMs
in simulating the climatological variations of summer monsoon rainfall over the
Asian-Western Pacific region and the systematic errors
that are common to a group of GCMs. The GCM data utilized are
obtained from 10 GCM groups participated in the
CLIVAR/Monsoon GCM Intercomparison Project. The model
composite shows that the overall spatial pattern of summer monsoon rainfall is
similar to the observed, although the western Pacific rainfall is relatively
weak. For the simulated precipitation
over the western Pacific, the models can be classified into two categories. The
first category of models simulates the precipitation more
confined to the equatorial region and weaker
precipitation in the subtropical western Pacific compared to the
observed. The second category of models simulates
large precipitation in the subtropical western Pacific but the region is
shifted to the north by 5-10 degree. None of the models realistically reproduce
the observed Mei-yu rain band in the
region from the East China Sea to the mid Pacific. Most of the models produce a rain
band in the continental side of East Asia.
The climatological
variations of simulated summer rainfall are examined in terms of their
amplitude and their principal EOF modes. All models simulate larger amplitudes
of the climatological seasonal variation of Indian summer monsoon than the
observed, whereas most models simulate smaller amplitudes in the western Pacific.
The 10 model composite produces four
leading EOF modes over the Asian-Western Pacific region, which are remarkably
similar to the observed counterparts. The first and second eigenmodes,
respectively, represent the smoothed seasonal march of broad scale monsoon and
the onsets of the Indian and East Asian summer monsoon. The third and fourth
modes relate to the climatological intraseasonal oscillation (CISO). In
contrast to the model composite, several models fail to reproduce the first
principal mode, and most models do not reproduce the observed modes higher than
the second. The CISO of precipitation is also examined over the Indian monsoon
and the East Asia-western Pacific monsoon regions separately.