East Asian winter monsoon: results from eight AMIP models |
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Authors: | Y Zhang K R Sperber J S Boyle M Dix L Ferranti A Kitoh K M Lau K Miyakoda D Randall L Takacs R Wetherald |
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Institution: | (1) Program for Climate Model Diagnosis and Intercomparison, Lawrence Livermore National Laboratory, Livermore, CA 94550, USA, US;(2) Commonwealth Scientific and Industrial Research Organisation, Mordialloc, Victoria 3195, Australia, AU;(3) European Centre for Medium-Range Weather Forecasts, Shinfield Park, Reading RG29AX, United Kingdom, GB;(4) Meteorological Research Institute, 1-1, Nagamine, Tsukuba-shi, Ibaraki-ken, 305, Japan, JP;(5) Goddard Space Flight Center, NASA, Code 913 Greenbelt, MD 20771, USA, US;(6) IMGA-CNR, Via Emilia Est 770, Modena 41100, Italy, IT;(7) Atmospheric Sciences Department, Colorado State University, Fort Collins, Colorado 80523, USA, US;(8) Goddard Laboratory for Atmospheres, Goddard Space Flight Center, Greenbelt, Maryland 20771, USA, US;(9) Geophysical Fluid Dynamical Laboratory/NOAA, Princeton University, Princeton, New Jersey 08540, USA, US |
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Abstract: | This study evaluates simulations of the East Asian winter monsoon in eight GCMs that participated in the Atmospheric Model
Intercomparison Project (AMIP). In addition to validating the mean state of the winter monsoon, the cold surge and its transient
properties, which includes the frequency, intensity, preferred propagation tracks, and the evolution patterns of the surges,
are examined. GCM simulated temporal distribution of the Siberian high and cold surges is also discussed. Finally, the forcing
of the cold surges on the tropical surface wind and convection, along with their interannual variation is analyzed. The mean
state of the winter monsoon is generally portrayed well in most of the models. These include the climatological position of
the Siberian high, the 200 hPa divergent center, and the large-scale wind patterns at the surface and the 200 hPa. Models
display a wide range of skill in simulating the cold surge and its transient properties. In some of the models, the simulated
cold surge trajectory, intensity, frequency, propagation patterns and source regions are in general agreement with those from
the observed. While in others, the models cannot adequately capture these observed characteristics. The temporal distribution
of the Siberian high and cold surges were realistically reproduced in most GCMs. Most models were able to simulate the effect
of the cold surges on the tropical surface wind, although a few models unrealistically generated subtropical southerly wind
in the mid-winter. The relationship between cold surges and the tropical convection was not satisfactorily simulated in most
models. The common discrepancies in the winter monsoon simulation can be attributed to many factors. In some models, the reason
is directly related to the improper location of the large-scale convective center near the western Pacific. The satisfactory
simulations of the monsoon circulation and the cold surges are partly due to the topographical characteristics of the East
Asian continent, i.e., the Tibetan Plateau to the west and the oceans to the east. The correct simulation of the interannual
variation of the surface wind near the South China Sea (SCS) and the maritime continent is a demanding task for most of the
models. This will require adequate simulations of many aspects, including tropical convection, the Siberian cold dome, the
extratropical-tropical linkage, and the air-sea interaction. The discrepancies noted here furnish a guide for the continuing
improvement of the winter monsoon simulations. Improved simulations will lead to an adequate delineation of the surface wind
and convection near the maritime continent, which is essential for portraying the winter monsoon forcing in a coupled model.
Received: 10 March 1997/Accepted: 4 June 1997 |
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