Background
Background
Objectives
Methodology
Background
East Asia is located in the southeast part of the Eurasian continent. It is bordered on the east
by the Pacific Ocean and on the southwest by the Tibetan Plateau. The unique geographic
features produce distinct climate characteristics over this region. A workshop was held on
18–20 October 1994 at the State University of New York at Albany to discuss this topic, and the participants agreed to embark a collaborative research project, “General
Circulation Model (GCM) Simulations of the East Asian Climate (EAC)”. The objectives are
to assess the ability of GCMs to simulate EAC, and to study the mechanisms and factors that
cause the multi-scales climate variability. The project was subsequently listed as the
Subproject #25 in the Atmospheric Model Intercomparison Project (AMIP)–Coupled Model
Intercomparison Project (CMIP) with Wei-Chyung Wang as the Coordinator; and
Yihui Ding, Guo-Xiong Wu, Huang-Hsiung Hsu, Akio Kitoh,
and Jeong-Woo Kim as members.
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Participants of the First EAC workshop at Atmospheric Sciences Research Center, State University of New York at Albany: Yong Luo (L3); Wen-Shung Ko (L4); Huang-Hsiung Hsu (L5); Wei-Chyung Wang (L6)；ChongYin Li (R2); Guo-Xiong Wu (R3); Kenneth Sperber (R4); Xin-Zhong Liang (R7)
Over the years, nine workshops were organized (see Table 1) to present and discuss collaborative research progress; and three journal Special Issues were published: 2001 and 2008 in Climate Dynamics, and 2004 in the Journal of Climate.
1. Coordinator(s)
1994-2008 Wei-Chyung Wang
2009- Huang-Hsiung Hsu and Jian-Ping Li
2. Activities
| No | Time and Place | Workshop (Place/Host) |
Remarks |
| 1 | Albany, Oct 1994 | Wei-Chyung Wang (State University of New York-Albany) |
|
| 2 | ChungLi, April 1996 | Huang-Hsiang Hsu and Wen-Shung Ko |
|
| 3 | Nanjing, March 1997 | Guo-Xiong Wu |
|
| 4 | Taipei, Nov 1998 | Huang-Hsiang Hsu |
|
| 5 | Seoul, April 2000 | Jeong-Woo Kim |
|
| 6 | Harbin, Aug 2002 | Shou-Rong Wang and Yihui Ding (National Climate Center) |
2001 Special Issue: Climate Dynamics |
| 7 | Hawaii, Feb 2004 | Bin Wang (University of Hawaii) |
2004 Special Issue: Journal of Climate |
| 8 | Nantou, Mar 2006 | Huang-Hsiung Hsu (National Taiwan University) |
|
| 9 | Fukuoka, Dec 2007 | Masahide Kimoto (University of Tokyo) |
2008 Special Issue: Climate Dynamics |
| 10 | Yinchuan, Aug 2009 | Jianping Li (Institute of Atmospheric Physics) |
The active participating groups in EAC include:
Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing
National Climate Center, China Meteorological Administration, Beijing
Department of Atmospheric Sciences, National Taiwan University, Taipei
Department of Earth Sciences, National Taiwan Normal University, Taipei
Atmospheric Sciences Research Center, State University of New York, Albany
Program for Climate Model Diagnosis and Intercomparison, Lawrence Livermore
National Laboratory, Livermore
The project has two main objectives: To assess the ability of current GCMs to simulate the EAC, including vacillations between high and low zonal index circulation, abrupt seasonal change in the atmospheric circulation and the east Asian monsoon.
To study the mechanisms and factors that cause the intraseasonal to interannual variability in the EAC, which include the dynamic and thermal effects of the Tibetan Plateau, anomalous surface boundary conditions (e.g., temperature, snow cover, soil moisture) over the Eurasian continent.
General Consideration
The study will be conducted by examining: (1) Systematic biases of the climatological mean and interannual variability of individual climate parameters, which include sea level pressure, surface temperature, wind, precipitation, outgoing longwave radiation, 500 mb height, snow/ice cover; (2) Consistency of the biases between the individual parameters; and (3) the geophysical factors and mechanisms which have dominate influences over EAC. Statistical analyses of these parameters will be performed to examine their variations and internal consistency while GCM sensitivity experiments will be conducted to identify the causes for the model biases for their further improvements.
In addition to the comparisons discussed above, it will be useful to compare moist potential vorticity (MPV), a variable which can characterize the evolution of lower tropospheric motions. MPV consists of a dynamic component (the specific absolute vorticity) and a thermodynamic component (the 3-D gradient of equivalent potential temperature). It has been demonstrated that its isobaric presentation is an excellent indicator of summer monsoon frontal rainfall.
Specific Considerations
The ZIC and SAC are large-scale phenomena that can be resolved by the resolution of the participating AMIP GCMs. It is straightforward to define the ZIC and to identify the temporal and spatial variations of SAC. Statistical techniques (such as spectrum analysis, EOF analysis, correlation analysis and EP flux) will be used to investigate ZIC and SAC variability.
It is difficult, however, to define the EAM in a GCM. We plan to study first the East Asian Summer Monsoon (EASM) with focus on the onset. For the period of mid-April through mid-June (pre-onset, onset and post-onset), Hovmoller diagrams of climatological five-days running means of a variety of parameters (temperature, precipitation, cloud, moisture and wind) for several critical regions will be compared. Note that proper spatial scales need to be considered in averaging the GCM outputs over the specified latitudinal or longitudinal zones. We plan also to study, in addition to the climatological means, the characteristics of individual years.