Simulation of the east asian summer monsoon using a variable resolution atmospheric GCM
Simulation of the east asian summer monsoon using a variable resolution atmospheric GCM
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DOI：
10.1007/s00382-001-0214-8
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发表时间：
2002-06
期刊：
影响因子：
4.6
通讯作者：
Tianjun Zhou;Z.-X. Li
中科院分区：
文献类型：
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作者：
Tianjun Zhou;Z.-X. Li
用法国Météorologie Dynamique实验室发展的变分辨率全球大气环流模式(GCM)模拟了东亚夏季风(EASM)。使用的版本有一个以中国为中心的局部缩放。本研究验证了该模式再现东亚夏季风基本特征的能力。文中还系统地讨论了ECMWF再分析资料揭示的东亚季风行为，为观测提供了证据。模式对东亚夏季风的平均状态有较好的刻画，包括大尺度季风气流、季风经向环流、越赤道低空急流、南中国海季风槽、澳大利亚地面冷高压和高空东北回流。虽然模式在模拟大尺度季风气候方面的表现令人鼓舞，但主要的不足之处在于降雨。模拟中遗漏了长江流域观测到的明显雨带。这在本质上是由于季风分量的弱复制，并与西太平洋副热带高压的弱直接相关，从而导致西南季风在其西侧形成脆弱的副热带季风，导致西南季风流与中纬度西风的辐合较弱。高压的过度西伸和扭曲的印度低压也使得热带西南季风对长江流域水汽辐合的贡献在模式中偏弱。高原加热不足和由此产生的弱海陆热力对比是造成季风复制较弱的原因。模式对高原上空低层云层的处理不足，而不是对高原地形的水平分辨率和相关刻画的不足，导致高原加热不足。与采用规则粗网格模型的模拟结果比较表明，局部变焦技术在总体上改善了EASM模拟。
The East Asia summer monsoon (EASM) is simulated with a variable resolution global atmospheric general circulation model (GCM) developed at the Laboratoire de Météorologie Dynamique, France. The version used has a local zoom centered on China. This study validates the model's capability in reproducing the fundamental features of the EASM. The monsoon behaviors over East Asia revealed by the ECMWF reanalysis data are also addressed systematically, providing as observational evidence. The mean state of the EASM is generally portrayed well in the model, including the large-scale monsoon airflows, the monsoonal meridional circulation, the cross-equatorial low-level jets, the monsoon trough in the South China Sea, the surface cold high in Australia, and the upper-level northeasterly return flow. While the performance of simulating large-scale monsoonal climate is encouraging, the model's main deficiency lies in the rainfall. The marked rainbelt observed along the Yangtze River Valley is missed in the simulation. This is due to the weakly reproduced monsoonal components in essence and is directly related to the weak western Pacific subtropical high, which leads to a fragile subtropical southwest monsoon on its western flank and results in a weaker convergence of the southwest monsoon flow with the midlatitude westerlies. The excessively westward extension of the high, together with the distorted Indian low, also makes the contribution of the tropical southwest monsoon to the moisture convergence over the Yangtze River Valley too weak in the model. The insufficient plateau heating and the resulting weak land-sea thermal contrast are responsible for the weakly reproduced monsoon. It is the deficiency of the model in handling the low-level cloud cover over the plateau rather than the horizontal resolution and the associated depiction of plateau topography that results in the insufficient plateau heating. Comparison with the simulation employing regular coarser mesh model reveals that the local zoom technique improves, in a general manner, the EASM simulation.