一个变网格大气环流模式对中国东部春季的区域气候模拟

Regional climate simulation over eastern China in spring by a variable resolution AGCM

  • 摘要: 将法国动力气象实验室发展的变网格全球大气环流模式LMDZ4在东亚地区进行加密,并使用ERA-40再分析资料进行环流强迫,对1958—2000年每年春季开展区域气候模拟,将模拟的4—5月气候平均态、年际和年代际变率与观测进行了对比。模式能够较为真实地模拟出4—5月东亚地区气候平均大气环流、降水和气温的空间分布,对对流层中、高层环流的模拟比对低层环流的模拟更接近于观测;模式对中国东部地区地面气候的模拟偏差主要表现为:中国中东部和华南地区偏暖偏湿,而华北则为偏冷偏湿。中东部地区的降水量比观测偏多约1.6 mm/d;模拟的地表气温在华北偏低约1.4℃,在中东部和华南均偏高超过0.5℃。模式对降水的模拟偏差与其模拟的低层南支西南气流和北部西北气流均偏强有关。模式对中国东部对流层,尤其是对流层中上层大气环流的年际变化具有很好的再现能力,各物理量与观测值的相关系数都在0.6以上。模式也能很好地模拟出中国东部降水和气温的年际变率,在华北、中东部和华南,观测和模拟值在1958—2000年的相关系数均在0.7以上。模式还能够模拟出20世纪70年代末出现的中东部干旱和东北地区降水增多的年代际变化特征,也能够再现黄淮流域年代际增温的现象。因此,该模式对东亚区域气候的模拟不仅对东亚春季气候平均态具有较好的再现能力,而且对中国东部春季气候的年际变率和年代际变化也具有一定的模拟能力。

     

    Abstract: A variable resolution global Atmospheric General Circulation Model LMDZ4 developed at Laboratoire de Météorologie Dynamique is used to simulate the spring climate in eastern Asia during 1958-2000. The model is forced by the ERA40 reanalysis data. The mean climate, interannual variability and interdecadal variability in AprilMay over eastern China simulated by the model are compared with the observation. The model can realistically simulate the climate distribution of the atmospheric circulation, precipitation and surface air temperature. The model has a better capability in reproducing the atmospheric circulation in the middle and upper troposphere than that in the lower troposphere. The model systematically overestimates the rainfall in the central part of eastern China and North China. The simulated biases of surface climate over eastern China show that it is in the warmer and wetter sides in the central and eastern parts of China and South China, whereas in the colder and wetter sides in North China. The simulated rainfall in central and eastern China is larger than the observation by about 1.6 mm/d. The simulated surface air temperature is lower than the observation by about 1.4℃ in North China, and higher than the observation by over 0.5℃ in central and eastern China and South China. Such biases are related to the stronger lowlevel southwest flow in South China and stronger northwest flow in North China. The model well simulated the interannual variability of the atmospheric circulation in the troposphere, especially in the middle and upper troposphere. The correlation coefficients of the variables are all above 0.6. The model well reproduced the interannual variability of the precipitation and surface air temperature in East China. The correlations between the simulation and the observation are all larger than 0.7 in North China, central and eastern China and South China. The analysis about the decadal change of the late spring climate shows that the model reproduced the interdecadal drought in central and eastern China and the interdecadal increase of the precipitation in northeastern China occurred in the late 1970s. The model also reproduced the interdecadal warming in the Huanghuai Basin. So the regional climate simulation over East Asia by this model is not only able to reproduce the mean climate status in spring, but also has a good capability in simulating the interannual and interdecadal variability of the spring climate in eastern China.

     

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