华北地区夏季降水模拟研究:区域气候模式性能评估

A simulation study on summer rainfall over North China:Evaluation of a regional climate model

利用高分辨率区域气候模式Reg CM3对华北地区1991—2002年夏季气候进行了数值模拟,对照中国台站的实测资料,对模拟的华北地区夏季降水、温度进行了较为全面的比较,以检验模式的模拟性能。对平均场的模拟结果检验认为,该区域气候模式对华北地区夏季降水的空间分布模拟存在一定的误差,河套地区及黄河以南地区降水量接近实况,沿着太行山脉及东部沿海地区降水量明显偏多。模式对温度的模拟误差较小,较好地再现了气温的空间分布特征,但山西及以北地区模拟的温度略偏低。模式能够较好地模拟出华北地区夏季降水和气温的年际变化,成功再现了该区域降水和气温的异常变化。模式能够成功模拟出该区域降水和气温日变化特征,特别是对于逐年夏季的降水日变化过程的峰值和谷值均有成功表现,对于典型年份华北地区较强降水过程中降水发生的时间、落区、强度等也有再现能力,不足的是模拟的降水量比观测偏大。对于模式误差是否与地形或模式积云对流参数化方案等有关,需要进一步探讨。

By using regional climate model( Reg CM3),summer rainfalls over North China during 1991 to2002 were simulated. The model's capability to reproduce the different time scale features of rainfall and temperature had been evaluated based on station observations. Results showed that there were some differences between the model result and the observation in the spatial distribution of summer rainfall. The model can well reproduce the rainfall over Hetao and south of Huanghe river basin,but it overestimated the rainfall in regions along Taihang Mountain and the coastal regions. The model can well reproduce the spatial pattern of temperature. The simulated temperature in Shanxi and southern regions was cooler than the observation. It also well revealed the inter-annual variation of summer rainfall and temperature,such as anomalies in some special years. The daily variation of rainfall and temperature,as well as the peak and valley value evolution of daily rainfall,were also successfully simulated. The model can also reproduce the time,location and intensity during the heavy rainfall process in typical cases. Unfortunately,the rainfallwas overestimated in the model. It requires further work to investigate whether the deficiency was caused by the complex topography or cloud-radiation parameterization scheme.