气候模式的年际变率和可预测性

INTERANNUAL VARIABILITY AND PREDICTABILITY IN A GLOBAL CLIMATE MODEL

该文研究了大气物理研究所９层格点大气环流模式模拟的年际气候变率，一种试验采用多年平均的观测海温作为下边界条件，另一种试验是有年际变化的实测海温作为下边界条件，两种试验的年际变率分别记为Ｖ１和Ｖ２，其比值Ｒ（Ｖ２／Ｖ１）则可代表以实测海温为边界条件的模式可预测性．研究结果显示：两种试验的年际变率差异主要在热带区，Ｖ２一般大于Ｖ１，并且更接近实际变率；气温和高度场的可预测性在热带区较高，在热带以外区域通常较低，而且，高层的可预测性大于低层；降水的可预测性在全球都比较低，只在赤道某些区域略高．这一结果说明，改进年际气候预测的出路在于改进陆面过程的模拟和观测，而陆面过程中的初始异常（积雪、反照率、土壤湿度、土壤温度等）也应考虑在动力预测系统之中．

The interannual variabilities of the climatological simulation (V1) and the AMIP (Atmospheric Model Intercomparison Project) simulation (V2) by the IAP 9 Level Atmospheric General Circulation Model were studied. Based on the analysis of ratio (R=V2/V1) of above two simulations the predictability of the model on the interannual climate variation was studied as well. The results show that V2 is bigger than V1 generally and V2 is more comparable to the real variability of the atmosphere, the major difference between V1 and V2 is in the tropics, for temperature and geopotential height the predictability is higher in the tropics while in the extratropics there is almost no predictability, and predictability is bigger in upper level than in lower level, the predictability for precipitation is generally lower in the globe, and generally the predictability is higher in the tropical East Pacific for the lower level. This study suggests that the possible way of increasing the model predictability is the improvement of land surface process modelling and the inclusion of the initial anomaly of the land surface conditions (snow cover, albedo, soil moisture and temperature, etc.) as the forcing factor for climate modelling and prediction.