Vol. 18 No. 1 Advances in Atmospheric Sciences January 2001 Validation of IAP94 Land Surface Model over the Huaihe River Basin with HUBEX Field Experiment Data m Yang Xiaosong (~s]',~z~), Lin Zhaohui (]~) Dai Yongjiu (~7~x~) and Guo Yufu (~/~) LASG, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029 (Received March 17, 2000; revised June 7, 2000) ABSTRACT Off-line experiments have been conducted with IAP94 land surface model on different surface types (cropland, forest and paddy field) in different seasons (spring, summer and autumn) over the Huaihe River basin. The simulated energy fluxes and canopy temperature by IAP94 agree quite well with the observations, simulation results also show that IAP94 can successfullysimulate the tendency of total soil water content va- riation. The comparison results between simulation and observation indicate that strong evaporation at the paddy field in summer should be paid more attention to within the land surface models, and modeVs per- formance leads to the conclusion that IAP94 is capable of reproducing the main physical mechanisms gov- erning the land-surface processes in the East Asian semi-humid monsoon region. Key words: Land surface process, Model validation, Off-line experiments I. Introduction Many studies have shown that the land surface process plays an important role in the climate system, especially in the East Asian monsoon region, and the impact of land surface processes on the monsoon system is quite significant (e.g., Charney, 1975; Meehl, 1994; Lin et al., 1996; Li and Yanai, 1996; Yang et al., 1996). When incorporating the complicated land surface processes into the climate model, the modeVs capability in reproducing the modern climate, including monsoon circulation and its precipitation, can be greatly improved (e.g., Lin and Zeng, 1997; Dai et al., 1998; Ding et al., 1998). In order to identify the parameterization strengths and inadequacies of the existing land--surface models, and to improve the parameterization of the continental surface, espec- ially hydrology, energy, momentum and carbon exchanges with the atmosphere, the Project for the Intercomparison of Land-surface Parameterization Schemes (PILPS) has been con- ducted since 1992 (e.g., Henderson-Sellers et al., 1993), which emphasizes sensitivity studies with the existing land surface models, intercomparisons between these models and the devel- opment of areally extensive datasets for their testing and validation. All participating Land Surface Models (LSMs), including IAP land surface model (IAP94), have been evaluated and calibrated by intercomparison with many observational datasets over different surface types, such as ARME from Brazil, Cabauw from the Netherlands, HAPEX-MOBILHY from 0)National Key Porgramme for Developing Basic Sciences (G1998040900-partl) and Supported by the National Natural Science Foundation of China (No: 49794030 and 49823002).