中文摘要：

利用NCAR公用陆面模式CLM3（Common Land Model 3），以1979--2003年NCEP／DOE再分析资料（Reanalysis～2）作为外界强迫，对在分辨率为0．5°纬度×0．5°经度下中国区域进行独立（offline）模拟试验，并分析了土壤湿度对全球变暖的响应。模拟结果显示：土壤湿度随深度的增加调整（spin—up）到稳态时间加长，最长可高达20年，这说明模式陆面过程对土壤初始状态的敏感性。模拟结果与台站实测资料及NCEP再分析资料输出的土壤湿度的对比表明，季节与年际变化及其空间分布基本一致。我们的结果还显示，随着近年来气候逐渐变暖，包括中国北方（30°N以北）在内的东亚北部地区夏季土壤湿度有逐渐减少趋势，最多减少15（mm3·mm-3）·（100a）-1。

英文摘要：

Hydrological process related to soil moisture plays an important role in determining regional and global climate. However, a wide range and long-term observation of soil moisture is extremely sparse. In order to investigate energy and hydrological cycles between soil, vegetation and atmosphere, land process models are often used to produce soil moisture data which have physical consistency and spatiotemporal continuity. In this study, using a state-of-art Community Land Model （CLM, version 3） devel- oped by the National Center for Atmospheric Research （NCAR）, we simulate Chinese soil moisture and its possible response to global warming through a 10ng off-line experiment under 0.5°（longitude） N 0.5°（latitude） resolution and real atmospheric forcing of the NCEP/DOE reanalysis during 1979--2003. The main conclusions can be summarized as follows： （1） The spin-up time of soil moisture varies with the depth of soil layers. The deeper a soil level is, the longer the soil moisture reaches its equilibrium state. The equilibration time needs over 20 years at soil levels below 1.5 m. This shows that the soil moisture is sensitive to its initial condition in the land process model that a long spin-up process is necessary in climate modeling studies related with land hydrological processes. （2） By comparing the CLM-simulated soil moisture with observed values at a few representative statiOns with different types of soil property and reanalysis-obtained grid-box soil moisture, we find that the CLM can reasonably reproduce the seasonal variation and interannual variability as well as the horizontal and vertical patterns of soil moisture in East Asia including China. （3） On the basis of the CLM-simulated soil moisture, an analysis of the linear trend during the 20 years shows that it is getting drier in most regions of East Asia including northern China north of 30°N but wetter in southern China and the Tibetan Plateau, especially in summer. The regionally-averaged soil moisture indicates a signi