陆面过程对中国夏季降水影响的模拟研究

There is a clear understanding that land surface processes play an important role in the climate change and climate anomalies. Especially over China, where is the key region for the land-air interaction, the anomalies in the land surface characteristics (e.g., soil moisture, snow cover, etc.) can exert large influence on the summer monsoon rainfall. However, there is lack of systematic researches on the impact of land surface processes on the regional climate over East Asia..By using the observational data for the snow cover over Tibetan Plateau, together with the NCEP reanalysis data, the influences of the snow cover over the Tibetan Plateau on Asian summer monsoon and the associated rainfall have been systematically studied by composed analysis and numerical experiments, and the possible mechanism of this impact has been revealed as follows: more (less) snow cover over the Tibetan Plateau ? weak (strong) surface heating in spring and summer ? weak (strong) upward motion and strong (weak) environmental wind ? unfavorable (favorable) condition for transporting surface sensible heating from near-surface layers to upper layers ? weak (strong) tropospheric heating ? low (high) tropospheric temperature surrounding the Tibetan Plateau ? weak (strong) tropospheric temperature contrast of the Tibetan Plateau in spring and summer ? weak (strong) Asian summer monsoon ? flood (drought) tendency over Yangtze river valley..Meanwhile, the impact of the springtime soil moisture over South China on the summer rainfall anomalies has also been investigated by the case study for year 1998. Numerical study shows that, the wet anomalies during springtime over South China will lead to positive rainfall anomalies over Yangtze River valley, and the sensitivity of the model to the initial soil moisture is seasonally dependent, with stronger dependence for spring and summer time, and relative weaker dependence for autumn and winter. Furthermore, by using the IAP dynamical climate prediction system, the impact of the initial soil moisture on the predictive skill has been discussed by conducting two sets of ensemble hindcast experiments, and the comparison result shows that, with the incorporation of the initial soil moisture information, the predictive skill for IAP climate prediction system can be increased in some extent. And this may further suggest the importance for the development of land data assimilation system for the climate prediction. .

利用陆表状况观测资料和气候模式研究东亚地区陆面状况的异常对东亚夏季风降水的影响，揭示陆面过程对我国夏季旱涝形势的影响及其作用机制。同时利用中科院大气物理所现有的短期气候距平预测系统，通过引入陆面状况的初始化对原有的系统进行改进，并对1998年我国特大洪涝灾害进行后报试验，以期提高我国灾害气候预测水平，增强我国防灾、减灾的能务。