基于ASD统计降尺度的雅鲁藏布江流域未来气候变化情景

Climate Change Scenarios in the Yarlung Zangbo River Basin Based on ASD Model

青藏高原对东亚、南亚甚至全球的气候和水文循环有重要影响，模拟和分析青藏高原未来气候状况对研究东南亚区域生态、气候、水资源格局与演变趋势具有重要意义。利用ASD统计降尺度方法，对MIROC3．2_medres模式输出的降水和气温进行降尺度，并与ERA-40再分析资料进行了对比分析和评价，在此基础上分析了2046-2065年与2081-2100年三种情景下的气候变化情况。结果表明，ASD统计降尺度模型可以较好地将雅鲁藏布江流域GCM大尺度降水和气温数据降尺度到站点尺度，气温的解释方差都在90％以上，降水的解释方差也达到12％～27％；雅鲁藏布江流域未来降水年际变化不明显，年变化趋势多数小于5％；降水年内分配将更加集中，秋、冬、春季的降水减少趋势明显，最大降幅达55．58％，夏季降水显著增加，最大增幅达到30．44％；雅鲁藏布江流域未来将显著增温，21世纪中叶增温幅度为1．60～2．12℃，21世纪末期增温幅度达2．34～3．69℃；在降水与气温的双重影响下，流域水资源问题可能会变得更加严峻。

The Qinghai-Xizang Plateau （QXP） plays a key role on both hydrological cycle and climate for southern and eastern Asia. It is important to simulate and analyze future climate condition over the QXP to inves- tigate the distribution and evolution trend of ecosystems, climate and water resources for southeastern Asia. Based on ASD statistical downscaling model, climatic factors including precipitation and air temperature in the Yarlung Zangbo River （YZR） basin were downscaled to meteorological stations by using the MIROC3.2_medres data. Simulation accuracy was evaluated by comparing with the outputs of ERA --40 reanalysis. Future climate change scenarios in the periods of 2046 --2065 and 2081 --2100 were generated on the basis of ASD downscal- ing model. The results show that ASD can be applied to the YZR basin satisfactorily, being able to simulate the spatial and temporal patterns of precipitation and temperature regimes, and the explained variance of temperature exceeds 90%, while the explained variance of precipitation reaches 12% -27%. Changes of annual total precip- itation are not significant, the change trends are less than 5 % for most of scenarios, but precipitation will become more concentrated. Precipitation in spring, autumn and winter decreases remarkably, with the largest ratio of 55.58%. Precipitation in summer, however, shows a significant increasing tendency. The largest amplitude is 30.44%. Temperature over the YZR basin will increase dramatically, the amplitude is 1.60 - 2. 12℃ in the middle of 21st century, and 2.34 -3.69℃ at the end of 21st century. It showed that water resources planning in the YZR basin will become a great challenge due to the changes of precipitation and air temperature in the future.