拉萨河流域未来降水情景预估

Projection of Future Precipitation in the Lhasa River Basin

摘要: 拉萨河流域是西藏地区政治、经济、文化中心，在全球气候变暖影响下，流域气候变化显著，针对拉萨河流域开展气候变化研究具有重要意义。本文基于气象站点实测数据和ERA-40与MIROC3.2_medres大尺度网格数据，采用统计降尺度模型Automated Statistical Downscaling(ASD)，对拉萨河流域日降水量进行降尺度研究，在此基础上分析了流域2046~2065年与2081~2100年降水量变化情景。结果显示：ASD模型能够较好地模拟流域降水基本特征，各站点的解释方差(R²)达到13%~22%，率定期与验证期的均方根误差(RMSE)分别控制在0.25与0.53以内。未来两个时期流域降水格局变化显著，年降水量将减少10.55%~17.25%。降水年内分配变得更加集中，夏季降水呈显著增加趋势，变化幅度为19.03%~59.02%；春、秋、冬季降水呈显著减少趋势，减小幅度为18.43%~40.93%。

Abstract: Under the impact of global warming, the Lhasa River Basin (LRB), located at the political, economic, and cultural center of Tibetan region, is experiencing significant climate change. It is important to undertake the climate studies over LRB. On the basis of observed precipitation at meteorological stations, ERA-40 reanalysis and MIROC3.2_medres data, statistical downscaling model—Automated Statistical Downscaling (ASD) was employed to simulate historical daily precipitation. Future precipitation scenarios for the periods of 2046 - 2065 and 2081 - 2100 were generated by using ASD model. Results show that ASD model can simulate the basic features of precipitation well, with the explanation variance (R²) of each station reaching 13% - 22%. Root mean square errors (RSME) during calibration and validation periods are around 0.25 and 0.53, respectively. Precipitation regime will change significantly in the future. Total amount of annual precipitation will decrease by 10.55% - 17.25%. Future precipitation will become more concentrated. In summer, precipitation will increase evidently, and the amplitude of change is 19.03% - 59.02%, while precipitation in spring, autumn and winter will experience obvious decreasing, with the ratio of 18.43% - 40.93%.