CMIP5多模式集合对南亚印度河流域气候变化的模拟与预估

利用印度河流域CRU、APHRODITE和CMIP5多模式逐月气温、降水格点数据集, 评估了CMIP5模式集合对印度河流域气候变化的模拟能力; 对多模式集合数据进行了偏差订正, 并对流域2046-2065年和2081-2100年气候变化进行了预估. 结果表明: 气候模式对流域年平均气温时间变化和空间分布特征有着较强的模拟能力, 时间空间相关系数均达到了0.01的显著性水平, 尤其对夏季气温的模拟要优于其他季节; 模式对降水的季节性波动也有着较好的模拟能力. 偏差订正后的预估结果表明, RCP2.6、4.5、8.5情景下, 相对于基准期(1986-2005年), 21世纪中期(2046-2065年)和末期(2081-2100年)整个流域年平均气温都有一定上升, 且流域上游增幅较大; 除RCP4.5情景下21世纪中期流域有弱减少趋势外, 年降水量都将有一定增长. 未来夏季持续升温将引起源区冰川的进一步消融, 春季降水对于中高海拔地区水资源的贡献将减弱; 流域北部高海拔区域冬季降水的增加有助冰川累积和上游水资源的增加, 东部高海拔区域冬季降水的减少会减少上游水资源. 两时期夏季降水都有一定的增长, 洪涝的发生风险加大; 流域暖事件和强降水事件也将可能增多.

Simulating and estimating the climate change in the Indus River Basin,South Asia,based on CMIP5 multi-model ensemble

Based on monthly temperature and precipitation grid datasets from CRU (Climatic Research Unit), APHRODITE (Asian Precipitation: Highly-Resolved Observational Data Integration Towards Evaluation) and CMIP5 (Coupled Model Inter-comparison Project phase 5) models, the simulation ability of CMIP5 models in the Indus River Basin (IRB) is evaluated for the period 1961-2005. For improving the simulation ability, the systematic bias between CMIP5 and CRU/APHRODITE is corrected by the equidistant CDF matching method (EDCDFm) firstly and then the possible change of climate change is estimated in the IRB during 2046-2065 and 2081-2100 subsequently. The results show that the CMIP5 multi-model ensemble can capture the temporal variation and the spatial distribution characteristics of annual mean temperature quite satisfactory, with temporal and spatial correlation between the CMIP5 and CRU reaching the significant level of 0.01, and summer temperature simulation results are obviously better than other months. On the other hand, CMIP5 ensembles can also reproduce seasonal variation of precipitation quite well. Based on the bias-corrected results, it is estimated that the annual averaged temperature over the whole basin will continuously increase under Scenarios RCP2.6, 4.5, 8.5 during 2046-2065 and 2081-2100 relative to those during 1986-2005, with the maximum increasing scope in the upstream areas. Annual precipitation will also increase with the exception of weak decrease during mid-21st century under Scenario RCP4.5. The persistently rising of summer temperature might cause further glacier ablation, and impact the local freshwater availability. The contribution of spring precipitation to water resources in the middle and high altitude areas will decrease. Increase in precipitation in northern high altitude areas will be favorable to glacier accumulation and increase water resources, while the decreasing precipitation in eastern high altitude areas will reduce water resources. Summer precipitation almost increases over the whole basin during both mid and late 21st century. The risk of flood disasters will increase. It is estimated that warm events and heavy rainfall events may increase in the Indus River Basin as well.