基于CMIP5模式的黑河流域潜在蒸散量预估

蒸散发是干旱内陆河流域水资源的主要耗散途径。预估黑河流域未来潜在蒸散量（ET₀）可为气候变化条件下流域水资源的优化管理提供基础数据支撑。使用1960—2014年黑河流域气象数据，采用FAO-56Penman-Monteith公式计算流域潜在蒸散量；基于同期NCEP（美国环境预报中心）再分析资料及2006—2100年CMIP5中CNRM-CM5模式的RCP4.5、RCP8.5路径预测数据，经统计降尺度模拟与偏差校正，预估了流域未来潜在蒸散量；通过旋转经验正交函数将流域各划分为3个子区，进行子区及全流域Mann-Kendall未来趋势分析。结果显示：（1）NCEP再分析资料与流域潜在蒸散量建立的逐步回归降尺度模型模拟效果好，经CNRM-CM5模式模拟及偏差校正，适宜于预估黑河流域未来潜在蒸散量。（2）预估RCP4.5路径流域2021—2050年、2071—2100年年均潜在蒸散量较1971—2000年分别增加3.49%、6.11%，RCP8.5路径分别增加4.64%、10.07%，RCP8.5路径增幅高于RCP4.5路径。（3）利用旋转经验正交函数可将两种路径流域未来蒸散量划分为3个子区，RCP4.5、RCP8.5路径黑河流域Ⅰ区潜在蒸散量各为不显著、显著的下降趋势，两种路径下Ⅱ区、Ⅲ区及全流域均为显著上升趋势。

Prediction and Trend of Future Potential Evapotranspiration in the Heihe River Basin Based on CMIP5 Models

Evapotranspiration is the main dissipation of water resources in arid inland river basin. Future potential evapotranspiration (ET₀) prediction can provide basic data for water resources optimization and management under climate change in the Heihe River Basin (HRB). Three processes could be classified in this study. Firstly,ET₀ was calculated by FAO-56 Penman-Monteith equation based on metrological data from 1960 to 2014 in HRB. Secondly,future ET₀ was predicted by statistical downscaling and deviation regulation based on NCEP reanalysis data from 1960 to 2014, and CMIP5 CNRM-CM5 model from 2006 to 2100 under RCP4.5 and RCP8.5 pathways.Finally,three subareas were divided by rotated empirical orthogonal function (REOF) and future trends were analyzed by Mann-Kendall tests for the three subareas and whole HRB.The conclusions showed that:(1)The stepwise regression statistical downscaling models built by NCEP reanalysis data and calculated ET₀ from 1960 to 2014 were suitable for predicting future ET₀ of HRB by CNRM-CM5 model simulation and deviation regulation. (2)Annual average ET₀ of 2021-2050, 2071-2100 would increase 3.49%, 6.11% than that of 1971-2000 separately under RCP4.5 pathway,while the percentage were 4.64%, 10.07% under RCP8.5 pathway.The increasing amplitude of RCP8.5 was greater than that of RCP4.5. (3)Three subareas of future ET₀ were divided by REOF under both pathways.Insignificantly decreasing trend was detected for area I under RCP4.5 pathway, while the trend under RCP8.5 pathway was significant. Significantly increasing trends were detected for area Ⅱ, Ⅲ and whole HRB under both pathways.