气候变化背景下汾渭平原参考作物蒸散量的时空变化与归因分析

Spatiotemporal variations and attribution analysis of reference evapotranspiration in the Fenwei Plain under climate change

参考作物蒸散量(ET_(0))是估算植被生态需水量的关键数据。气候变化背景下,不同区域的ET_(0)变化趋势各有不同,从区域尺度研究ET_(0)的时空变化与归因分析更有利于变化环境下区域的农业用水管理和生态需水量估算。本研究基于第六次国际耦合模式比较项目(CMIP6)发布的最新气候数据和高精度栅格数据,分析了汾渭平原年均ET_(0)在历史时期(1985—2015年)和未来时期(2030—2060年)的变化趋势、空间分布以及气象要素对ET_(0)变化的贡献。结果表明:CMIP6的气象数据经偏差校正后可用于预测ET_(0),且多模式集合方法的预测精度(R^(2)为82.9%,均方根误差为14.9 mm)高于单个气候模式的精度。汾渭平原ET_(0)在历史时期呈显著下降趋势;在未来时期的SSP245和SSP585情景下分别呈不显著上升和显著上升趋势。饱和水汽压差在历史和未来时期对ET_(0)变化的贡献率均最大,是气候变化条件下影响汾渭平原ET_(0)变化的首要气象要素,太阳净辐射和风速是历史时期影响ET_(0)变化的重要气象要素,温度和风速是未来时期影响ET_(0)变化的重要气象要素。这些气象要素的较大贡献是由于其具有较大的多年相对变化率,而不是对ET_(0)有高度的敏感性。未来时期SSP245和SSP585情景下的汾渭平原ET_(0)相比历史时期分别增加4.2%和3.1%。汾渭平原ET_(0)的变化趋势、相对变化的空间分布差异主要表现在平原的东部与西部地区之间。本研究的高精度ET_(0)时空分布结果可为汾渭平原地区制定应对气候变化的适应性措施提供数据参考。

Reference crop evapotranspiration(ET_(0))is a crucial variable for estimating the ecological water demand of vegetation.Under climate change,the trends of ET_(0) change vary in different regions.The study of spatial and temporal variations in ET_(0) and attribution analysis at the regional scale is more conducive to the regional agricultural water management and ecological water demand estimation under the changing environment.We analyzed the change trend,spatial distribution and the contribution of meteorological factors to annual ET_(0) change of the Fenwei Plain during a historical period(1985-2015)and a future period(2030-2060)based on the latest climate data and high-precision grid data from the Sixth International Coupled Model Intercomparison Project(CMIP6).The results showed that the meteorological data from CMIP6 could be used for the prediction of ET_(0) after bias correction,and that the prediction accuracy of the multi-model ensemble approach(R^(2) of 82.9%,RMSE of 14.9 mm)was higher than that of a single climate model.ET_(0) in the Fenwei Plain showed a significant decreasing trend in the historical period,but a non-significant increasing and significant increasing trend in the future period under the SSP245 and SSP585 scenarios,respectively.The vapor pressure deficit had the largest contribution to the ET_(0) change in both the historical and future periods,and was the primary meteorological factor affecting the ET_(0) change in the Fenwei Plain under the climate change.Solar radiation and wind speed were important meteorological factors affecting the ET_(0) change in the historical period,while temperature and wind speed were the important meteorological factors affecting the ET_(0) change in the future period.The meteorological factors that had great contribution to ET_(0) change were due to the larger multi-year relative change rates,rather than the high sensitivity of these meteorological factors to ET_(0).The ET_(0) of the plain under the SSP245 and SSP585 scenarios increased by 4.2% and 3.1% in the future period,respectively,compared with the historical period.The differences in the spatial distribution of the result were mainly from the eastern and western regions of the plain.Based on the high-precision spatial and temporal distribution of ET_(0),the spatial and temporal data could be used as a reference for the development of various adaptation for climate change in the Fenwei Plain.