基于CMIP6气候模式对长江流域四川段的未来降水变化预估与分析

Prediction and Analysis of Future Precipitation Changes in the Sichuan Section of the Yangtze River Basin Based on the CMIP6 Climate Model

[目的]了解和掌握气象时空变化,合理预估气候变化的未来趋势,可为区域应对措施的制定提供重要的理论依据。[方法]以长江流域四川段作为研究区,基于1980—2014年实测站点资料进行数据分析,采用偏差订正后的国际耦合模式比较计划第六阶段(CMIP6)中情景齐全的GCM预估3个未来假定气候情景模式(SSP1-2.6,SSP2-4.5,SSP5-8.5),分析了区域内降水气候变量的变化情况。[结果](1)气候模式模拟长江流域四川段降水量的结果存在一定程度的低估,在时间尺度上表现为月尺度>季尺度>年尺度。(2)对气候模式进行校正和评估后,数据更加符合实际情况,分位数映射法对气候模型数据的校正是很有效的。(3)相对于基准期(1980—2014年),研究区域未来降水量在3种情景下均高于历史时期,表现为SSP5-8.5>SSP2-4.5>SSP1-2.6。(4)降水量增加较大的区域主要位于研究区的西北部,呈现西部低东部高的空间格局。[结论]气候模式对研究区未来降水变化的预估结果为整体呈增长趋势,但存在一定程度低估。

[Objective] Understanding and grasping the temporal and spatial changes in meteorology and reasonably predicting the future trend of climate change can provide an important theoretical basis for the formulation of regional response measures.[Methods] The Sichuan section of the Yangtze River Basin was selected as the research area.Data analysis was conducted based on measured station data from 1980 to 2014.Three future hypothetical climate scenario models(SSP1-2.6,SSP2-4.5,SSP5-8.5) were estimated using the GCM with complete scenarios in the sixth phase of the International Coupled Model Comparison Plan(CMIP6) after bias correction,and the changes in precipitation climate variables within the region were analyzed.[Results](1) There is a certain degree of underestimation of precipitation simulation in climate models,with monthly scale>seasonal scale>annual scale in terms of time scale.(2) After the calibration and evaluation of the climate model,the data are more consistent with the actual situation,and the quantile mapping method is very effective for the calibration of the Climate model data.(3) Compared to the benchmark period(1980—2014),the future precipitation in the study area is higher than the historical period under three scenarios,with SSP5-8.5>SSP2-4.5>SSP1-2.6.(4) The areas with significant increases in precipitation are mainly located in the northwest of the study area,showing a spatial pattern of low level in the west and high level in the east.[Conclusion] The climate model′s prediction of future precipitation changes in the study area shows an overall increasing trend,but there is underestimation to a certain extent.