川滇农牧交错带参考作物蒸散量演变特征及驱动因子分析

The evolution characteristics and driving factors analysis of reference crop evapotranspiration in the agricultural and pastoral ecotone of Sichuan Province and Yunan Province

应用川滇农牧交错带24个地面观测站点1961—2015年的逐日气象资料,选用Penman-Monteith公式计算各站点逐日参考作物蒸散量(ET0)和地表湿润指数(SWI),并采用气候倾向率、反距离插值法(IDW)、Mann-KendalL突变检验、主成分回归分析等方法分析研究区的ET0和SWI时空变化特征以及各主要气象因子对不同区域参考作物蒸散量演变的影响程度。结果表明,1961—2015年,川滇农牧交错带ET0呈下降趋势,SWI呈缓慢上升趋势,1987年为ET0和SWI的突变年;湿润区与半湿润区可近似以横断山区边界作为分界线;全区四季参考作物蒸散量均在下降,冬季时空演变不显著;平均风速是影响ET0变化的主导因子,日照时数和相对湿度次之,ET0对最低气温响应最弱。

Based on the daily meteorological data of 24 ground observation stations in the agricultural and pastoral ecotone of Sichuan Province and Yunan Province from 1961 to 2015,the daily reference crop evapotranspiration(ET0)and surface humid index(SWI)of each station were calculated by Penman-Monteith formula.The temporal and spatial variation characteristics of ET0 and SWI in the study area,and the influence degree of main meteorological factors on the evolution of evapotranspiration in different areas were ana⁃lyzed using the climatic tendency rate,inverse distance weighting(IDW)interpolation,Mann-KendalL mutation test,principal com⁃ponent regression analysis and other methods.The results showed that,from 1961 to 2015,ET0 in the agricultural and pastoral ecotone of Sichuan Province and Yunan Province showed a downward trend,SWI showed a slow upward trend,and 1987 was the mutation year of ET0 and SWI.The boundary between the humid area and the semi-humid area could be approximately divided by the boundary of Hengduan Mountains.The reference crop evapotranspiration of the whole region was decreasing in four seasons,and the temporal and spatial evolution of reference crop evapotranspiration in winter was not significant.Average wind speed was the dominant factor affect⁃ing the change of ET0,followed by sunshine hours and relative humidity,and ET0 had the weakest response to the lowest temperature.