嘉陵江流域参考蒸散的年际变化趋势及成因分析

Interannual Change and Attribution of Reference Evapotranspiration over Jialingjiang Basin

利用嘉陵江流域1960—2013年逐日气象数据,计算该流域参考蒸散(ET_0),应用Mann-Kendal方法及突变方法检测ET_0的变化趋势及突变点,应用偏导系数法揭示了ET_0变化原因。结果表明:(1)在1960—2013年,嘉陵江流域平均ET_0减小,减小斜率是0.43 mm/a。ET_0的年际变化较为剧烈,整个流域平均ET_0在1960—2013年间经历了高—低—高的3个变化阶段。在1981年ET_0的变化趋势发生了突变,嘉陵江流域ET_0的变化过程(1960—2013年)可以分为2个阶段,1960—1981年流域的整体ET_0均值变化波动较小(0.44 mm/a),1982—2013年增加趋势明显(2.62 mm/a)。不同时间尺度统计,流域北部均属于ET_0增加区域;(2)"蒸发悖论"现象存在时空差异,从整个研究时段看,流域整体存在"蒸发悖论"现象,1981年前后两个时段分别统计,存在"蒸发悖论"现象的气象站和区域较少;(3) 1960—1981年引起嘉陵江流域ET_0变化的主导因子是风速和太阳辐射,1982年后由于气候变暖趋势明显,温度上升对整个流域的ET_0增加发挥着主导作用。

As a dominant consumer for solar radiation, evapotranspiration is a primary link for the surface energy balance and component of hydrologic cycle. In recent years, the new dynamics regarding reference evapotranspiration(ET0) have been detected in some regions in the world. However, whether a new dynamics of ET0 exist in Jialingjiang River Basin was not available in the literature. In addition, quantitative attribution of changes in ET0 to key climatic factors was also not available in the literature. Temporal patterns in ET0 and related driving factors over Jialingjiang Basin were investigated in the period 1960—2013 based on daily data from 30 standard meteorological stations. The non-parametric Mann-Kendal method was used to detect trend of mean annual ET0. Some change-point year detection including Pittett, moving T test and Cumulative Sum algorithm, were applied to identify abrupt year. For the purpose of ET0 spatialization, Kringing interpolation method also was utilized. The results showed that:(1) the mean ET0 reduced at the rate of 0.43 mm/year, and the mean ET0 went through high-low-high phases;the mean ET0 changed abruptly around 1981, the mean ET0 slightly increasing by 0.4 mm/year between 1960—1981, while an obvious increasing trend at 2.62 mm/year appeared between 1982—2013;(2) ‘evaporation paradox’ phenomenon was characterized by spatial and temporal disparities, ‘evaporation paradox’ phenomenon could be detected in the period 1960—2013 when comparing the mean ET0 and air temperature trends;however, with respect to the period 1960—1981 and 1982—2013, the areas where ‘Evaporation paradox’ phenomenon could be detected were small;(3) in the period from 1960 to 1981, wind speed and solar radiation were the leading climatic variables to change ET0;During 1982—2013, air temperature was the dominant factor to increase ET0 because of climate warming.