The performance of evapotranspiration (ET) temporal scaling methods is affected by a number of factors. This paper compares the statistical characteristics of actual ET data measured by Lysimeter with ET data estimated on the basis of temporal scaling models. The study shows that on an "hourly-to-daily" scaling basis, the measured daily ET data show a closer agreement with the ET data estimated on the basis of surface resistance using morning measurements than with ET data estimated on the basis of evaporative fraction and crop coefficient. Additionally, the observed daily ET data show a closer agreement with ET data estimated on the basis of crop coefficient by using aftemoon measurements than with ET data estimated using evaporative fraction and surface resistance. On a "daily-to-seasonal" scaling basis. the measured ET data show a higher correlation with ET data estimated on the basis of crop coefficient than that with data estimated on the basis of evaporative fraction and surface resistance. From the view of these results, we recommend considering the particular weather region, crop growing conditions, soil moisture content, temporal scale and observation facilities available before selecting an ET temporal scaling method for a given site.%利用蒸渗仪实测的冬小麦生育期ET数据,对比分析基于蒸发比、作物系数和冠层阻力的不同ET时间尺度扩展方法的估算效果.结果表明,对小时到日尺度的ET时间扩展而言,利用当地时间上午时段(10:00-11:00)的ET实测数据,基于冠层阻力的日ET尺度扩展值估算效果要优于基于蒸发比和作物系数的效果,而利用下午时段(14:00-15:00)的ET实测数据,基于作物系数的日ET尺度扩展值估算效果要优于基于蒸发比和冠层阻力的效果,对于从典型日到生育期尺度的ET时间扩展,基于作物系数的生育期ET尺度扩展值估算效果要好于基于蒸发比和冠层阻力的效果.应根据当地的气候气象条件、作物种植状况、时间尺度扩展类型、土壤水分和ET观测设施种类等因素,选择适宜的ET时间尺度扩展方法.
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