两种Penman-Monteith公式计算草坪草参考腾发量的适用性

    Applicability of FAO56 and ASCE Penman-Monteith equations for reference crop evapotranspiration calculation on turf grass

    • 摘要: 为了揭示ASCE和FAO56两种Penman-Monteith公式在计算小时参考作物腾发量(ET0)时的差异,开展了充分供水草坪草腾发量观测试验。基于自动气象站的小时气象数据和蒸渗仪试验结果,在对比两公式计算结果差异基础上,以实测的日草坪腾发量为标准评价了2种计算公式小时ET0的日累积结果及以日的计算结果。结果表明:2种Penman-Monteith公式计算的小时ET0结果存在一定差异,ET0较高的时段差异也比较大。白天FAO56 Penman-Monteith公式的计算结果低于ASCE Penman-Monteith公式的计算结果,夜晚则正好相反,原因在于Cd取值的差异。与实测日ET0结果相比2种公式小时时段的ET0结果的累积值误差均比较大,ASCE的改进并没有使Penman-Monteith在计算结果上取得实质性的改进,相比之下以日为时段的Penman- Monteith公式(ASCE同FAO56)取得了与实测结果最为一致的效果。进一步根据实测的小时ET0数据以及更长序列的日ET0实测结果,评价FAO56 Penman-Monteith和ASCE Penman-Monteith结果的地区适用性将是今后研究内容之一。

       

      Abstract: In order to reveal the difference between hourly reference crop evapotranspiration(ET0) calculated by FAO56 Penman- Monteith equation and that by ASCE Penman-Monteith , as well as the 24-hour accumulated daily ET0, well watered lysimeter experiment were carried out on turf grass. Hourly ET0 and 24-hour accumulated daily ET0 were calculated based on hourly meteorological data and evaluated by using daily observed grass evapotranspiration derived from well watered lysimeter experiment. There was a certain difference between ET0 calculated by FAO56 Penman-Monteith equation and that by ASCE Penman-Monteith equation, and the difference was more significant when the ET0 values were relative higher. Hourly ET0 were tested to be lower for FAO56 Penman-Monteith equation than for ASCE Penman-Monteith equation in daytime, but just reversed at night. That was ascribed to the difference in Cd values. It was a pity to say that the equation mended by ASCE could not result in improvement in hourly ET0 calculation, when the 24-hour accumulated daily ET0 were compared with observed daily grass evapotranspiration. Daily ET0 calculated by Penman-Monteith equation based on meteorological data at daily time step were test to be the most consistent with that by lysimeter observed. Further evaluation of either FAO56 Penman-Monteith equation or ASCE Penman-Monteith equation was urgent in China, based on hourly or long series daily observed grass evapotranspiration.

       

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