Surface Energy Partitioning and Evaporative Fraction in a Water-Saving Irrigated Rice Field
Surface Energy Partitioning and Evaporative Fraction in a Water-Saving Irrigated Rice Field
复制标题
节水灌溉稻田的表面能分配和蒸发分数
DOI：
10.3390/atmos10020051
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发表时间：
2019-02-01
期刊：
影响因子：
2.9
通讯作者：
Lv, Yuping
中科院分区：
文献类型：
--
作者：
Liu, Xiaoyin;Xu, Junzeng;Lv, Yuping
稻田地表能量分布和潜热通量(LE)与有效能的比值，称为蒸发分数(EF)，是理解水和能量过程的关键。预计在节水灌溉措施下，它们将以不同的方式因应土壤水分状况的变化而变化。本研究基于涡旋协方差系统测量的数据，对2015和2016两年的节水灌溉稻田能量分配的日变化和季节变化进行了检验，并用EF方法对能量平衡进行了修正。土壤热通量(G)值与感热通量(HS)值在大小上相似，都约占能量输入的5%。G和HS的大小均显著低于LE。一般来说，节水灌溉稻田的生态足迹大于其他生态系统的生态足迹，变化范围较窄，在0.7~1.0之间。EF昼夜下降至中午，下午缓慢回升至日落。发现在10：00到14：00之间变化较小。在季节上，节水灌溉稻田干湿交替的土壤水分条件导致了生态足迹的变化。LE通量是有效能量的最大组成部分，EF大多大于0.9。EF一直呈上升趋势，从分蘖后期到乳熟期一直保持较高水平，之后呈下降趋势。乳熟期EF值最大，接近1.0。节水灌溉稻田蒸散量的估算结果将为利用卫星蒸散量估算日或长时间尺度蒸散量提供依据。
Surface energy distribution in paddy fields and the ratio of latent heat flux (LE) to available energy, termed as the evaporative fraction (EF), are essential for an understanding of water and energy processes. They are expected to vary in different ways in response to changes in the soil moisture condition under water-saving irrigation practice. In this study, the diurnal and seasonal variations in energy distribution were examined based on the data measured by the eddy covariance system and corrected with enforcing energy balance closure by the EF method in water-saving irrigated rice paddies in 2015 and 2016. Soil heat flux (G) values were similar in magnitude to sensible heat flux (Hs) values, with both accounting for approximately 5% of the energy input. Both magnitudes of G and Hs were significantly lower than that of LE. Generally, EF in water-saving irrigated rice paddies was larger than that of other ecosystems, and varied within a narrow range from 0.7 to 1.0. Diurnally, EF decreased till noon and then increased slowly in the afternoon till sunset. It was found be less varied between 10:00 and 14:00. Seasonally, the alternative drying-wetting soil water conditions in water-saving irrigated rice paddies resulted in a change in the variation of the EF. The LE flux is the largest component of available energy, with EF being mostly higher than 0.9. EF, increasing consistently till the tillering stage, remaining high from the late tillering to milk stage, and then following a declining trend. The maximum EF (approaching 1.0) was found in the milk stage. The results of EF in water-saving irrigated rice paddies will be helpful for estimating daily or long temporal scale evapotranspiration (ET) by the EF method based on satellite-derived ET.