The Necessity of Sensor Calibration for the Precise Measurement of Water Fluxes in Forest Ecosystems
The Necessity of Sensor Calibration for the Precise Measurement of Water Fluxes in Forest Ecosystems
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DOI：
10.1007/978-3-030-26086-6_2
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
S. Iida;Takanori Shimizu;Yoshinori Shinohara;S. Takeuchi;T. Kumagai
中科院分区：
文献类型：
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作者：
S. Iida;Takanori Shimizu;Yoshinori Shinohara;S. Takeuchi;T. Kumagai
在森林流域，截留损失（EI）和蒸腾（ET）占蒸散的大部分。因此，它们的精确评价对于理解和量化水文循环内的通量是必要的。ei通常由倾斗雨量计和流量计测量，而ei通常由液流技术估计。为了获得可靠的feandet估计，我们详细描述了校准翻斗雨量计和流量计以及液流技术的程序。对于倾斗式雨量计和流量计，我们先测量单尖端的静态体积，然后测量不同入流速率下单尖端体积的变化，进行动态标定。如果没有适当的校准，显著的评估误差可能在40%的低估到20%的高估之间。我们从两个地点对杉木（Cryptomeria japonica）进行了三种液流技术的校准——热耗散（TD）、热场变形（HFD）和热比（HR）方法。对真空泵产生的人工液流，证实了液通量密度（FD）在径向和方位角上的明显变化趋势。在一个站点的采样段中，TD和HFD方法没有任何高估和低估efd的趋势。而在另一个站点，TD和HFD方法至少低估了30%的efd，从而低估了30%的et， HR方法则高估了30%。因此，我们强烈建议校准翻斗雨量计、流量计和液流技术，以获得有效的feandet估计。
In forested watersheds, interception loss (EI) and transpiration (ET) constitute the majority of evapotranspiration. Accordingly, their precise evaluations are necessary to understand and quantify fluxes within the hydrologic cycle.EIis commonly measured by tipping-bucket rain gauges and flow meters, whileETis often estimated by sap flow techniques. To obtain reliable estimations ofEIandET, we describe detailed procedures to calibrate tipping-bucket rain gauges and flow meters as well as sap flow techniques. For tipping-bucket rain gauges and flow meters, we measure the one tip static volume, and then changes in the one tip amount with different inflow rates for dynamic calibration. Without proper calibration, the significant evaluation error inEIcan range from 40% underestimation to 20% overestimation. We calibrate three sap flow techniques—thermal dissipation (TD), heat field deformation (HFD), and heat ratio (HR) methods—for Japanese cedar (Cryptomeria japonica) from two sites. The clear radial and azimuthal trends in sap flux density (FD) are confirmed for the artificial sap flow generated by a vacuum pump. Among segments sampled at a site, TD and HFD methods do not have any tendencies to overestimate and underestimateFD. While at the other site, TD and HFD methods underestimateFD, and thereforeET, by at least 30%, the HR method shows a 30% overestimation. Thus, we highly recommend the calibration of tipping-bucket rain gauges, flow meters, and sap flow techniques to obtain valid estimates ofEIandET.