Thermal infrared imaging of conifer leaf temperatures: Comparison to thermocouple measurements and assessment of environmental influences
Thermal infrared imaging of conifer leaf temperatures: Comparison to thermocouple measurements and assessment of environmental influences
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DOI：
10.1016/j.agrformet.2017.10.010
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发表时间：
2018
影响因子：
6.2
通讯作者：
Young-il Kim;C. Still;D. Roberts;M. Goulden
中科院分区：
文献类型：
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作者：
Young-il Kim;C. Still;D. Roberts;M. Goulden
热红外（TIR）成像为生态学和生物气象学研究提供了一个潜在的强有力的工具，但在多变的室外环境中植物表面温度的TIR成像的准确性一直很差。本研究评估了使用热像仪的出厂默认设置对针叶树进行TIR测量的准确性，并开发了一种采集后数据处理方法，以纠正偏离出厂默认设置的环境条件下的测量结果。我们进行了为期42天的测量活动在科瓦利斯，俄勒冈州在2014年春季，重点是冠层温度的高贵冷杉（冷杉procera），包括同时收集气象数据和叶片温度测量与热电偶阵列。然后，我们开发了经验函数的温度校正，更好地占发射率，大气和反射温度。使用出厂设置的原始TIR温度平均为8.6 ± 5.6 °C（范围为−4.2至25.4 °C），原始TIR温度与热电偶温度相差1.4-1.6 K。TIR温度通常是准确的，除了在叶温低于5 °C时的低温偏差。TIR温度校正将此偏差降低到相对于热电偶的<1.0 K平均误差。我们的研究结果表明，TIR测量可以被校正，以更准确地量化冠层温度，这种校正的重要性增加在更极端的环境条件下，如较冷的时期。
Thermal infrared (TIR) imaging provides a potentially powerful tool for ecological and biometeorological research, but the accuracy of TIR imaging of plant surface temperature in a variable outdoor environment has been poorly characterized. This study evaluated the accuracy of TIR measurements of a conifer tree that were made using the thermal camera’s factory default settings, and developed a post-collection data processing method to correct measurements for ambient conditions that depart from the factory default settings. We conducted a 42-day measurement campaign in Corvallis, Oregon during spring 2014 that focused on the canopy temperature of a noble fir (Abies procera) and included the simultaneous collection of meteorological data and leaf temperature measurements with an array of thermocouples. We then developed empirical functions for temperature corrections that better accounted for emissivity, and atmospheric and reflected temperature. The original TIR temperatures using the factory settings averaged 8.6 ± 5.6 °C (−4.2 to 25.4 °C in range), and the original TIR temperatures differed from the thermocouple temperatures by 1.4–1.6 K. The TIR temperatures were generally accurate, except for a low temperature bias at leaf temperatures below 5 °C. TIR temperature corrections reduced this bias to a <1.0 K mean error relative to the thermocouples. Our results show that TIR measurements can be corrected to more accurately quantify canopy temperature, and that the importance of this correction increases under more extreme ambient conditions, such as colder periods.