Assessing Inter-Sensor Variability and Sensible Heat Flux Derivation Accuracy for a Large Aperture Scintillometer
Assessing Inter-Sensor Variability and Sensible Heat Flux Derivation Accuracy for a Large Aperture Scintillometer
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评估大孔径闪烁计的传感器间变异性和显热通量推导精度
DOI：
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发表时间：
2014
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通讯作者：
J. L. Chávez
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作者：
Evan H. Rambikur;J. L. Chávez
参照 Timpas（美国科罗拉多州）附近相对平坦且均匀的草地上的涡流协方差 (EC) 系统，评估了三个 Kipp 和 Zonen 大孔径闪烁计 (LAS) 确定感热通量 (H) 的准确性。其他测试揭示了 Kipp 和 Zonen LAS 单位之间固有的变异性以及高估 H 的偏差。对 LAS 单位之间以及 LAS 和 EC 之间的平均 H 通量进行了比较。尽管相关性良好，但就线性回归斜率而言，H 中的 LAS 间偏差在 6% 到 13% 之间。据观察，物理未对准会导致对准良好和对准不良的 LAS 单元的 H 解之间的散射和偏差增加。 LAS 和 EC H 的比较显示，其中一个 LAS 单元几乎没有偏差，而其他两个单元高估了 EC H 超过 10%。探测器对准问题可能导致 LAS 之间的差异，本研究中对 LAS 单元之间不同功率要求的观察结果支持了这一点。 LAS 物理未对准可能会导致波束边缘信号噪声以及容易受到风致振动信号噪声的影响，两者都会对 H 的解产生影响。此外，LAS 和 EC 仪器的 H 解存在一些不确定性，包括缺乏与 EC 单元的能量平衡闭合。然而，所获得的结果并未显示出 Kipp 和 Zonen LAS 高估 H 的固有偏差的明确证据，如其他研究中发现的那样。
The accuracy in determining sensible heat flux (H) of three Kipp and Zonen large aperture scintillometers (LAS) was evaluated with reference to an eddy covariance (EC) system over relatively flat and uniform grassland near Timpas (CO, USA). Other tests have revealed inherent variability between Kipp and Zonen LAS units and bias to overestimate H. Average H fluxes were compared between LAS units and between LAS and EC. Despite good correlation, inter-LAS biases in H were found between 6% and 13% in terms of the linear regression slope. Physical misalignment was observed to result in increased scatter and bias between H solutions of a well-aligned and poorly-aligned LAS unit. Comparison of LAS and EC H showed little bias for one LAS unit, while the other two units overestimated EC H by more than 10%. A detector alignment issue may have caused the inter-LAS variability, supported by the observation in this study of differing power requirements between LAS units. It is possible that the LAS physical misalignment may have caused edge-of-beam signal noise as well as vulnerability to signal noise from wind-induced vibrations, both having an impact on the solution of H. In addition, there were some uncertainties in the solutions of H from the LAS and EC instruments, including lack of energy balance closure with the EC unit. However, the results obtained do not show clear evidence of inherent bias for the Kipp and Zonen LAS to overestimate H as found in other studies.