Recent research indicates that non-orthogonal sonic anemometers underestimate vertical wind velocity and consequently eddy-covariance fluxes of mass and energy. Whether this is a general problem among all non-orthogonal sonic anemometers, including those calibrated for flow-shadowing effects, is unknown. To investigate this, we test two sonic anemometer designs, orthogonal (3Vx-probe, Applied Technologies, Inc.) and non-orthogonal (R3-50, Gill Instruments, Ltd.), in a series of field manipulation experiments featuring replicate instruments mounted in various orientations, and use a Bayesian analysis to determine the most likely posterior correction to produce equivalent measurements. The 3Vx-probe experiment was conducted on a 24-m scaffold at the Glacier Lakes Ecosystem Experiments Site (GLEES), Wyoming, USA AmeriFlux site while R3-50 anemometer experiments were conducted at the GLEES field site and on a 2.9-m scaffold at the Pawnee National Grassland, Colorado, USA. Without applying a shadowing correction to the 3Vx-probe, the posterior correction significantly increases the standard deviation of the horizontal velocity component by 5–15% (95% Bayesian credible interval) but without a significant change in the horizontal temperature flux; with the shadowing correction applied neither of these have significant changes. Similarly, for the R3-50 GLEES experiment, the standard deviation of the vertical velocity and vertical temperature flux significantly increase by 13–18% and 6–10% (95% credible intervals); results from the Pawnee experiment are contradictory and inconclusive. The reason for the underestimated vertical velocity is undetermined, though a mathematical by-product of the non-orthogonal geometry is that small systematic measurement biases can become large uncertainties in the vertical velocity. This could affect all non-orthogonal designs.

中文翻译：

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坐标旋转-非正交声速风速计垂直风速不确定度和偏差的放大

最近的研究表明，非正交声波风速计低估了垂直风速，从而低估了质量和能量的涡流协方差通量。这是否是所有非正交声波风速计（包括针对流动阴影效应校准的那些）中的普遍问题尚不清楚。为了研究这一点，我们在一系列现场操作实验中测试了两种声波风速计设计，正交（3Vx-probe，Applied Technologies, Inc.）和非正交（R3-50，Gill Instruments, Ltd.），其中安装了重复仪器在各种方向上，并使用贝叶斯分析来确定最可能的后验校正以产生等效的测量值。3Vx 探针实验是在怀俄明州冰川湖生态系统实验场 (GLEES) 的 24 米支架上进行的，美国 AmeriFlux 站点，而 R3-50 风速计实验在 GLEES 现场站点和美国科罗拉多州波尼国家草原的 2.9 米支架上进行。在不对 3Vx 探针应用阴影校正的情况下，后验校正显着增加了水平速度分量的标准偏差 5-15%（95% 贝叶斯可信区间），但水平温度通量没有显着变化；应用阴影校正后，这些都没有显着变化。同样，对于 R3-50 GLEES 实验，垂直速度和垂直温度通量的标准偏差显着增加了 13-18% 和 6-10%（95% 可信区间）；Pawnee 实验的结果是矛盾和不确定的。垂直速度被低估的原因尚未确定，尽管非正交几何的数学副产品是小的系统测量偏差可能成为垂直速度的大不确定性。这可能会影响所有非正交设计。