Two-wavelength scintillometer systems can provide much needed measurements of area-averaged sensible and latent heat fluxes. However, these devices rarely have been deployed on canopy-covered complex terrain, and never in the circumpolar boreal biome, where large-scale fluxes are essential to hydroclimate modellers. We present a comparison of fluxes measured above a boreal-forested valley with a two-wavelength scintillometer and an eddy covariance system. Instruments were deployed in late summer 2017, and 19 days of data were retained for the analysis. The scintillometer path was 1347-m long and projected across the valley between 5 and 100 m above the ground, with an effective height of $$\approx $$ ≈ 88 m. The limitations of deriving surface fluxes using scintillometry in complex terrain are discussed, and the effects of atmospheric conditions on the flux comparison are quantified. Fluxes are calculated with the scintillometer only, and using a number of atmospheric variables from the eddy-covariance system; impacts of these calculation methods on the correlation between instrumental systems are assessed. Despite a weak agreement of structure parameters between instruments, the comparison of scintillometer and eddy-covariance fluxes yields good correlation ( $$R^2$$ R 2 up to 0.82). Scintillometry correlates best with eddy-covariance data when the atmospheric surface-layer top is above the scintillometer effective height, but $$R^2$$ R 2 only drops slightly otherwise (average decrease of 0.11). The validity of scintillometer fluxes appears dubious during night-time and stable periods. We show that area-averaged flux measurements using two-wavelength scintillometers are possible in hilly forests, but more studies are needed to pinpoint the best methodological framework.

中文翻译：

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一种双波长闪烁测量系统在复杂的浅层北方森林山谷中的应用和评价

双波长闪烁仪系统可以提供非常需要的面积平均感热和潜热通量的测量。然而，这些设备很少部署在冠层覆盖的复杂地形上，也从未部署在环北极生物群落中，在那里大规模通量对水文气候建模者至关重要。我们用双波长闪烁仪和涡流协方差系统对在北方森林山谷上方测量的通量进行了比较。仪器于 2017 年夏末部署，并保留了 19 天的数据用于分析。闪烁计路径长 1347 米，投射在距地面 5 到 100 m 的山谷中，有效高度为 $$\approx $$ ≈ 88 m。讨论了在复杂地形中使用闪烁测量法推导表面通量的局限性，并且量化了大气条件对通量比较的影响。仅使用闪烁仪计算通量，并使用涡流协方差系统中的许多大气变量；评估了这些计算方法对仪器系统之间相关性的影响。尽管仪器之间结构参数的一致性较弱，但闪烁仪和涡流协方差通量的比较产生了良好的相关性（$$R^2$$R 2 高达 0.82）。当大气表层顶部高于闪烁仪有效高度时，闪烁测量法与涡旋协方差数据的相关性最好，但 $$R^2$$R 2 仅略有下降（平均下降 0.11）。在夜间和稳定时期，闪烁仪通量的有效性似乎令人怀疑。