Eddy-covariance flux measurements with a weight-shift microlightaircraft

[摘要] The objective of this study is to assess the feasibility and qualityof eddy-covariance flux measurements from a weight-shift microlightaircraft (WSMA). Firstly, we investigate the precision of the windmeasurement (σ_u,v ≤ 0.09 m s⁻¹,σ_w = 0.04 m s⁻¹), the lynchpin offlux calculations from aircraft. From here, the smallest resolvablechanges in friction velocity (0.02 m s⁻¹), and sensible-(5 W m⁻²) and latent (3 W m⁻²) heat flux areestimated. Secondly, a seven-day flight campaign was performed nearLindenberg (Germany). Here we compare measurements of wind,temperature, humidity and respective fluxes between a tall tower andthe WSMA. The maximum likelihood functional relationship (MLFR)between tower and WSMA measurements considers the random error inthe data, and shows very good agreement of the scalar averages. TheMLFRs for standard deviations (SDs, 2–34%) and fluxes(17–21%) indicate higher estimates of the airbornemeasurements compared to the tower. Considering the 99.5%confidence intervals, the observed differences are not significant,with exception of the temperature SD. The comparison witha large-aperture scintillometer reveals lower sensible heat fluxestimates at both tower (−40 to −25%) and WSMA(−25–0%). We relate the observed differences to (i) inconsistencies in the temperature and wind measurement at the towerand (ii) the measurement platforms' differing abilities to capturecontributions from non-propagating eddies. These findings encouragethe use of WSMA as a low cost and highly versatile flux measurementplatform.

[学科分类] 几何与拓扑