Calibration of three-dimensional hot-film data using a collocated sonic anemometer

Abstract In this study, we evaluate hot-film data and test an in situ calibration method from simultaneous sonic anemometer measurements. The details of the calibration are provided, and its performance is validated by comparing results of spectra and structure functions with standard wind-tunnel data and model spectra. A single 3h block of data was selected, containing 33 subblocks of 2 min data without gaps, whose statistics were averaged to provide smooth results. This block was measured above canopy under stable conditions, and it corresponds to a Taylor Reynolds number Reλ ≈ 1550. The agreement with wind tunnel results for a similar Reλ and with model predictions provides a validation for the proposed in situ calibration method. Furthermore, the results indicate a presence of the bottleneck effect in the lateral and vertical spectra, in addition to a lack of inertial range in the second-order structure function due to the low Reynolds number.