A Refinement of the McMillen (1988) Recursive Digital Filter for the Analysis of Atmospheric Turbulence

We present a refinement of the recursive digital filter proposed by McMillen (Boundary-Layer Meteorol 43:231–245, 1988 ), for separating surface-layer turbulence from low-frequency fluctuations affecting the mean flow, especially over complex terrain. In fact, a straightforward application of the fi...

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Bibliographic Details
Published in:Boundary-layer meteorology 2018-09, Vol.168 (3), p.517-523
Main Authors: Falocchi, Marco, Giovannini, Lorenzo, Franceschi, Massimiliano de, Zardi, Dino
Format: Article
Language:English
Subjects:
Amplitude
Atmospheric Protection/Air Quality Control/Air Pollution
Atmospheric Sciences
Atmospheric turbulence
Attenuation
Boundary layer meteorology
Boundary layers
Digital filters
Earth and Environmental Science
Earth Sciences
Electronic filters
Fluctuations
Fluid dynamics
Mathematical models
Meteorology
Notes and Comments
Surface boundary layer
Turbulence (Fluid dynamics)
Turbulent fluctuations
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Summary:We present a refinement of the recursive digital filter proposed by McMillen (Boundary-Layer Meteorol 43:231–245, 1988 ), for separating surface-layer turbulence from low-frequency fluctuations affecting the mean flow, especially over complex terrain. In fact, a straightforward application of the filter causes both an amplitude attenuation and a forward phase shift in the filtered signal. As a consequence turbulence fluctuations, evaluated as the difference between the original series and the filtered one, as well as higher-order moments calculated from them, may be affected by serious inaccuracies. The new algorithm (i) produces a rigorous zero-phase filter, (ii) restores the amplitude of the low-frequency signal, and (iii) corrects all filter-induced signal distortions.
ISSN:0006-8314
1573-1472
DOI:10.1007/s10546-018-0355-5