IngentaConnect A Simple Parameterisation for Flux Footprint Predictions

Authors: Kljun, N.¹; Calanca, P.; Rotach, M.; Schmid, H.

Source: Boundary-Layer Meteorology, Volume 112, Number 3, September 2004 , pp. 503-523(21)

Publisher: Springer

Abstract:

Flux footprint functions estimate the location and relative importance of passive scalar sources influencing flux measurements at a given receptor height. These footprint estimates strongly vary in size, depending on receptor height, atmospheric stability, and surface roughness. Reliable footprint calculations from, e.g., Lagrangian stochastic models or large-eddy simulations are computationally expensive and cannot readily be computed for long-term observational programs. To facilitate more accessible footprint estimates, a scaling procedure is introduced for flux footprint functions over a range of stratifications from convective to stable, and receptor heights ranging from near the surface to the middle of the boundary layer. It is shown that, when applying this scaling procedure, footprint estimates collapse to an ensemble of similar curves. A simple parameterisation for the scaled footprint estimates is presented. This parameterisation accounts for the influence of the roughness length on the footprint and allows for a quick but precise algebraic footprint estimation.

Keywords: Boundary-layer scaling; Boundary-layer stability; Fetch; Flux footprint; Lagrangian stochastic particle dispersion model; Parameterisation

Document Type: Research article

DOI: 10.1023/B:BOUN.0000030653.71031.96

Affiliations: 1: Email: nkljun@ethz.ch

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