A Three-Dimensional Backward Lagrangian Footprint Model For A Wide Range Of Boundary-Layer Stratifications
Authors: Kljun N.1; Rotach M.W.2; Schmid H.P.3
Source: Boundary-Layer Meteorology, Volume 103, Number 2, May 2002 , pp. 205-226(22)
Publisher: Springer
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Abstract:
We present a three-dimensional Lagrangian footprint model with the ability to predict the area of influence (footprint) of a measurement within a wide range of boundary-layer stratifications and receptor heights. The model approach uses stochastic backward trajectories of particles and satisfies the well-mixed condition in inhomogeneous turbulence for continuous transitions from stable to convective stratification. We introduce a spin-up procedure of the model and a statistical treatment of particle touchdowns which leads to a significant reduction of CPU time compared to conventional footprint modelling approaches. A comparison with other footprint models (of the analytical and Lagrangian type) suggests that the present backward Lagrangian model provides valid footprint predictions under any stratification and, moreover, for applications that reach across different similarity scaling domains (e.g., surface layer to mixed layer, for use in connection with aircraft measurements or with observations on high towers).
Keywords: Backward trajectories; Boundary-layer stability; Density kernel estimation; Lagrangian particle model; Source area; Spin-up
Language: English
Document Type: Regular paper
Affiliations: 1: Institute for Atmospheric and Climate Science ETH, Zurich, Switzerland E-mail: nkljun@ethz.ch 2: Institute for Atmospheric and Climate Science ETH, Zurich, Switzerland 3: Department of Geography, Indiana University, Bloomington, Indiana, U.S.A.
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