Footprints in Homogeneously and Heterogeneously Driven Boundary Layers Derived from a Lagrangian Stochastic Particle Model Embedded into Large-Eddy Simulation |
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Authors: | Gerald Steinfeld Siegfried Raasch Tiina Markkanen |
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Institution: | 1. Institut für Meteorologie und Klimatologie, Leibniz Universit?t Hannover, Herrenh?user Str. 2, 30419, Hannover, Germany 2. Abteilung Mikrometeorologie, Universit?t Bayreuth, 95440, Bayreuth, Germany
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Abstract: | A Lagrangian stochastic (LS) model, which is embedded into a parallelised large-eddy simulation (LES) model, is used for dispersion
and footprint evaluations. For the first time an online coupling between LES and LS models is applied. The new model reproduces
concentration patterns, which were obtained in prior studies, provided that subgrid-scale turbulence is included in the LS
model. Comparisons with prior studies show that the model evaluates footprints successfully. Streamwise dispersion leads to
footprint maxima that are situated less far upstream than previously reported. Negative flux footprints are detected in the
convective boundary layer (CBL). The wide range of applicability of the model is shown by applying it under neutral and stable
stratification. It is pointed out that the turning of the wind direction with height leads to a considerable dependency of
source areas on height. First results of an application to a heterogeneously heated CBL are presented, which emphasize that
footprints are severely affected by the inhomogeneity. |
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Keywords: | Convective boundary layer Footprint Lagrangian stochastic model Large-eddy simulation Neutral boundary layer Stable boundary layer |
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