Validation of conventional Lagrangian stochastic footprint models against LES driven footprint estimates
1Department of Micrometeorology, University of Bayreuth, 95440 Bayreuth, Germany
2Institut für Meteorologie und Klimatologie, Leibniz Universität Hannover, Hannover, Germany
3Department of Geography, Swansea University, Singleton Park, Swansea, Wales, UK
Abstract. In this study we compare the performance of conventional Lagrangian stochastic (LS) footprint models that use parameterised flow field characteristics with results of a Lagrangian trajectory model embedded in a large eddy simulation (LES) framework. The two conventional models follow the particles backward and forward in time while the trajectories in LES only evolve forward in time. We assess their performance in unstably and neutrally stratified boundary layers at observation levels covering the whole depth of the atmospheric boundary layer. We present a concept for footprint model comparison that can be applied for 2-D footprints and demonstrate that comparison of only cross wind integrated footprints is not sufficient for purposes facilitating two dimensional footprint information. Because the flow field description among the three models is most realistic in LES we use those results as the reference in the comparison. We found that the agreement of the two conventional models against the LES is generally better for intermediate measurement heights and for the convective case, whereas the two conventional flux footprint models agree best under near neutral conditions.