TY - JOUR

T1 - Comparison of conventional Lagrangian stochastic footprint models against les driven footprint estimates

AU - Markkanen, T.

AU - Steinfeld, G.

AU - Kljun, N.

AU - Raasch, S.

AU - Foken, T.

N1 - Funding Information: We thank German Science Foundation for funding of Tiina Markkanen and Gerald Steinfeld (projects FO 226/10-1,2 and RA 617/16-1,2). We also gratefully acknowl- edge the two anonymous reviewers for their constructive comments.

PY - 2009/8/6

Y1 - 2009/8/6

N2 - In this study we introduce a comparison method for footprint model results by evaluating 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 two unstably 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 more unstable case, whereas the two conventional flux footprint models agree best under less unstable conditions. The model comparison in 2-D was found quite sensitive to the grid resolution.

AB - In this study we introduce a comparison method for footprint model results by evaluating 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 two unstably 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 more unstable case, whereas the two conventional flux footprint models agree best under less unstable conditions. The model comparison in 2-D was found quite sensitive to the grid resolution.

UR - http://www.scopus.com/inward/record.url?scp=75249100217&partnerID=8YFLogxK

U2 - 10.5194/acp-9-5575-2009

DO - 10.5194/acp-9-5575-2009

M3 - Article

AN - SCOPUS:75249100217

VL - 9

SP - 5575

EP - 5586

JO - Atmospheric chemistry and physics

JF - Atmospheric chemistry and physics

SN - 1680-7316

IS - 15

ER -