TY - JOUR

T1 - Comparison of large-eddy simulation data with spatially averaged measurements obtained by acoustic tomography

T2 - Presuppositions and first results

AU - Weinbrecht, Sonja

AU - Raasch, Siegfried

AU - Ziemann, Astrid

AU - Arnold, Klaus

AU - Raabe, Armin

N1 - Funding Information: We would like the thank Frank Beyrich and his colleagues of the Meteorological Observatory Lindenberg of the Deutscher Wetterdienst (German Meteorological Service) for hosting the field experiment and for providing the data from the operational measurement programme at the boundary-layer field site GM Falken-berg. Frank Beyrich, Frank Hohls and Marcus Letzel are acknowledged for comments on the manuscript. Two anonymous referees are also thanked for their constructive remarks. This research project was supported by the Deutsche Forschungsgemeinschaft under Grants RA 569/4-1,2 and RA 617/4-1,2. All runs were performed on SGI/Cray-T3E computers at the ZIB (i.e. the ‘Konrad Zuse Zentrum für Informationstechnik’ in Berlin) and at the Regionales Rechenzentrum für Niedersachsen (RRZN) in Hannover, Germany.

PY - 2004/6

Y1 - 2004/6

N2 - An attempt is made to compare results of large-eddy simulation (LES) in a convective boundary layer using the model PALM with experimental data obtained from acoustic travel time tomography. This method provides two-dimensional data arrays, which are considered as more suitable for LES-validation than classical local or line-integrated measurements, because the tomographic data are area- or volume-averaged. For a quantitative comparison with experimental data in general, some prerequisites have to be considered: First of all, the initial and boundary conditions of the LES model have to be provided correctly by the experiment. Considering measurement errors, a sensitivity study was performed to investigate the influence of inaccurate initial and boundary conditions on the simulation results. This showed that for determining some boundary conditions, such as the surface temperature and the roughness length, high measurement accuracies are necessary, which are difficult to reach or which at least require considerable extra measurement efforts. The initial and boundary conditions provided by the Lindenberg experiment in 1999 turned out to be of insufficient accuracy to allow quantitative comparisons. However, a qualitative comparison was performed instead to investigate if the acoustic tomography method is a proper method for comparisons with LES models in general. It showed a good qualitative agreement with some quantitative differences. These differences can partly be explained by the sensitivity of the LES to initial and boundary conditions and by the limitations of the acoustic tomography.

AB - An attempt is made to compare results of large-eddy simulation (LES) in a convective boundary layer using the model PALM with experimental data obtained from acoustic travel time tomography. This method provides two-dimensional data arrays, which are considered as more suitable for LES-validation than classical local or line-integrated measurements, because the tomographic data are area- or volume-averaged. For a quantitative comparison with experimental data in general, some prerequisites have to be considered: First of all, the initial and boundary conditions of the LES model have to be provided correctly by the experiment. Considering measurement errors, a sensitivity study was performed to investigate the influence of inaccurate initial and boundary conditions on the simulation results. This showed that for determining some boundary conditions, such as the surface temperature and the roughness length, high measurement accuracies are necessary, which are difficult to reach or which at least require considerable extra measurement efforts. The initial and boundary conditions provided by the Lindenberg experiment in 1999 turned out to be of insufficient accuracy to allow quantitative comparisons. However, a qualitative comparison was performed instead to investigate if the acoustic tomography method is a proper method for comparisons with LES models in general. It showed a good qualitative agreement with some quantitative differences. These differences can partly be explained by the sensitivity of the LES to initial and boundary conditions and by the limitations of the acoustic tomography.

KW - Acoustic tomography

KW - Boundary-layer observations

KW - Large-eddy simulation

KW - Sensitivity study

UR - http://www.scopus.com/inward/record.url?scp=1842684875&partnerID=8YFLogxK

U2 - 10.1023/B:BOUN.0000016501.92974.a5

DO - 10.1023/B:BOUN.0000016501.92974.a5

M3 - Article

AN - SCOPUS:1842684875

VL - 111

SP - 441

EP - 465

JO - Boundary-Layer Meteorology

JF - Boundary-Layer Meteorology

SN - 0006-8314

IS - 3

ER -