TY - GEN A1 - Becker, Andreas A1 - Schaller, Eberhard A1 - Keuler, Klaus T1 - Continuous four-dimensional source attribution for the Berlin area during two days in July 1994. Part II: Sensitivy studies N2 - The multiple nested three-dimensional (3D) mesoscale Eulerian grid point model MM5 is directly coupled with a Lagrangian particle trajectory model in order to perform a four-dimensional source attribution for the area of Berlin based on the horizontal distribution of the import probability density (IPD). KW - LaMM5 KW - Source-receptor relationship KW - Euler-Lagrange model system KW - vertical mixing KW - FluMOB experiment Y1 - 2001 ER - TY - CHAP A1 - Seelig, Torsten A1 - Harlander, Uwe A1 - Borcia, Ion-Dan A1 - Scurtu, Nicoleta A1 - Egbers, Christoph A1 - Klein, Marten A1 - Ghasemi, Abouzar A1 - Will, Andreas A1 - Schaller, Eberhard T1 - Inertial waves in rotating cylindrical annulus: theory, experiment and simulations T2 - Book of abstracts, 9th European Fluid Mechanics Conference (EFMC), 9-13 September, Rome, Italy Y1 - 2012 UR - http://www.efmc9.eu/absbook/index.html ER - TY - CHAP A1 - Seelig, Torsten A1 - Borcia, Ion-Dan A1 - Klein, Marten A1 - Ghasemi, Abouzar A1 - Will, Andreas A1 - Egbers, Christoph A1 - Schaller, Eberhard A1 - Harlander, Uwe T1 - Inertial waves and wave attractors in a rotating annulus with inner or outer cylinder libration T2 - European Geosciences Union (EGU), 10th General Assembly, Vienna, Austria, 07 – 12 April 2013 Y1 - 2013 UR - http://meetingorganizer.copernicus.org/EGU2013/EGU2013-7602.pdf N1 - EGU2013-7602 ER - TY - GEN A1 - Klein, Marten A1 - Seelig, Torsten A1 - Kurgansky, Michael V. A1 - Ghasemi, Abouzar A1 - Borcia, Ion-Dan A1 - Will, Andreas A1 - Schaller, Eberhard A1 - Egbers, Christoph A1 - Harlander, Uwe T1 - Inertial wave excitation and focusing in a liquid bounded by a frustum and a cylinder T2 - Journal of Fluid Mechanics N2 - The mechanism of localized inertial wave excitation and its efficiency is investigated for an annular cavity rotating with Ω0 . Meridional symmetry is broken by replacing the inner cylinder with a truncated cone (frustum). Waves are excited by individual longitudinal libration of the walls. The geometry is non-separable and exhibits wave focusing and wave attractors. We investigated laboratory and numerical results for the Ekman number E ≈ 10−6. inclination α = 5.71◦ and libration amplitudes ε 0.2 within the inertial wave band 0 < ω < 2Ω0 . Under the assumption that the inertial waves do not essentially affect the boundary-layer structure, we use classical boundary-layer analysis to study oscillating Ekman layers over a librating wall that is at an angle α = 0 to the axis of rotation. The Ekman layer erupts at frequency ω = f∗, where f∗ ≡ 2Ω0 sin α is the effective Coriolis parameter in a plane tangential to the wall. For the selected inclination this eruption occurs for the forcing frequency ω/Ω0 = 0.2. For the librating lids eruption occurs at ω/Ω0 = 2. The study reveals that the frequency dependence of the total kinetic energy Kω of the excited wave field is strongly connected to the square of the Ekman pumping velocity wE (ω) that, in the linear limit, becomes singular when the boundary layer erupts. This explains the frequency dependence of non-resonantly excited waves. By the localization of the forcing, the two configurations investigated, (i) frustum libration and (ii) lids together with outer cylinder in libration, can be clearly distinguished by their response spectra. Good agreement was found for the spatial structure of low-order wave attractors and periodic orbits (both characterized by a small number of reflections) in the frequency windows predicted by geometric ray tracing. For ‘resonant’ frequencies a significantly increased total bulk energy was found, while the energy in the boundary layer remained nearly constant. Inertial wave energy enters the bulk flow via corner beams, which are parallel to the characteristics of the underlying Poincaré problem. Numerical simulations revealed a mismatch between the wall-parallel mass fluxes near the corners. This leads to boundary-layer eruption and the generation of inertial waves in the corners. KW - boundary-layer structure KW - geophysical and geological flows KW - waves in rotating fluids Y1 - 2014 U6 - https://doi.org/10.1017/jfm.2014.304 SN - 1750-6859 IS - vol. 751 SP - 255 EP - 297 ER - TY - CHAP A1 - Schaller, Eberhard ED - Hüttl, Reinhard F. ED - Emmermann, Rolf ED - Germer, Sonja ED - Naumann, Matthias ED - Bens, Oliver T1 - Simulation des gegenwärtigen und zukünftigen Regionalklimas von Brandenburg T2 - Globaler Wandel und regionale Entwicklung Y1 - 2011 U6 - https://doi.org/10.1007/978-3-642-19478-8 SP - 37 EP - 142 PB - Springer CY - Berlin [u.a.] ER - TY - CHAP A1 - An, Ni A1 - Schaller, Eberhard ED - Schmitz-Hoffmann, Carsten ED - Schmidt, Michael ED - Hansmann, Berthold ED - Palekhov, Dmitry T1 - Issues and Opportunities for Implementation of VSS in China T2 - Voluntary Standard Systems Y1 - 2014 SN - 978-3-642-35715-2 SN - 978-3-642-35716-9 U6 - https://doi.org/10.1007/978-3-642-35716-9 SP - 243 EP - 251 PB - Springer CY - Berlin [u.a.] ER - TY - CHAP A1 - Keuler, Klaus A1 - Block, Alexander A1 - Schaller, Eberhard ED - Bärring, Lars ED - Laprise, Rene T1 - Assessment of quality and uncertainty in regional climate simulations T2 - Extended abstracts of a WMO/WCRP-sponsored Regional-Scale Climate Modelling Workshop, high-resolution climate modelling, assessment, added value and applications, Lund, Sweden, 29 March-2 April 2004 Y1 - 2005 SP - 68 EP - 69 PB - Lund University CY - Lund, Sweden ER - TY - CHAP A1 - Keuler, Klaus A1 - Radtke, Kai S. A1 - Schaller, Eberhard ED - Rockel, Burkhardt ED - Bärring, Lars ED - Reckermann, Marcus T1 - Effect of internal variability on regional climate change projections T2 - 2nd International Lund RCM Workshop : 21st Century Challenges in Regional-scale Climate Modelling, Lund University, Sweden, 4-8 May 2008, workshop proceedings Y1 - 2009 SP - 132 EP - 133 PB - International BALTEX Secretariat CY - GKSS Forschungszentrum Geesthacht ER - TY - CHAP A1 - Klein, Marten A1 - Borcia, Ion-Dan A1 - Egbers, Christoph A1 - Ghasemi, Abouzar A1 - Harlander, Uwe A1 - Kurgansky, Michael V. A1 - Schaller, Eberhard A1 - Seelig, Torsten A1 - Will, Andreas T1 - Inertial Waves and Wave Excitation Mechanisms in Annular Cavities: Simulations, Experiments and Theory T2 - European Turbulence Conference ETC14, Lyon, 2013 KW - boundary-layer structure KW - geophysical and geological flows KW - waves in rotating fluids Y1 - 2013 UR - http://etc14.ens-lyon.fr/etc-14-proceedings/accepted-talks ER - TY - CHAP A1 - Brück, Yasemine A1 - Pohle, Ina A1 - Keuler, Klaus A1 - Schaller, Eberhard A1 - Hinz, Christoph T1 - Do mining lakes in the Lusatian Lignite mining region (Eastern Germany) affect regional precipitation patterns? T2 - European Geosciences Union, General Assembly 2016, Vienna, Austria N2 - Due to the flooding of former open-pit mines, Europe’s largest artificial lake district is created in Eastern Germany. Between 1990 and 2006 more than 80 km² of new lakes have already been formed. These large-scale land cover changes may impact regional meteorological characteristics, therefore it is of interest, whether effects of the mining lakes can already be observed. We especially focus on whether the evaporation from the mining pit lakes leads to a higher precipitation on their lee side. To detect changes in the precipitation patterns, we analysed daily precipitation data (1980-2014) of 25 stations in an area of 10 000 km² widely around the lake district. Under the assumption that the influences of the lakes should be detectable either directly as trends in the observed data or as a deviation from a general measure for precipitation we combined statistical tests and principal component analysis (PCA). We applied pre-whitening Mann-Kendall tests to detect precipitation trends and Mann-Whitney tests to detect differences between split samples (before and after the flooding of most of the lakes). The PCA was applied based on the correlation matrix of daily precipitation at the different stations. As the daily precipitation can sufficiently be explained by the first five principal components, the recombination of these five principal components was used as a general measure of precipitation in the region. By regression trees (random forests) a relation between the eigenvectors of the first five principal components and physiogeographic characteristics of the stations (e.g. altitude) was shown. Both the observed data and the deviations between the measurements and the recombination of the first five principal components showed divergent trends with high spatial variability and also interannual variability, but a pattern consistent with the lee side of the lake could not be detected. Therefore, it has been demonstrated that the emerging lakes had no influence on the daily precipitation at the stations considered in this study. This may be explained by the coarse spatial and also temporal resolution of precipitation measurements. Still, the approach presented here can be applied to (i) detect changes in the spatial pattern of climate variables by a combination of statistical tests and PCA and (ii) to analyse the relationships between such changes and physiogeographic characteristics by regression trees. Y1 - 2016 UR - http://meetingorganizer.copernicus.org/EGU2016/EGU2016-7663.pdf N1 - EGU2016-7663 PB - European Geophysical Society CY - Katlenburg-Lindau ER - TY - GEN A1 - Ghasemi, Abouzar A1 - Klein, Marten A1 - Harlander, Uwe A1 - Kurgansky, Michael V. A1 - Schaller, Eberhard A1 - Will, Andreas T1 - Mean flow generation by Görtler vortices in a rotating annulus with librating side walls T2 - Physics of Fluids N2 - Time periodic variation of the rotation rate of an annulus induces in supercritical regime an unstable Stokes boundary layer over the cylinder side walls, generating Görtler vortices in a portion of a libration cycle as a discrete event. Numerical results show that these vortices propagate into the fluid bulk and generate an azimuthal mean flow. Direct numerical simulations of the fluid flow in an annular container with librating outer (inner) cylinder side wall and Reynolds-averaged Navier–Stokes (RANS) equations as diagnostic equations are used to investigate generation mechanism of the retrograde (prograde) azimuthal mean flow in the bulk. First, we explain, phenomenologically, how absolute angular momentum of the bulk flow is mixed and changed due to the propagation of the Görtler vortices, causing a new vortex of basin size. Then we investigate the RANS equations for intermediate time scale of the development of the Görtler vortices and for long time scale of the order of several libration periods. The former exhibits sign selection of the azimuthal mean flow. Investigating the latter, we predict that the azimuthal mean flow is proportional to the libration amplitude squared and to the inverse square root of the Ekman number and libration frequency and then confirms this using the numerical data. Additionally, presence of an upscale cascade of energy is shown, using the kinetic energy budget of fluctuating flow. KW - Direct Numerical Simulation KW - Fluid Mechanics KW - Mean Flow KW - Rotation KW - Cylinder KW - Centrifugal KW - Instability KW - Mechanism KW - Vortex Y1 - 2016 U6 - https://doi.org/10.1063/1.4948406 VL - 28 IS - 056603 SP - 1 EP - 23 ER - TY - GEN A1 - Block, Alexander A1 - Keuler, Klaus A1 - Schaller, Eberhard T1 - Impacts of anthropogenic heat on regional climate patterns T2 - Geophysical Research Letters N2 - [1] Four different simulations of a winter period in Central Europe are carried out to investigate the principle effect of anthropogenic heat release from the highly industrialized and populated Ruhrarea region (Germany) on regional climate conditions. The results reveal a permanent warming due to anthropogenic heat emissions over affected areas ranging from 0.15 K over land area with an additional 2 W m−2 anthropogenic heat flux up to 0.5 K over the Ruhrarea with additional 20 W m−2 anthropogenic heat flux. The temperature effects induced by anthropogenic heat not only depend on the amount of added heat but also on orographical factors. No significant variations are found for precipitation. Y1 - 2004 U6 - https://doi.org/10.1029/2004GL019852 VL - 31 IS - 12 ER - TY - CHAP A1 - Tsonkova, Penka A1 - Freese, Dirk A1 - Böhm, Christian A1 - Quinkenstein, Ansgar A1 - Schaller, Eberhard ED - Freese, Dirk ED - Pittruff, N. ED - Quinkenstein, Ansgar ED - Böhm, Christian T1 - Benefits provided by silvoarable agroforestry systems in the temperate region: a review T2 - Proceedings of the International Workshop on Agroforestry - Ecological Benefits of Agroforestry, 15-17 June 2011, Cottbus, Germany Y1 - 2011 UR - http://www-docs.tu-cottbus.de/multiland/public/FreeseEtAl2011_Proceedings_of_the_International_Workshop_on_Agroforestry.pdf SP - S. 29 ER - TY - GEN A1 - Tsonkova, Penka A1 - Quinkenstein, Ansgar A1 - Böhm, Christian A1 - Freese, Dirk A1 - Schaller, Eberhard T1 - Ecosystem services assessment tool for agroforestry (ESAT-A): Anapproach to assess selected ecosystem services provided by alleycropping systems T2 - Ecological Indicators Y1 - 2014 U6 - https://doi.org/10.1016/j.ecolind.2014.04.024 IS - 45 SP - 285 EP - 299 ER -