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Andreas Stohl - One of the best experts on this subject based on the ideXlab platform.
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source receptor matrix calculation for deposited mass with the lagrangian Particle Dispersion model flexpart v10 2 in backward mode
Geoscientific Model Development Discussions, 2017Co-Authors: Sabine Eckhardt, Massimo Cassiani, Nikolaos Evangeliou, Espen Sollum, Ignacio Pisso, Andreas StohlAbstract:Existing Lagrangian Particle Dispersion models are capable of establishing source-receptor relationships by running either forward or backward in time. For many applications, backward simulations can be computationally more efficient by several orders of magnitude. However, to date, the backward modelling capabilities have been limited to atmospheric concentrations or mixing ratios. In this paper, we extend the backward modelling technique to substances deposited at the Earth's surface by wet scavenging and dry deposition. This facilitates efficient calculation of emission sensitivities for deposition quantities, which opens new application fields such as the comprehensive analysis of measured deposition quantities, or of deposition recorded in snow samples or ice cores. This could also include inverse modelling of emission sources based on such measurements. We have tested the new scheme as implemented in the Lagrangian Particle Dispersion model FLEXPART v10.2 by comparing results from forward and backward calculations. We also present an example application for black carbon concentrations recorded in Arctic snow.
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the lagrangian Particle Dispersion model flexpart wrf version 3 1
Geoscientific Model Development, 2013Co-Authors: Massimo Cassiani, Andreas Stohl, Petra Seibert, J Brioude, Delia Arnold, D Morton, Wayne M AngevineAbstract:Abstract. The Lagrangian Particle Dispersion model FLEXPART was originally designed for calculating long-range and mesoscale Dispersion of air pollutants from point sources, such that occurring after an accident in a nuclear power plant. In the meantime, FLEXPART has evolved into a comprehensive tool for atmospheric transport modeling and analysis at different scales. A need for further multiscale modeling and analysis has encouraged new developments in FLEXPART. In this paper, we present a FLEXPART version that works with the Weather Research and Forecasting (WRF) mesoscale meteorological model. We explain how to run this new model and present special options and features that differ from those of the preceding versions. For instance, a novel turbulence scheme for the convective boundary layer has been included that considers both the skewness of turbulence in the vertical velocity as well as the vertical gradient in the air density. To our knowledge, FLEXPART is the first model for which such a scheme has been developed. On a more technical level, FLEXPART-WRF now offers effective parallelization, and details on computational performance are presented here. FLEXPART-WRF output can either be in binary or Network Common Data Form (NetCDF) format, both of which have efficient data compression. In addition, test case data and the source code are provided to the reader as a Supplement. This material and future developments will be accessible at http://www.flexpart.eu .
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east asian so 2 pollution plume over europe part 1 airborne trace gas measurements and source identification by Particle Dispersion model simulations
Atmospheric Chemistry and Physics, 2009Co-Authors: V Fiedler, Rainer Nau, S Ludmann, Frank Arnold, Hans Schlager, Andreas StohlAbstract:Abstract. A large SO2-rich pollution plume of East Asian origin was detected by aircraft based CIMS (Chemical Ionization Mass Spectrometry) measurements at 3–7.5 km altitude over the North Atlantic. The measurements, which took place on 3 May 2006 aboard of the German research aircraft Falcon, were part of the INTEX-B (Intercontinental Chemical Transport Experiment-B) campaign. Additional trace gases (NO, NOy, CO, H2O) were measured and used for comparison and source identification. The atmospheric SO2 mole fraction was markedly increased inside the plume and reached up to 900 pmol/mol. Accompanying lagrangian FLEXPART Particle Dispersion model simulations indicate that the probed pollution plume originated at low altitudes from densely populated and industrialized regions of East Asia, primarily China, about 8–12 days prior to the measurements.
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parameterization of convective transport in a lagrangian Particle Dispersion model and its evaluation
Journal of Applied Meteorology and Climatology, 2007Co-Authors: C Forster, Andreas Stohl, Petra SeibertAbstract:This paper presents the revision and evaluation of the interface between the convective parameterization by Emanuel and ivkovic ´-Rothman and the Lagrangian Particle Dispersion model “FLEXPART” based on meteorological data from the European Centre for Medium-Range Weather Forecasts (ECMWF). The convection scheme relies on the ECMWF grid-scale temperature and humidity and provides a matrix necessary for the vertical convective Particle displacement. The benefits of the revised interface relative to its previous version are presented. It is shown that, apart from minor fluctuations caused by the stochastic convective redistribution of the Particles, the well-mixed criterion is fulfilled in simulations that include convection. Although for technical reasons the calculation of the displacement matrix differs somewhat between the forward and the backward simulations in time, the mean relative difference between the convective mass fluxes in forward and backward simulations is below 3% and can therefore be tolerated. A comparison of the convective mass fluxes and precipitation rates with those archived in the 40-yr ECMWF Reanalysis (ERA-40) data reveals that the convection scheme in FLEXPART produces upward mass fluxes and precipitation rates that are generally smaller by about 25% than those from ERA-40. This result is interpreted as positive, because precipitation is known to be overestimated by the ECMWF model. Tracer transport simulations with and without convection are compared with surface and aircraft measurements from two tracer experiments and to 222 Rn measurements from two aircraft campaigns. At the surface no substantial differences between the model runs with and without convection are found, but at higher altitudes the model runs with convection produced better agreement with the measurements in most of the cases and indifferent results in the others. However, for the tracer experiments only few measurements at higher altitudes are available, and for the aircraft campaigns the 222 Rn emissions are highly uncertain. Other datasets better suitable for the validation of convective transport in models are not available. Thus, there is a clear need for reliable datasets suitable to validate vertical transport in models.
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technical note the lagrangian Particle Dispersion model flexpart version 6 2
Atmospheric Chemistry and Physics, 2005Co-Authors: Andreas Stohl, C Forster, A Frank, Petra Seibert, Gerhard WotawaAbstract:Abstract. The Lagrangian Particle Dispersion model FLEXPART was originally (about 8 years ago) designed for calculating the long-range and mesoscale Dispersion of air pollutants from point sources, such as after an accident in a nuclear power plant. In the meantime FLEXPART has evolved into a comprehensive tool for atmospheric transport modeling and analysis. Its application fields were extended from air pollution studies to other topics where atmospheric transport plays a role (e.g., exchange between the stratosphere and troposphere, or the global water cycle). It has evolved into a true community model that is now being used by at least 25 groups from 14 different countries and is seeing both operational and research applications. A user manual has been kept actual over the years and was distributed over an internet page along with the model's source code. In this note we provide a citeable technical description of FLEXPART's latest version (6.2).
Petra Seibert - One of the best experts on this subject based on the ideXlab platform.
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the lagrangian Particle Dispersion model flexpart wrf version 3 1
Geoscientific Model Development, 2013Co-Authors: Massimo Cassiani, Andreas Stohl, Petra Seibert, J Brioude, Delia Arnold, D Morton, Wayne M AngevineAbstract:Abstract. The Lagrangian Particle Dispersion model FLEXPART was originally designed for calculating long-range and mesoscale Dispersion of air pollutants from point sources, such that occurring after an accident in a nuclear power plant. In the meantime, FLEXPART has evolved into a comprehensive tool for atmospheric transport modeling and analysis at different scales. A need for further multiscale modeling and analysis has encouraged new developments in FLEXPART. In this paper, we present a FLEXPART version that works with the Weather Research and Forecasting (WRF) mesoscale meteorological model. We explain how to run this new model and present special options and features that differ from those of the preceding versions. For instance, a novel turbulence scheme for the convective boundary layer has been included that considers both the skewness of turbulence in the vertical velocity as well as the vertical gradient in the air density. To our knowledge, FLEXPART is the first model for which such a scheme has been developed. On a more technical level, FLEXPART-WRF now offers effective parallelization, and details on computational performance are presented here. FLEXPART-WRF output can either be in binary or Network Common Data Form (NetCDF) format, both of which have efficient data compression. In addition, test case data and the source code are provided to the reader as a Supplement. This material and future developments will be accessible at http://www.flexpart.eu .
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parameterization of convective transport in a lagrangian Particle Dispersion model and its evaluation
Journal of Applied Meteorology and Climatology, 2007Co-Authors: C Forster, Andreas Stohl, Petra SeibertAbstract:This paper presents the revision and evaluation of the interface between the convective parameterization by Emanuel and ivkovic ´-Rothman and the Lagrangian Particle Dispersion model “FLEXPART” based on meteorological data from the European Centre for Medium-Range Weather Forecasts (ECMWF). The convection scheme relies on the ECMWF grid-scale temperature and humidity and provides a matrix necessary for the vertical convective Particle displacement. The benefits of the revised interface relative to its previous version are presented. It is shown that, apart from minor fluctuations caused by the stochastic convective redistribution of the Particles, the well-mixed criterion is fulfilled in simulations that include convection. Although for technical reasons the calculation of the displacement matrix differs somewhat between the forward and the backward simulations in time, the mean relative difference between the convective mass fluxes in forward and backward simulations is below 3% and can therefore be tolerated. A comparison of the convective mass fluxes and precipitation rates with those archived in the 40-yr ECMWF Reanalysis (ERA-40) data reveals that the convection scheme in FLEXPART produces upward mass fluxes and precipitation rates that are generally smaller by about 25% than those from ERA-40. This result is interpreted as positive, because precipitation is known to be overestimated by the ECMWF model. Tracer transport simulations with and without convection are compared with surface and aircraft measurements from two tracer experiments and to 222 Rn measurements from two aircraft campaigns. At the surface no substantial differences between the model runs with and without convection are found, but at higher altitudes the model runs with convection produced better agreement with the measurements in most of the cases and indifferent results in the others. However, for the tracer experiments only few measurements at higher altitudes are available, and for the aircraft campaigns the 222 Rn emissions are highly uncertain. Other datasets better suitable for the validation of convective transport in models are not available. Thus, there is a clear need for reliable datasets suitable to validate vertical transport in models.
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technical note the lagrangian Particle Dispersion model flexpart version 6 2
Atmospheric Chemistry and Physics, 2005Co-Authors: Andreas Stohl, C Forster, A Frank, Petra Seibert, Gerhard WotawaAbstract:Abstract. The Lagrangian Particle Dispersion model FLEXPART was originally (about 8 years ago) designed for calculating the long-range and mesoscale Dispersion of air pollutants from point sources, such as after an accident in a nuclear power plant. In the meantime FLEXPART has evolved into a comprehensive tool for atmospheric transport modeling and analysis. Its application fields were extended from air pollution studies to other topics where atmospheric transport plays a role (e.g., exchange between the stratosphere and troposphere, or the global water cycle). It has evolved into a true community model that is now being used by at least 25 groups from 14 different countries and is seeing both operational and research applications. A user manual has been kept actual over the years and was distributed over an internet page along with the model's source code. In this note we provide a citeable technical description of FLEXPART's latest version (6.2).
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source receptor matrix calculation with a lagrangian Particle Dispersion model in backward mode
Atmospheric Chemistry and Physics, 2004Co-Authors: Petra Seibert, A FrankAbstract:Abstract. The possibility to calculate linear-source receptor relationships for the transport of atmospheric trace substances with a Lagrangian Particle Dispersion model (LPDM) running in backward mode is shown and presented with many tests and examples. This mode requires only minor modifications of the forward LPDM. The derivation includes the action of sources and of any first-order processes (transformation with prescribed rates, dry and wet deposition, radioactive decay, etc.). The backward mode is computationally advantageous if the number of receptors is less than the number of sources considered. The combination of an LPDM with the backward (adjoint) methodology is especially attractive for the application to point measurements, which can be handled without artificial numerical diffusion. Practical hints are provided for source-receptor calculations with different settings, both in forward and backward mode. The equivalence of forward and backward calculations is shown in simple tests for release and sampling of Particles, pure wet deposition, pure convective redistribution and realistic transport over a short distance. Furthermore, an application example explaining measurements of Cs-137 in Stockholm as transport from areas contaminated heavily in the Chernobyl disaster is included.
Md Shakhaoath Khan - One of the best experts on this subject based on the ideXlab platform.
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estimation of Dispersion coefficient in a solid liquid fluidised bed system
Powder Technology, 2020Co-Authors: Md Shakhaoath Khan, Ifsana Karim, Geoffrey Evans, Elham Doroodchi, J B Joshi, Subhasish MitraAbstract:Abstract Particle Dispersion behaviour in a solid liquid fluidised system leads to interesting outcomes such as mixing and segregation which are often quantified by an empirical Dispersion coefficient. The present study aims at providing a better estimation of Particle Dispersion behaviour from a fundamental definition analogous to diffusion coefficient. By tracking a tracer Particle using high speed image analysis, fluctuating velocity components (Vi/) were determined in a solid-liquid fluidised bed comprising glass Particles (dS = 8 mm, ρS = 2230 kg m−3) and water as a fluidising medium. Both inter-Particle and Particle-wall collisions were determined from the time varying jerk data. The Particle mean-free path (λ) was then estimated as a distance between two successive peaks in the jerk profile. Finally, Dispersion efficient D was computed based on the product of λ and V. Estimated Dispersion coefficients were compared with the available correlations and reasonable agreement was obtained.
J Brioude - One of the best experts on this subject based on the ideXlab platform.
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evaluation of lagrangian Particle Dispersion models with measurements from controlled tracer releases
Journal of Applied Meteorology and Climatology, 2013Co-Authors: J D Hegarty, Roland R Draxler, Ariel F Stein, J Brioude, M E Mountain, Janusz Eluszkiewicz, Thomas Nehrkorn, Fong NganAbstract:AbstractThree widely used Lagrangian Particle Dispersion models (LPDMs)—the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT), Stochastic Time-Inverted Lagrangian Transport (STILT), and Flexible Particle (FLEXPART) models—are evaluated with measurements from the controlled tracer-release experiments Cross-Appalachian Tracer Experiment (CAPTEX) and Across North America Tracer Experiment (ANATEX). The LPDMs are run forward in time driven by identical meteorological inputs from the North American Regional Reanalysis (NARR) and several configurations of the Weather Research and Forecasting (WRF) model, and the simulations of tracer concentrations are evaluated against the measurements with a ranking procedure derived from the combination of four statistical parameters. The statistical evaluation reveals that all three LPDMs have comparable skill in simulating the tracer plumes when driven by the same meteorological inputs, indicating that the differences in their formulations play a secondary ...
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the lagrangian Particle Dispersion model flexpart wrf version 3 1
Geoscientific Model Development, 2013Co-Authors: Massimo Cassiani, Andreas Stohl, Petra Seibert, J Brioude, Delia Arnold, D Morton, Wayne M AngevineAbstract:Abstract. The Lagrangian Particle Dispersion model FLEXPART was originally designed for calculating long-range and mesoscale Dispersion of air pollutants from point sources, such that occurring after an accident in a nuclear power plant. In the meantime, FLEXPART has evolved into a comprehensive tool for atmospheric transport modeling and analysis at different scales. A need for further multiscale modeling and analysis has encouraged new developments in FLEXPART. In this paper, we present a FLEXPART version that works with the Weather Research and Forecasting (WRF) mesoscale meteorological model. We explain how to run this new model and present special options and features that differ from those of the preceding versions. For instance, a novel turbulence scheme for the convective boundary layer has been included that considers both the skewness of turbulence in the vertical velocity as well as the vertical gradient in the air density. To our knowledge, FLEXPART is the first model for which such a scheme has been developed. On a more technical level, FLEXPART-WRF now offers effective parallelization, and details on computational performance are presented here. FLEXPART-WRF output can either be in binary or Network Common Data Form (NetCDF) format, both of which have efficient data compression. In addition, test case data and the source code are provided to the reader as a Supplement. This material and future developments will be accessible at http://www.flexpart.eu .
Wayne M Angevine - One of the best experts on this subject based on the ideXlab platform.
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the lagrangian Particle Dispersion model flexpart wrf version 3 1
Geoscientific Model Development, 2013Co-Authors: Massimo Cassiani, Andreas Stohl, Petra Seibert, J Brioude, Delia Arnold, D Morton, Wayne M AngevineAbstract:Abstract. The Lagrangian Particle Dispersion model FLEXPART was originally designed for calculating long-range and mesoscale Dispersion of air pollutants from point sources, such that occurring after an accident in a nuclear power plant. In the meantime, FLEXPART has evolved into a comprehensive tool for atmospheric transport modeling and analysis at different scales. A need for further multiscale modeling and analysis has encouraged new developments in FLEXPART. In this paper, we present a FLEXPART version that works with the Weather Research and Forecasting (WRF) mesoscale meteorological model. We explain how to run this new model and present special options and features that differ from those of the preceding versions. For instance, a novel turbulence scheme for the convective boundary layer has been included that considers both the skewness of turbulence in the vertical velocity as well as the vertical gradient in the air density. To our knowledge, FLEXPART is the first model for which such a scheme has been developed. On a more technical level, FLEXPART-WRF now offers effective parallelization, and details on computational performance are presented here. FLEXPART-WRF output can either be in binary or Network Common Data Form (NetCDF) format, both of which have efficient data compression. In addition, test case data and the source code are provided to the reader as a Supplement. This material and future developments will be accessible at http://www.flexpart.eu .