Users manual for a branched Lagrangian transport model

Abstract. In this study, a hydrodynamic model was applied to the Nazaré submarine canyon with boundary forcing provided by an operational forecast model for the west Iberian coast for the spring of 2009. After validation, a lagrangian transport model was coupled to the hydrodynamic model to study and compare the transport patterns of three different classes of organo-mineral aggregates along the Nazaré canyon. The results show that the transport in the canyon is neither constant, nor unidirectional and that there are preferential areas where deposited matter is resuspended and redistributed. The transport of the larger class size of organo-mineral aggregates (2000 μm and 4000 μm) is less pronounced, and a decrease in the phytodetrital carbon flux along the canyon is observed. During the modelled period, the Nazaré canyon acts as a depocentre of sedimentary organic matter rather than a conduit of organo-mineral aggregates to the deep sea, as has been reported by other authors. The results of this study are crucial for the understanding of the oceanic carbon sequestration at the continental margin, and therefore important for evaluating the role of submarine canyons within the global carbon cycle.

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Massive-Parallel Trajectory Calculations version 2.2 (MPTRAC-2.2): Lagrangian transport simulations on Graphics Processing Units (GPUs)

10.5194/gmd-2021-382 ◽

2021 ◽

Author(s):

Lars Hoffmann ◽

Paul F. Baumeister ◽

Zhongyin Cai ◽

Jan Clemens ◽

Sabine Griessbach ◽

...

Keyword(s):

Graphics Processing Units ◽

Large Scale ◽

Transport Model ◽

Meteorological Data ◽

Transport Processes ◽

Model Verification ◽

Data Set ◽

Lagrangian Transport ◽

Trajectory Calculations ◽

Graphics Processing

Abstract. Lagrangian models are fundamental tools to study atmospheric transport processes and for practical applications such as dispersion modeling for anthropogenic and natural emission sources. However, conducting large-scale Lagrangian transport simulations with millions of air parcels or more can become numerically rather costly. In this study, we assessed the potential of exploiting graphics processing units (GPUs) to accelerate Lagrangian transport simulations. We ported the Massive-Parallel Trajectory Calculations (MPTRAC) model to GPUs using the open accelerator (OpenACC) programming model. The trajectory calculations conducted within the MPTRAC model were fully ported to GPUs, i.e., except for feeding in the meteorological input data and for extracting the particle output data, the code operates entirely on the GPU devices without frequent data transfers between CPU and GPU memory. Model verification, performance analyses, and scaling tests of the MPI/OpenMP/OpenACC hybrid parallelization of MPTRAC were conducted on the JUWELS Booster supercomputer operated by the Jülich Supercomputing Centre, Germany. The JUWELS Booster comprises 3744 NVIDIA A100 Tensor Core GPUs, providing a peak performance of 71.0 PFlop/s. As of June 2021, it is the most powerful supercomputer in Europe and listed among the most energy-efficient systems internationally. For large-scale simulations comprising 108 particles driven by the European Centre for Medium-Range Weather Forecasts' ERA5 reanalysis, the performance evaluation showed a maximum speedup of a factor of 16 due to the utilization of GPUs compared to CPU-only runs on the JUWELS Booster. In the large-scale GPU run, about 67 % of the runtime is spent on the physics calculations, conducted on the GPUs. Another 15 % of the runtime is required for file-I/O, mostly to read the large ERA5 data set from disk. Meteorological data preprocessing on the CPUs also requires about 15 % of the runtime. Although this study identified potential for further improvements of the GPU code, we consider the MPTRAC model ready for production runs on the JUWELS Booster in its present form. The GPU code provides a much faster time to solution than the CPU code, which is particularly relevant for near-real-time applications of a Lagrangian transport model.

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Massive-Parallel Trajectory Calculations version 2.2 (MPTRAC-2.2): Lagrangian transport simulations on Graphics Processing Units (GPUs)

10.31223/x52s7m ◽

2021 ◽

Author(s):

Lars Hoffmann ◽

Paul Baumeister ◽

Zhongyin Cai ◽

Jan Clemens ◽

Sabine Griessbach ◽

...

Keyword(s):

Graphics Processing Units ◽

Large Scale ◽

Transport Model ◽

Programming Model ◽

Meteorological Data ◽

Transport Processes ◽

Model Verification ◽

Lagrangian Transport ◽

Trajectory Calculations ◽

Graphics Processing

Lagrangian models are powerful tools to study atmospheric transport processes. However, conducting large-scaleLagrangian transport simulations with many air parcels can become numerically rather costly. In this study, we assessed the potential of exploiting graphics processing units (GPUs) to accelerate Lagrangian transport simulations. We ported the Massive-Parallel Trajectory Calculations (MPTRAC) model to GPUs using the open accelerator (OpenACC) programming model. The trajectory calculations conducted within the MPTRAC model have been fully ported to GPUs, i. e., except for feeding in the meteorological input data and for extracting the particle output data, the code operates entirely on the GPU devices without frequent data transfers between CPU and GPU memory. Model verification, performance analyses, and scaling tests of the MPI/OpenMP/OpenACC hybrid parallelization of MPTRAC have been conducted on the JUWELS Booster supercomputer operated by the Jülich Supercomputing Centre, Germany. The JUWELS Booster comprises 3744 NVIDIA A100 Tensor CoreGPUs, providing a peak performance of 71.0 PFlop/s. As of June 2021, it is the most powerful supercomputer in Europe and listed among the most energy-efficient systems internationally. For large-scale simulations comprising 100 million particles driven by the European Centre for Medium-Range Weather Forecasts’ ERA5 reanalysis, the performance evaluation showed a maximum speedup of a factor of 16 due to the utilization of GPUs compared to CPU-only runs on the JUWELS Booster. In the large-scale GPU run, about 67 % of the runtime is spent on the physics calculations, being conducted on the GPUs. Another 15 % of the runtime is required for file-I/O, mostly to read the ERA5 data from disk. Meteorological data preprocessing on the CPUs also requires about 15 % of the runtime. Although this study identified potential for further improvements of the GPU code, we consider the MPTRAC model to be ready for production runs on the JUWELS Booster in its present form. The GPU code provides a much faster time to solution than the CPU code, which is particularly relevant for near-real-time applications of a Lagrangian transport model

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Improved estimation of volcanic SO2 emissions from satellite observations and Lagrangian transport simulations: The 2019 Raikoke eruption case study

10.5194/egusphere-egu21-9111 ◽

2021 ◽

Author(s):

Zhongyin Cai ◽

Sabine Grießbach ◽

Lars Hoffmann

Keyword(s):

Emission Rate ◽

Transport Model ◽

Volcanic Eruptions ◽

Satellite Observations ◽

So2 Emissions ◽

So2 Emission ◽

Lagrangian Transport ◽

Trajectory Approach ◽

Volcanic Aerosols

<p>Monitoring and modeling of volcanic aerosols is important for understanding the influence of volcanic activity on climate. Here, we applied the Lagrangian transport model Massive-Parallel Trajectory Calculations (MPTRAC) to estimate the total injected SO2 by the stratosphere reaching eruption of the Raikoke volcano (48N, 153E) in June 2019 and its subsequent transport. We used SO2 observations from the AIRS and TROPOMI satellite instruments together with a backward trajectory approach to estimate the altitude-resolved SO2 emission timeseries. Then we applied a scaling factor to the initial estimate of the SO2 mass and added an exponential decay to simulate the time evolution of the total SO2 mass. By comparing the estimated SO2 mass and the observed mass from TROPOMI, we show that the volcano injected 2.1&#177;0.2 Tg SO2 and the e-folding lifetime of the SO2 was about 13~17 days. Further, we compared simulations that were initialized by AIRS and TROPOMI satellite observations with a constant SO2 emission rate. The results show that the model captures the SO2 distributions in the first ~10 days after the eruption. The simulations using AIRS nighttime and TROPOMI measurements show comparable results and model skills which outperform the simulation using a constant emission rate. Our study demonstrates the potential of using combined satellite observations and transport simulations to further improve SO2 time- and height-resolved emission estimates of volcanic eruptions.</p>

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Users manual for a one-dimensional Lagrangian transport model

10.3133/wri864145 ◽

1986 ◽

Keyword(s):

Transport Model ◽

Lagrangian Transport ◽

One Dimensional

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Calibration of a Lagrangian Transport Model Using Drifting Buoys Deployed during thePrestigeOil Spill

Journal of Coastal Research ◽

10.2112/07-0849.1 ◽

2009 ◽

Vol 251 ◽

pp. 80-90 ◽

Cited By ~ 51

Author(s):

Ana J. Abascal ◽

Sonia Castanedo ◽

Fernando J. Mendez ◽

Raul Medina ◽

Inigo J. Losada

Keyword(s):

Transport Model ◽

Lagrangian Transport ◽

Drifting Buoys

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COMET: a Lagrangian transport model for greenhouse gas emission estimation – forward model technique and performance for methane

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-6-8727-2006 ◽

2006 ◽

Vol 6 (5) ◽

pp. 8727-8779 ◽

Cited By ~ 21

Author(s):

A. T. Vermeulen ◽

G. Pieterse ◽

A. Hensen ◽

W. C. M. van den Bulk ◽

J. W. Erisman

Keyword(s):

Greenhouse Gas ◽

Greenhouse Gas Emission ◽

Transport Model ◽

Model Performance ◽

Model Parameters ◽

Atmospheric Concentration ◽

Absolute Size ◽

Lagrangian Transport ◽

Emission Estimation ◽

And Performance

Abstract. The Lagrangian transport model COMET has been developed to evaluate emission estimates based on atmospheric concentration observations. This paper describes the model and its application in modelling the methane concentrations at the European stations Cabauw and Macehead. The COMET model captures in most cases both synoptic and diurnal variations of the concentrations as a function of time and in absolute size quite well. The explained variability by COMET of the mixed layer concentration for Cabauw varies from 50% to 84%; for all hourly observations in 2002 the explained variability is 71% with a RMSE of 112 ppb. The explained variability for Macehead is 48%. The most important model parameters were tested for their influence on model performance, but in general the model is not very sensitive to variations within acceptable limits. For a regionally and locally polluted continental site the COMET model shows only a small bias and a moderate random error, and therefore is considered to capture the influence of the sources on the concentration variations quite well. It is therefore concluded that inverse methods and more specifically the COMET model is suitable to be applied in deriving independent estimates of greenhouse gas emissions using Source-Receptor relationships.

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Application of a Lagrangian transport model to organo-mineral aggregates within the Nazaré canyon

Biogeosciences Discussions ◽

10.5194/bgd-10-447-2013 ◽

2013 ◽

Vol 10 (1) ◽

pp. 447-481

Author(s):

S. Pando ◽

M. Juliano ◽

R. Garcia ◽

P. A. de Jesus Mendes ◽

L. Thomsen

Keyword(s):

Hydrodynamic Model ◽

Deep Sea ◽

Carbon Flux ◽

Transport Model ◽

Submarine Canyon ◽

Forecast Model ◽

The West ◽

Lagrangian Transport ◽

Transport Patterns ◽

Mineral Aggregates

Abstract. In this study, a hydrodynamic model was applied to the Nazaré submarine canyon with boundary forcing provided by an operational forecast model for the West Iberian coast. After validation, a Lagrangian transport model was coupled to the hydrodynamic model to study the transport patterns of the organo-mineral aggregates along the Nazaré canyon comparing three different classes of organo-mineral aggregates. The results showed that the transport in the canyon is neither constant, nor unidirectional and that there are preferential areas where suspended matter is resuspended, transported and deposited. The results showed that the transport of the larger size classes of organo-mineral aggregates is less pronounced, and that there is a decrease in the phytodetrital carbon flux along the canyon. The Nazaré canyon acts as depocenter of sedimentary organic matter and the canyon is not a conduit of organo-mineral aggregates to the deep sea.

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