Simulation of primary and secondary particles in the streets of Paris using MUNICH

2021 ◽  
Author(s):  
Lya Lugon ◽  
Karine Sartelet ◽  
Youngseob Kim ◽  
Jéremy Vigneron ◽  
Olivier Chrétien
Keyword(s):  
Local Scale ◽  
Sensitivity Test ◽  
Scale Model ◽  
Secondary Species ◽  
Secondary Particles ◽  
Secondary Aerosols

This study presents the new version of the local-scale model MUNICH, capable to represent the formation of secondary species in gas and particulate phases. A sensitivity test is performed to investigate the formation of secondary aerosols in streets.

scholarly journals A Bootstrap Technique for Testing the Relationship between Local-Scale Radar Observations of Cloud Occurrence and Large-Scale Atmospheric Fields

2006 ◽  
Vol 63 (11) ◽  
pp. 2813-2830 ◽  
Author(s):  
Roger Marchand ◽  
Nathaniel Beagley ◽  
Sandra E. Thompson ◽  
Thomas P. Ackerman ◽  
David M. Schultz
Keyword(s):  
Large Scale ◽  
Climate Models ◽  
Initial Conditions ◽  
Global Climate ◽  
Stable State ◽  
Local Scale ◽  
Global Climate Models ◽  
Scale Model ◽  
Synoptic Scale ◽  
Cloud Properties

Abstract A classification scheme is created to map the synoptic-scale (large scale) atmospheric state to distributions of local-scale cloud properties. This mapping is accomplished by a neural network that classifies 17 months of synoptic-scale initial conditions from the rapid update cycle forecast model into 25 different states. The corresponding data from a vertically pointing millimeter-wavelength cloud radar (from the Atmospheric Radiation Measurement Program Southern Great Plains site at Lamont, Oklahoma) are sorted into these 25 states, producing vertical profiles of cloud occurrence. The temporal stability and distinctiveness of these 25 profiles are analyzed using a bootstrap resampling technique. A stable-state-based mapping from synoptic-scale model fields to local-scale cloud properties could be useful in three ways. First, such a mapping may improve the understanding of differences in cloud properties between output from global climate models and observations by providing a physical context. Second, this mapping could be used to identify the cause of errors in the modeled distribution of clouds—whether the cause is a difference in state occurrence (the type of synoptic activity) or the misrepresentation of clouds for a particular state. Third, robust mappings could form the basis of a new statistical cloud parameterization.

Hydrodynamic Analysis of Macroalgae Local Model Using Computational Fluid Dynamics

2020 ◽  
Author(s):  
Ming Chen ◽  
Solomon C. Yim ◽  
Daniel Cox ◽  
Zhaoqing Yang ◽  
Thomas Mumford
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Current Model ◽  
Global Scale ◽  
Local Scale ◽  
Constant Current ◽  
Scale Model ◽  
Effective Diameter ◽  
Hydrodynamic Coefficients

Abstract In this article, a local scale, fully nonlinear coupled fluid-structural interaction (FSI) sugar kelp model has been developed using a computational fluid dynamics (CFD) method. In this model, to be consistent with available experimental data, the sugar kelp is approximated as elongated rectangles with smoothed isosceles triangles at the ends and a single kelp model with one end fixed in a channel with constant current model is developed. Several different current speeds are simulated, and the resulting drag forces and calculated drag coefficients are validated by comparison with experimental data from the literature. In a previous study, a global scale model was developed using a computational structural dynamics (CSD) method to simulate macroalgae farming system and guide the system configuration design. In the global scale model, the hydrodynamic forces are calculated using Morison’s equation and the kinematics and dynamics of the sugar kelp are simplified and the group of kelps attached to the long line is modeled as a slender structure with the same length and an effective diameter such that the volumes are consistent with the real physical system. This simplified model matches the weight and buoyancy but adjusting the hydrodynamic properties when the general hydrodynamic coefficients are employed. Therefore, optimal hydrodynamic coefficients used in global scale model were determined to obtain the hydrodynamic force more accurately. The validated local scale model is then be applied to determine the hydrodynamic coefficients of the simplified sugar kelp model for global dynamic analysis.

scholarly journals A Stochastic Two-Scale Model for Rarefied Gas Flow in Highly Heterogeneous Porous Media

2020 ◽  
Vol 135 (1) ◽  
pp. 219-242
Author(s):  
Francesc Pérez-Ràfols ◽  
Fredrik Forsberg ◽  
Gunnar Hellström ◽  
Andreas Almqvist
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Gas Flow ◽  
Present Model ◽  
Rarefied Gas ◽  
Slip Flow ◽  
Local Scale ◽  
Heterogeneous Porous Media ◽  
Scale Model ◽  
Rarefied Gas Flow

Abstract This paper presents the development of a model enabling the analysis of rarefied gas flow through highly heterogeneous porous media. To capture the characteristics associated with the global- and the local-scale topology of the permeable phase in a typical porous medium, the heterogeneous multi-scale method, which is a flexible framework for constructing two-scale models, was employed. The rapid spatial variations associated with the local-scale topology are accounted for stochastically, by treating the permeability of different local-scale domains as a random variable. The results obtained with the present model show that an increase in the spatial variability in the heterogeneous topology of the porous medium significantly reduces the relevance of rarefaction effects. This clearly shows the necessity of considering a realistic description of the pore topology and questions the applicability of the results obtained for topologies exhibiting regular pore patterns. Although the present model is developed to study low Knudsen number flows, i.e. the slip-flow regime, the same development procedure could be readily adapted for other regimes as well.

A Multi-Scale Scheme for Modelling Fracture under Dynamic Loading Conditions

2014 ◽  
Vol 627 ◽  
pp. 37-40
Author(s):  
A. Karamnejad ◽  
L.J. Sluys
Keyword(s):  
Dynamic Loading ◽  
Static Problem ◽  
Global Scale ◽  
Local Scale ◽  
Material Point ◽  
Computational Homogenization ◽  
Scale Model ◽  
Multi Scale ◽  
Damaged Zone ◽  
Scale Scheme

Fracture in heterogeneous materials under dynamic loading is modelled using a multi-scale method. Computational homogenization is considered, in which the overall properties at the global-scale are obtained by solving a boundary value problem for a representative volume element (RVE) assigned to each material point of the global-scale model. In order to overcome the problems with upscaling of localized deformations, a non-standard failure zone averaging scheme is used. Discontinuous cohesive macro-cracking is modelled using the XFEM and a gradient-enhanced damage model is used to model diffuse damage at the local-scale. A continuous-discontinuous computational homogenization method is employed to obtain the traction-separation law for macro-cracks using averaged properties calculated over the damaged zone in the RVE. In the multi-scale model, a dynamic analysis is performed for the global-scale model and the local-scale model is solved as a quasi-static problem. Dispersion effects are then captured by accounting for the inertia forces at the local-scale model via a so-called dispersion tensor which depends on the heterogeneity of the RVE. Numerical examples are presented and the multi-scale model results are compared to direct numerical simulation results. Objectivity of the multi-scale scheme with respect to the RVE size is examined.

scholarly journals Tree canopy and snow depth relationships at fine scales with terrestrial laser scanning

2020 ◽  
Author(s):  
Ahmad Hojatimalekshah ◽  
Zach Uhlmann ◽  
Nancy F. Glenn ◽  
Christopher A. Hiemstra ◽  
Christopher J. Tennant ◽  
...  
Keyword(s):  
Snow Depth ◽  
Laser Scanning ◽  
Terrestrial Laser Scanning ◽  
Local Scale ◽  
Snow Accumulation ◽  
Tree Structure ◽  
Scale Model ◽  
Fine Scale ◽  
Individual Tree ◽  
The Impact

Abstract. Understanding the impact of tree structure on snow depth and extent is important in order to make predictions of snow amounts, and how changes in forest cover may affect future water resources. In this work, we investigate snow depth under tree canopies and in open areas to quantify the role of tree structure in controlling snow depth, as well as the controls from wind and topography. We use fine scale terrestrial laser scanning (TLS) data collected across Grand Mesa, Colorado, USA, to measure the snow depth and extract horizontal and vertical tree descriptors (metrics) at six sites. We apply the Marker-controlled watershed algorithm for individual tree segmentation and measure the snow depth using the Multi-scale Model to Model Cloud Comparison algorithm. Canopy, topography and snow interaction results indicate that vegetation structural metrics (specifically foliage height diversity) along with local scale processes such as wind are highly influential on snow depth variation. Our study specifies that windward slopes show greater impact on snow accumulation than vegetation metrics. In addition, the results emphasize the importance of tree species and distribution on snow depth patterns. Fine scale analysis from TLS provides information on local scale controls, and provides an opportunity to be readily coupled with airborne or spaceborne lidar to investigate larger-scale controls on snow depth.

scholarly journals Development of a plume-in-grid model for industrial point and volume sources: application to power plant and refinery sources in the Paris region

2013 ◽  
Vol 6 (4) ◽  
pp. 5863-5900
Author(s):  
Y. Kim ◽  
C. Seigneur ◽  
O. Duclaux
Keyword(s):  
Power Plant ◽  
Grid Size ◽  
Oil Refinery ◽  
Scale Model ◽  
Eulerian Model ◽  
Voc Emissions ◽  
Secondary Aerosols ◽  
Gaussian Puff ◽  
The Impact ◽  
Gaussian Puff Model

Abstract. Plume-in-grid (PinG) models incorporating a host Eulerian model and a subgrid-scale model (usually a Gaussian plume or puff model) have been used for the simulations of stack emissions (e.g., fossil fuel-fired power plants and cement plants) for gaseous and particulate species such as nitrogen oxides (NOx), sulfur dioxide (SO2), particulate matter (PM) and mercury (Hg). Here, we describe the extension of a PinG model to study the impact of an oil refinery where volatile organic compound (VOC) emissions can be important. The model is based on a reactive PinG model for ozone (O3), which incorporates a three-dimensional (3-D) Eulerian model and a Gaussian puff model. The model is extended to treat PM, with treatments of aerosol chemistry, particle size distribution, and the formation of secondary aerosols, which are consistent in both the 3-D Eulerian host model and the Gaussian puff model. Furthermore, the PinG model is extended to include the treatment of volume sources to simulate fugitive VOC emissions. The new PinG model is evaluated over Greater Paris during July 2009. Model performance is satisfactory for O3, PM2.5 and most PM2.5 components. Two industrial sources, a coal-fired power plant and an oil refinery, are simulated with the PinG model. The characteristics of the sources (stack height and diameter, exhaust temperature and velocity) govern the surface concentrations of primary pollutants (NOx, SO2 and VOC). O3 concentrations are impacted differently near the power plant than near the refinery, because of the presence of VOC emissions at the latter. The formation of sulfate is influenced by both the dispersion of SO2 and the oxidant concentration; however, the former tends to dominate in the simulations presented here. The impact of PinG modeling on the formation of secondary organic aerosols (SOA) is small and results mostly from the effect of different oxidant concentrations on biogenic SOA formation. The investigation of the criteria for injecting plumes into the host model (fixed travel time and/or puff size) shows that a size-based criterion is recommended to treat the formation of secondary aerosols (sulfate, nitrate, and ammonium), in particular, farther downwind of the sources (from about 15 km). The impacts of the PinG modeling are less significant in a simulation with a coarse grid size (10 km) than with a fine grid size (2 km), because the concentrations of the species emitted from the PinG sources are relatively less important compared to background concentrations when injected into the host model.

scholarly journals A Local Scale Modeling Study of Mercury Depletion Event at Canadian Arctic

2021 ◽  
Author(s):  
Minish Panchall
Keyword(s):  
Measurement Data ◽  
Canadian Arctic ◽  
Elemental Mercury ◽  
Local Scale ◽  
Atmospheric Mercury ◽  
Scale Model ◽  
Mercury Species ◽  
Time Step ◽  
Gaseous Elemental Mercury ◽  
Modeling Study

A modeling study was conducted on the transformation and deposition patterns of atmospheric mercury in the Canadian Arctic. One Dimensional (1-D) local scale model was used to simulate the episodic depletions of gaseous elemental mercury (GEM) after polar sunrise at Alert, Canada. The model was developed by starting with existing meteorological model (LCM-Local Climate Model) which is coupled with Canadian Aerosol Module (CAM) and then adding modules specific to atmospheric mercury chemistry. The model is able to simulate local scale transport of mercury over the entire depth of the troposphere with a basic time step of 20 min. and incorporates current knowledge of transformation reactions of atmospheric mercury species. Three mercury species Hg(O), Hg(II) and Hg(p) were considered. The developed model was applied to a portion of the Canadian Arctic region, Alert, for the month of April 2002. The model was then evaluated by comparing model estimates of mercury species concentrations with the measurement data collected in the Canadian Arctic by Meteorological Services of Canada, Downsview, Ontario. The results from this modeling study agree reasonably well with some underestimation caused by lower conversion of gaseous elemental mercury (GEM) into reactive gaseous mercury (RGM) and subsequent conversion to total particulate mercury (TPM). A sensitivity analysis was also conducted to examine the depositions of mercury species in response to changes in ozone and soot concentrations.

Local and Landscape Habitat Associations of Shorebirds in Wetlands of the Sacramento Valley of California

2015 ◽  
Vol 6 (1) ◽  
pp. 29-43 ◽  
Author(s):  
Matthew E. Reiter ◽  
Mike A. Wolder ◽  
Jennifer E. Isola ◽  
Dennis Jongsomjit ◽  
Catherine M. Hickey ◽  
...  
Keyword(s):  
Species Richness ◽  
Surface Water ◽  
Local Scale ◽  
Habitat Associations ◽  
Management Unit ◽  
Scale Model ◽  
Early Winter ◽  
Sacramento Valley ◽  
Surrounding Landscape ◽  
Wetland Types

Abstract The Sacramento Valley of California is a site of international importance for shorebirds despite having lost >90% of its historic wetlands. Currently both managed wetlands and flooded agriculture are important habitats for shorebird populations, but the extent of flooded agriculture may be declining in early winter when shorebirds need to acquire resources postmigration to survive winter. We employed long-term shorebird monitoring data to evaluate factors influencing abundance and species richness of shorebirds using the Sacramento National Wildlife Refuge Complex in early winter (November–December) between 2000 and 2009. We quantified the effect of local attributes of the wetland management unit (wetland type, size, and topography) as well as factors in the surrounding landscape (proportion of surface water and housing density) using generalized linear mixed models. We assessed a local-scale model, including covariates representing the area of six wetland types within the management unit, an index to the proportion of the management unit that had a tapered-edge (i.e., topography where flooded areas grade to exposed shoreline then upland), and a year effect. In this local-scale model, shorebird abundance had a significant positive association with the area of seasonally flooded marsh (SFM) and summer water. Topographical variation, characterized by the amount of tapered-edge, also had a significant positive effect on the abundance of shorebirds and species richness. Because >70% of the shorebirds were counted in SFM, we removed all wetland types except SFM to evaluate landscape covariates. Using only SFM-dominated units, there was a significant nonlinear association with the area of SFM within a management unit, with 40–95-ha wetlands having the highest shorebird abundance and species richness. On a landscape scale, the amount of flooding within a 10-km buffer was the best supported model of shorebird abundance and suggested the highest shorebird abundance in a management unit to be expected when 15–45% of the surrounding landscape was flooded. Species richness was positively associated with the proportion of surface water within 2- and 5-km buffers. We identified zones with a predicted high shorebird response to SFM, and assessed that only 6% of potential wetland areas in those zones have permanent conservation status. Our analyses suggest that shorebird abundance and species richness vary nonlinearly as a function of both local and landscape factors, and thus both spatial scales should be considered when developing conservation and management strategies.

scholarly journals Regional and global modeling of aerosol optical properties with a size, composition, and mixing state resolved particle microphysics model

2012 ◽  
Vol 12 (13) ◽  
pp. 5719-5736 ◽  
Author(s):  
F. Yu ◽  
G. Luo ◽  
X. Ma
Keyword(s):  
Optical Properties ◽  
Weather Forecasting ◽  
Transport Model ◽  
Large Fraction ◽  
Size Composition ◽  
Secondary Species ◽  
Carbon Particles ◽  
Clear Sky ◽  
Secondary Particles ◽  
Sky Conditions

Abstract. There exist large uncertainties in the present modeling of physical, chemical, and optical properties of atmospheric particles. We have recently incorporated an advanced particle microphysics (APM) model into a global chemistry transport model (GEOS-Chem) and a regional weather forecasting and chemistry model (WRF-Chem). Here we develop a scheme for calculating regional and global aerosol optical depth (AOD) from detailed aerosol information resolved by the APM model. According to GEOS-Chem-APM simulations, in most parts of the globe, the mass of secondary species resides mainly within secondary particles (60–90%), but in certain regions a large fraction (up to 50–80%) can become coated on various primary particles. Secondary species coated on black carbon and primary organic carbon particles significantly increase the size and hygroscopicity of these particles and thus impact their optical properties. The GEOS-Chem-APM model captures the global spatial distributions of AOD derived from AERONET, MODIS, and MISR measurements, generally within a factor of ~2. Our analysis indicates that modeled annual mean AODs at all sky and clear sky conditions differ by ~20% globally averaged and by >50% in some regions. The time series of WRF-Chem-APM predicted AOD over the northeastern United States in June 2008 have been compared to those from seven AERONET sites. Overall, the model mostly captures the absolute values as well as the variations of AOD at the AERONET sites (including dramatic changes associated with the crossing of high AOD plumes). Both GEOS-Chem and WRF-Chem simulations indicate that AOD over the northeastern US is dominated by secondary particles and have large spatiotemporal variations.

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