Random walk modeling of wake dispersion for the exhaust tower of an underground tunnel in urban area

In this paper, some experimental studies on the impact of effluent from an exhaust tower of an underground tunnel with special construction are reported. By measuring the flow field downstream of the tower in NJU meteorological wind tunnel, some flow characteristics in the make area were established. Based on these, an advanced random\|walk dispersion model was set up and applied successfully to the simulation of dispersion in the wake area. The modelling results were in accordance with wind tunnel measurements. The computed maximum of ground surface concentration in the building case was a factor of 3-4 higher than that in the flat case and appeared much closer to the source. The simulation indicated that random walk modelling is an effective and practical tool for the wake stream impact assessment.

Effects of Turbulent Dispersion of Atmospheric Balance Motions of Planetary Boundary Layer

New Reynolds' mean momentum equations including both turbulent viscosity and dispersion are used to analyze atmospheric balance motions of the planetary boundary layer. It is pointed out that turbulent dispersion with r 0 will increase depth of Ekman layer, reduce wind velocity in Ekman layer and produce a more satisfactory Ekman spiral lines fit the observed wind hodograph. The wind profile in the surface layer including tur-bulent dispersion is still logarithmic but the von Karman constant k is replaced by k1 = 1 -2/k, the wind increasesa little more rapidly with height.

Study on Conventional Atmospheric Dispersion Models in China,America and Canada

The conventional atmospheric dispersion models used in China (CRADM), America (HPDM) and Canada (AMS) are investigated. The main differences between the three models are described, and the various aspects of CRADM, HPDM and AMS for same input are compared and discussed. Some problems in application of atmospheric dispersion models to environmental impact assessment are analyzed and suggestions for rivision are proposed. Results show that the Briggs plume rise formula in neutral condition overestimates the real rise due to the fact that the accumulative effect of ambient turbulence on plume is not considered in his model.

Study on the Thermal internal Boundary Layer and Dispersion of Air Pollutant in Coastal Area by Numerical Simulation

In this paper, a scheme on a mesoscale dispersion modeling system was set up. The modeling system was used tostudy the turbulence structure of TIBL and dispersion features under shoreline tlimigation situation. The modelingsystem has successfully solved the problem of meteorological input of stochastic dispersion models and exploited anew approach to comprehensive application of this kind of dispersion models.

The Pioneering Works of Professor Duzheng YE on Atmospheric Dispersion,Tibetan Plateau Meteorology,and Air–Sea Interaction

This paper provides an overview of the impacts of the original works of Professor Duzheng YE on a selected set of observational and model studies with which the present author has been associated over the past several decades. The main themes of these works include atmospheric energy dispersion, air–land interactions over the Tibetan Plateau, and El Ni n？orelated air–sea coupling over East Asia.The dispersive behavior of observed atmospheric fluctuations accompanying cold surge events in East Asia is demonstrated. Cold air outbreaks over Korea and southern China are coincident with the successive downstream development of troughs and ridges, with the group velocity of such wave packets being notably faster than the phase propagation speed of individual troughs and ridges. In a more general context, dispersive features are also discernible from lagged teleconnection charts and cross-spectra of observed and model-simulated geopotential height variations on 10–30-day time scales.Using the output from a high-resolution general circulation model, the relative contributions of condensational, sensible, and radiative heating to the atmospheric energy budget over the Tibetan Plateau are documented. The rapid changes of the upper tropospheric Tibetan anticyclone and East Asian mei-yu（＂plum rain＂） precipitation band associated with the development of the Asian monsoon system are described.The principal anomalies in sea level pressure, surface wind, precipitation and sea surface temperature over southeastern China and the Philippine Sea region during El Nio events are presented. The contributions of remote El Nio-related forcing and local air–sea interaction to the occurrence of these anomalies are assessed.

Effect of Change in Rate of Emissions Furan/Dioxin of Public Health Risk on WTE Gede Bage

Bandung, adopted a policy to build Waste to Energy （WTE） systems with a combustion capacity of 500 tons/day. WTE technologies will burn waste that is fed and utilized energy generated to be converted into electrical energy. This technology has the potential to reduce the volume of waste more effectively, but WTE also emit various harmful contaminants, including Polychlorinated Dibenzofurans （PCDF） and Polychlorinated Dibenzo-p-Dioxins （PCDDs）. WTE equipped with air pollution control, so that the emission of harmful contaminants can be controlled and detected continuously. This study only discusses contaminants PCDF and PCDDs, and the effect of air pollution control work against public health risks. In this study, the efficiency of air pollution control is assumed at 0%, 25%, 50%, 75%, 90% and 99%, while the public health risk assessment carried out for the projected 15 years into the future. Public health risk assessment carried out by the calculation of the health risk of carcinogenic （liver cancer）. A causal relationship between the independent variable efficiency of air pollution control with one dependent variable number of liver cancer patients, obtained the simple linear regression equation Y = 76.4592 - 0.7692X.

The comparison of ensemble or deterministic dispersion modeling on global dispersion during Fukushima Dai-ichi nuclear accident

Ensemble forcasting,originally developed for weather prediction,is lately being extended to atmospheric dispersion applications,which is a new,effective methodology for improving the atmospheric dispersion numerical modeling.In March 2011,due to the massive 9.0 earthquakes and ensuing tsunami that struck off the northern coast of the island of Honshu,the Fukushima Nuclear Plant I had the substantial leak of radioactive materials into surrounding environment and atmosphere.To aim at the global dispersion modeling of atmospheric radionuclides from Fukushima Nuclear Accident,this paper presents two approaches of atmospheric dispersion forecasting:ensemble dispersion modeling(EDM) and deterministic dispersion modeling(DDM),conducts the globally dispersion modeling cases for Fukushima nuclear accident,and analyzes and evaluates the simulation results using observation data.In this paper,EDM includes three different perturbation methods:meteorological perturbation method,turbulence perturbation method,and physical parameterization ensemble forecasting method.The simulation results show that the trajectories from EDM have a better performance,which is in better agreement with the atmospheric circulation and observation data; the spread from DDM is slower and not as far as EDM.Additionally,the results from EDM display a better performance in the modeling of transport from Japan to China East Sea on April 4.The reasons for these results are:the techniques of MET and TUR are performed by adding perturbations on mean wind and turbulent velocity,respectively; the various different flow fields will result in far spreading in horizontal and the simulation results closer to observation; PHY is performed by using different diffusion physical parameterizations and produces the perturbations on vertical wind,which results the spreading in smaller range and discontinuous in horizontal.Finally,the comparative analysis between modeling results and observation data shows that all cases results are in good agreement with trends of observed radionuclides surface concentration; however,the modeling surface concentration is smaller than observation,especially in DDM and PHY.Furthermore,the EDM results show that MET and TUR are of more evolutionary advantage than PHY in modeling of average and maximum concentration.Therefore,this study can serve as a reference to atmospheric dispersion and environmental emergency response(EER).

Atmospheric dispersion of chemical,biological,and radiological hazardous pollutants:Informing risk assessment for public safety

Modern society is confronted with emerging threats from chemical,biological,and radiological(CBR)hazardous substances,which are intensively utilized in the chemical,medical,and energy industries.The atmospheric dis-persion of released CBR hazardous pollutants can influence a large percentage of the population owing to their rapid process with extensive spatial coverage.It is important to comprehensively understand the behaviors of the released CBR pollutants in the atmosphere to fully evaluate the risks and protect public safety.In this study,we reviewed the advancements in the atmospheric transport of CBR pollutants,including the urban atmospheric boundary layer,unique concepts,and models for CBR pollutants.We underlined the development of innovative methodologies(e.g.,inverse estimation and data assimilation methods)for the atmospheric transport of acciden-tally released CBR pollutants to reduce uncertainties in emissions and accumulated errors during dispersion by combining numerical models with monitoring data.Finally,we introduced progress in quantitative risk assess-ment,including exposure assessment and dose-response relationships for CBR hazardous pollutants.A framework,source,assimilation,fundamentals,exposure,and risk(SAFER),has been proposed to integrate the key compo-nents in the risk assessment of airborne CBR hazardous pollutants.These methods and models can contribute to effective risk preparedness,prevention,evidence-based policymaking,and emergency response to airborne CBR pollutants.

Spatial distribution,patterns and source contributions of POPs in the atmosphere of Great Mendoza using the WRF/CALMET/CALPUFF modelling system

Global monitoring of Persistent Organic Pollutants(POPs)has allowed the knowledge of levels and distribution around the world as well as the understanding of its transport through the atmosphere.However,there are still some gaps in this regard,especially in some locations,as the case of Great Mendoza,a medium-sized urban area located in the center-west of Argentina.In this work,the WRF/CALMET/CALPUFF modeling system was used to estimate airborne levels of four families of POPs(PCBs,PBDEs,DDTs and HCB)in the study area.The model was validated from measured data obtained from eleven sites using passive air samplers with polyurethane foam disks(PUFs),subsequently analyzed by GC-ECNI/MS.Considering both sets of data,measured and simulated airborne concentrations,five statistical performance metrics were calculated for each family of POP[Mean bias error,(MBE),Fractional Bias(FB),Normalized Mean Square Error(NMSE),Factor of two(Fa2)and Pearson correlation coefficient(r)].Results exhibited a good agreement between modeled and measured data,showing that WRF/CALMET/CALPUFF modeling system predicts POPs airborne concentrations with reasonable accuracy at a local scale.Model output was used to examine the relative source contribution to ground-level concentrations and to assess the spatial variability of the studied POPs in the study area.Source apportionment showed the prevalence of emissions from open burning of municipal solid waste(ranging from 9%to 90%)on the simulated atmospheric concentrations.HCB presented the lowest mean contribution from this activity(37%)but the highest variability(SD=20%),followed by PCBs(69±9%),and PBDEs(84±4%).The spatial pattern obtained from simulations exhibited that both,lowest and highest levels predicted by the model,occurred in areas where no samples were taken,suggesting that the real gradient in the POPs air concentrations would be much greater than those reflected by measured data.This work highlights the usefulness of the implementation of an atmospheric dispersion model,not only in the study of air quality and exposure levels but also as a tool for the proper design of monitoring networks,taking into account the time and cost that sampling campaigns take,and the conclusions that are intended to be made from the analysis of the obtained data.