Validation of CALPUFF Applicability within Urban Area

2013 ◽  
Vol 726-731 ◽  
pp. 1813-1816
Author(s):  
Long Xiang Dong ◽  
Hong Chao Zuo ◽  
Wen Cheng Dong
Keyword(s):  
Urban Area ◽  
Single Point ◽  
Urban Canopy ◽  
Tracer Experiment ◽  
Gansu Province ◽  
Canopy Layer ◽  
Tracer Concentration ◽  
Tracer Dispersion ◽  
Simulation Error ◽  
Atmospheric Tracer

An atmospheric tracer dispersion study known as Urban Meteorological and Tracer Experiment was carried out in Yuzhong County, Gansu province in northwest of China, during October of 2011. By using the observational data, the applicability of CALPUFF model based on Gaussian formula was verified within urban area. The results show that (i) CALPUFF model can reasonably reflect the actual observations on the whole, and the high value centers of tracer concentration was changed with wind direction over the urban canopy layer. (ii) The simulated plume central axis has a bias of 10-15° with observations, and the simulation error is very much big at the single point, especially at the ground.

Influence of Urban Canopy Layer on a heavy rainfall over Beijing

2020 ◽  
Author(s):  
minjin ma
Keyword(s):  
Heat Source ◽  
Urban Area ◽  
Heavy Rainfall ◽  
Numerical Study ◽  
Regional Scale ◽  
Urban Canopy ◽  
Anthropogenic Heat ◽  
Coupled Simulation ◽  
Canopy Layer ◽  
Urban Canopy Layer

<p>Urban canopy layer (UCL) is generally considered in numerical study of urban meteorology. The weather research and forecasting Model (WRF) coupled with urban canopy layer scheme is used to simulate a heavy rainfall case in Beijing. Comparative analysis is applied for the case between coupled simulation and non coupled simulation and therefore exhibits the effect of the UCL on the rainfall. Sensitive experiments are performed to investigate anthropogenic heat source and urban area extension to affect the precipitation. The results show that the coupled UCL model has captured the rainfall characteristics at the regional scale. The coupled simulation has improved accuracy of the rainfall area, the peak value and the rainfall duration compared to the non coupled simulation. The main effect achieves as longer duriation of the ascending motions and enhancement of the layers unstabilities. Although the intensity of the vertical motion has a little reduction, the time of the motion has increased 2 hours in a day. Sensitive experiments present an obvious influence on precipitation intensity, precipitation centralization and heat island effect. The precipitation center moves toward the urban center, the accumulated rainfall increases 78.5 mm and the center moves by distance 13 km when anthropogenic heat source is perturbed to double. Urban area extension induces increase of the precipitation area and intensity due to high humidity and ascending motion. The experment also reveals shift of the island heat effect.</p>

scholarly journals Tracer Dispersion through Karst Conduit: Assessment of Small-Scale Heterogeneity by Multi-Point Tracer Test and CFD Modeling

Hydrology ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 168
Author(s):  
Romain Deleu ◽  
Sandra Soarez Frazao ◽  
Amaël Poulain ◽  
Gaëtan Rochez ◽  
Vincent Hallet
Keyword(s):  
Spatial Heterogeneity ◽  
Single Point ◽  
Tracer Tests ◽  
Tracer Test ◽  
Breakthrough Curves ◽  
Cfd Modeling ◽  
Small Scale ◽  
Tracer Concentration ◽  
Tracer Dispersion ◽  
The Impact

Tracer tests are widely used for characterizing hydrodynamics, from stream-scale to basin-wide scale. In karstic environments, the positioning of field fluorometers (or sampling) is mostly determined by the on-site configuration and setup difficulties. Most users are probably aware of the importance of this positioning for the relevance of data, and single-point tests are considered reliable. However, this importance is subjective to the user and the impact of positioning is not well quantified. This study aimed to quantify the spatial heterogeneity of tracer concentration through time in a karstic environment, and its impact on tracer test results and derived information on local hydrodynamics. Two approaches were considered: on-site tracing experiments in a karstic river, and Computational Fluid Dynamics (CFD) modeling of tracer dispersion through a discretized karst river channel. A comparison between on-site tracer breakthrough curves and CFD results was allowed by a thorough assessment of the river geometry. The results of on-site tracer tests showed significant heterogeneities of the breakthrough curve shape from fluorometers placed along a cross-section. CFD modeling of the tracer test through the associated discretized site geometry showed similar heterogeneity and was consistent with the positioning of on-site fluorometers, thus showing that geometry is a major contributor of the spatial heterogeneity of tracer concentration through time in karstic rivers.

scholarly journals Vertical Tracer Concentration Profiles Measured during the Joint Urban 2003 Dispersion Study

2007 ◽  
Vol 46 (12) ◽  
pp. 2019-2037 ◽  
Author(s):  
Julia E. Flaherty ◽  
Brian Lamb ◽  
K. Jerry Allwine ◽  
Eugene Allwine
Keyword(s):  
Urban Landscape ◽  
Ground Level ◽  
Concentration Profiles ◽  
Tracer Gas ◽  
Tracer Concentration ◽  
Measured Concentration ◽  
Tracer Dispersion ◽  
Open Country ◽  
Using Data ◽  
Atmospheric Tracer

Abstract An atmospheric tracer dispersion study known as Joint Urban 2003 was conducted in Oklahoma City, Oklahoma, during July of 2003. As part of this field program, vertical concentration profiles were measured at approximately 1 km from the downtown ground-level tracer gas release locations. These profiles showed that the urban landscape was very effective in mixing the plume vertically. In general, the lowest concentration measured along the profile was within 50% of the highest concentration in any given 5-min measurement period. The general slope of the concentration profiles was bounded by a Gaussian distribution with Briggs’s urban equations (stability classes D and E/F) for vertical dispersion. However, measured concentration maxima occurred at levels above the surface, which would not be predicted by Gaussian formulations. Variations in tracer concentration observed in the time series between different release periods were related to changes in wind direction as opposed to changes in turbulence. This was demonstrated using data from mobile analyzers that captured the width of the plume by traveling east to west along nearby streets. These mobile-van-analyzer data were also used to compute plume widths. Plume widths increased for wind directions at larger angles to the street grid, and a simple model comprising adjusted open-country dispersion coefficients and a street channeling component, were used to describe the measured widths. This dispersion dataset is a valuable asset not only for developing advanced tools for emergency-response situations in the event of a toxic release but also for refining air-quality models.

scholarly journals Willingness to Stop Smoking: A Cross-Sectional Study of a Primary Healthcare Center Visitors’ in an Urban Area of Alexandria in Egypt

2020 ◽  
Author(s):  
Rehab A. Rayan
Keyword(s):  
Smoking Cessation ◽  
Urban Area ◽  
Primary Healthcare ◽  
Health Hazard ◽  
Single Point ◽  
Cross Sectional Study ◽  
P Value ◽  
Sectional Study ◽  
Cross Sectional ◽  
Stop Smoking

For improving accomplished attempts to stop smoking, it is necessary to learn about the qualities of individuals who can willingly stop smoking. This study seeks to discover the willingness degree and associated determinants to stop smoking between adult visitors of a primary healthcare centre in an urban area of Alexandria in Egypt. In this single point and descriptive cross-sectional study, a semi-structured questionnaire was distributed to a sample of 53 adults aged ≥18 years in May 2019. Descriptive statistical analyses were conducted to evaluate the determinants influencing the willingness to stop smoking. Of the 53 respondents (with a mean age of 38.7 years old), 41.5% of them were males. Almost 18.9% of the respondents were ongoing smokers (36.4% of males and 6.5% of females), though 83.7% of those smokers were willing to stop smoking. The number of male smokers was significantly greater than female smokers (Pearson Chi-Square = 7.52, p-value = 0.006). Determinants, which can favourably influence the willingness to stop smoking, were believing that smoking is a health risk to them (100%) and the others around (94.3%). A bulk of participants (56.6%) doubted the need for nicotine supplements to help in smoking cessation. Smoker respondents were willing to stop smoking. Understanding that smoking is a health hazard for both smokers and the others around can motivate smoking cessation. Relying on nicotine supplements alone might not add favourably to a strong smoking cessation decision. Tailoring campaigns to raise awareness about smoking health hazards’ would support and sustain smoking cessation.

scholarly journals Application of the WRF/Chem v.3.6.1 on the reanalysis of criteria pollutants over Metro Manila

2019 ◽  
Vol 29 (1) ◽  
Author(s):  
Jacob Alberto Garcia ◽  
Edgar Vallar ◽  
Maria Cecilia Galvez ◽  
Gerry Bagtasa
Keyword(s):  
Time Series ◽  
Urban Areas ◽  
Urban Canopy ◽  
Cold Bias ◽  
Canopy Layer ◽  
Criteria Pollutants ◽  
Pollutant Concentrations ◽  
Significant Difference ◽  
Metro Manila ◽  
Student’S T

AbstractMetro Manila, Philippines and other urban areas have reached internationally known unacceptable levels of pollution where about 80% can be attributed to vehicular emissions. The Weather Research and Forecasting model coupled with Chemistry v.3.6.1 was used in the reanalysis of pollutant concentrations for the year 2013. Initial results from the planetary boundary layer study suggested that the Yonsei University scheme provides a good estimate of the atmosphere’s condition; hence, this setting was used for the succeeding simulations. The land coverage over Sangley point was not properly resolved by the model. This caused a cold bias for the station. Further evaluation of the model’s sea level pressure output for all sites returned high correlations showing that modeled values are in phase with the observed time series; however, wind speed values did not correlate well with the observed values and were all overestimated. The low correlations found were a result of the incapability of the model to detect the urban canopy layer over Metro Manila. Pollutant concentrations were overestimated. The pollutant time series suggests that the model overestimates concentration values for PM10, PM2.5, and SO2, while underestimating NO2 and O3 values. However, it does capture a significant 24-hourly cycle as seen in the time series’ spectra in the frequency domain. Furthermore, through a student’s t-test, the model also captures a significant difference in daytime and nighttime concentrations.

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