scholarly journals Modeled and observed ozone sensitivity to mobile-source emissions in Mexico City

2008 ◽  
Vol 8 (4) ◽  
pp. 14991-15030 ◽  
Author(s):  
M. Zavala ◽  
W. F. Lei ◽  
M. J. Molina ◽  
L. T. Molina
Keyword(s):  
Mexico City ◽  
Emission Control ◽  
Emission Factors ◽  
Nox Emission ◽  
Base Case ◽  
Mobile Source ◽  
Historical Trends ◽  
Emission Reductions ◽  
Control Policies ◽  
The Past

Abstract. The emission characteristics of mobile sources in the Mexico City Metropolitan Area (MCMA) have changed significantly over the past few decades in response to emission control policies, advancements in vehicle technologies and improvements in fuel quality, among others. Along with these changes, concurrent non-linear changes in photochemical levels and criteria pollutants have been observed, providing a unique opportunity to understand the effects of perturbations of mobile emission levels on the photochemistry in the region using observational and modeling approaches. The observed historical trends of ozone (O3), carbon monoxide (CO) and nitrogen oxides (NOx) suggest that ozone production in the MCMA has changed from a low to a high VOC-sensitive regime over a period of 20 years. Comparison of the historical emission trends of CO, NOx and hydrocarbons derived from mobile-source emission studies in the MCMA from 1991 to 2006 with the trends of the concentrations of CO, NOx, and the CO/NOx ratio during peak traffic hours also indicates that fuel-based fleet average emission factors have significantly decreased for CO and VOCs during this period whereas NOx emission factors do not show any strong trend, effectively reducing the ambient VOC/NOx ratio. This study presents the results of model analyses on the sensitivity of the observed ozone levels to the estimated historical changes in its precursors. The model sensitivity analyses used a well-validated base case simulation of a high pollution episode in the MCMA with the mathematical Decoupled Direct Method (DDM) and the standard Brute Force Method (BFM) in the 3-D CAMx chemical transport model. The model reproduces adequately the observed historical trends and current photochemical levels. Comparison of the BFM and the DDM sensitivity techniques indicates that the model yields ozone values that increase linearly with NOx emission reductions and decrease linearly with VOC emission reductions only up to 30% from the base case. We further performed emissions perturbations from the gasoline fleet, diesel fleet, all mobile (gasoline plus diesel) and all emission sources (anthropogenic plus biogenic). The results suggest that although large ozone reductions obtained in the past were from changes in emissions from gasoline vehicles, currently significant benefits could be achieved with additional emission control policies directed to regulation of VOC emissions from diesel and area sources that are high emitters of alkenes, aromatics and aldehydes.

scholarly journals Modeled and observed ozone sensitivity to mobile-source emissions in Mexico City

2009 ◽  
Vol 9 (1) ◽  
pp. 39-55 ◽  
Author(s):  
M. Zavala ◽  
W. Lei ◽  
M. J. Molina ◽  
L. T. Molina
Keyword(s):  
Mexico City ◽  
Emission Control ◽  
Emission Factors ◽  
Nox Emission ◽  
Base Case ◽  
Mobile Source ◽  
Historical Trends ◽  
Emission Reductions ◽  
Control Policies ◽  
The Past

Abstract. The emission characteristics of mobile sources in the Mexico City Metropolitan Area (MCMA) have changed significantly over the past few decades in response to emission control policies, advancements in vehicle technologies and improvements in fuel quality, among others. Along with these changes, concurrent non-linear changes in photochemical levels and criteria pollutants have been observed, providing a unique opportunity to understand the effects of perturbations of mobile emission levels on the photochemistry in the region using observational and modeling approaches. The observed historical trends of ozone (O3), carbon monoxide (CO) and nitrogen oxides (NOx) suggest that ozone production in the MCMA has changed from a low to a high VOC-sensitive regime over a period of 20 years. Comparison of the historical emission trends of CO, NOx and hydrocarbons derived from mobile-source emission studies in the MCMA from 1991 to 2006 with the trends of the concentrations of CO, NOx, and the CO/NOx ratio during peak traffic hours also indicates that fuel-based fleet average emission factors have significantly decreased for CO and VOCs during this period whereas NOx emission factors do not show any strong trend, effectively reducing the ambient VOC/NOx ratio. This study presents the results of model analyses on the sensitivity of the observed ozone levels to the estimated historical changes in its precursors. The model sensitivity analyses used a well-validated base case simulation of a high pollution episode in the MCMA with the mathematical Decoupled Direct Method (DDM) and the standard Brute Force Method (BFM) in the 3-D CAMx chemical transport model. The model reproduces adequately the observed historical trends and current photochemical levels. Comparison of the BFM and the DDM sensitivity techniques indicates that the model yields ozone values that increase linearly with NOx emission reductions and decrease linearly with VOC emission reductions only up to 30% from the base case. We further performed emissions perturbations from the gasoline fleet, diesel fleet, all mobile (gasoline plus diesel) and all emission sources (anthropogenic plus biogenic). The results suggest that although large ozone reductions obtained in the past were from changes in emissions from gasoline vehicles, currently significant benefits could be achieved with additional emission control policies directed to regulation of VOC emissions from diesel and area sources that are high emitters of alkenes, aromatics and aldehydes.

scholarly journals Application of positive matrix factorization to on-road measurements for source apportionment of diesel- and gasoline-powered vehicle emissions in Mexico City

2009 ◽  
Vol 9 (6) ◽  
pp. 27571-27609 ◽  
Author(s):  
D. A. Thornhill ◽  
A. E. Williams ◽  
T. B. Onasch ◽  
E. Wood ◽  
S. C. Herndon ◽  
...  
Keyword(s):  
Mexico City ◽  
Matrix Factorization ◽  
Vehicle Emissions ◽  
Particle Number ◽  
Emission Factors ◽  
Mobile Laboratory ◽  
Mobile Source ◽  
Positive Matrix ◽  
Engine Exhaust ◽  
Mobile Source Emissions

Abstract. The goal of this research is to quantify diesel- and gasoline-powered motor vehicle emissions within the Mexico City Metropolitan Area (MCMA) using on-road measurements captured by a mobile laboratory combined with positive matrix factorization (PMF) receptor modeling. During the MCMA-2006 ground-based component of the MILAGRO field campaign, the Aerodyne Mobile Laboratory (AML) measured many gaseous and particulate pollutants, including carbon dioxide, carbon monoxide (CO), nitrogen oxides (NOx), benzene, toluene, alkylated aromatics, formaldehyde, acetaldehyde, acetone, ammonia, particle number, fine particulate mass (PM2.5), and black carbon (BC). These serve as inputs to the receptor model, which is able to resolve three factors corresponding to gasoline engine exhaust, diesel engine exhaust, and the urban background. Using the source profiles, we calculate fuel-based emission factors for each type of exhaust. The MCMA's gasoline-powered vehicles are considerably dirtier, on average, than those in the US with respect to CO and aldehydes. Its diesel-powered vehicles have similar emission factors of NOx and higher emission factors of aldehydes, particle number, and BC. In the fleet sampled during AML driving, gasoline-powered vehicles are responsible for 97% of mobile source emissions of CO, 22% of NOx, 95–97% of aromatics, 72–85% of carbonyls, 74% of ammonia, negligible amounts of particle number, 26% of PM2.5, and 2% of BC; diesel-powered vehicles account for the balance. Because the mobile lab spent 17% of its time waiting at stoplights, the results may overemphasize idling conditions, possibly resulting in an underestimate of NOx and overestimate of CO emissions. On the other hand, estimates of the inventory that do not correctly account for emissions during idling are likely to produce bias in the opposite direction. Nevertheless, the fuel-based inventory suggests that mobile source emissions of CO and NOx are overstated in the official inventory while emissions of VOCs may be understated. For NOx, the fuel-based inventory is lower for gasoline-powered vehicles but higher for diesel-powered ones compared to the official inventory.

scholarly journals The impacts of COVID-19, meteorology, and emission control policies on PM2.5 drops in Northeast Asia

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yoon-Hee Kang ◽  
Seunghee You ◽  
Minah Bae ◽  
Eunhye Kim ◽  
Kyuwon Son ◽  
...  
Keyword(s):  
South Korea ◽  
Northeast Asia ◽  
Emission Control ◽  
Anthropogenic Pollution ◽  
Meteorological Conditions ◽  
Anthropogenic Emissions ◽  
Control Policies ◽  
The Public ◽  
The Past ◽  
Quality Modeling

AbstractIn January 2020, anthropogenic emissions in Northeast Asia reduced due to the COVID-19 outbreak. When outdoor activities of the public were limited, PM2.5 concentrations in China and South Korea between February and March 2020 reduced by − 16.8 μg/m3 and − 9.9 μg/m3 respectively, compared with the average over the previous three years. This study uses air quality modeling and observations over the past four years to separate the influence of reductions in anthropogenic emissions from meteorological changes and emission control policies on this PM2.5 concentration change. Here, we show that the impacts of anthropogenic pollution reduction on PM2.5 were found to be approximately − 16% in China and − 21% in South Korea, while those of meteorology and emission policies were − 7% and − 8% in China, and − 5% and − 4% in South Korea, respectively. These results show that the influence on PM2.5 concentration differs across time and region and according to meteorological conditions and emission control policies. Finally, the influence of reductions in anthropogenic emissions was greater than that of meteorological conditions and emission policies during COVID-19 period.

scholarly journals Support vector machine for a diesel engine performance and NOx emission control-oriented model

2020 ◽  
Vol 53 (2) ◽  
pp. 13976-13981
Author(s):  
Masoud Aliramezani ◽  
Armin Norouzi ◽  
Charles Robert Koch
Keyword(s):  
Support Vector Machine ◽  
Diesel Engine ◽  
Emission Control ◽  
Engine Performance ◽  
Nox Emission ◽  
Support Vector

scholarly journals Emission Factors of Black Carbon and Co-pollutants from Diesel Vehicles in Mexico City

2017 ◽  
Author(s):  
Miguel Zavala ◽  
Luisa T. Molina ◽  
Tara I. Yacovitch ◽  
Edward C. Fortner ◽  
Joseph R. Roscioli ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Developing Countries ◽  
Black Carbon ◽  
Mexico City ◽  
Urban Areas ◽  
Fine Particulate Matter ◽  
Emission Factors ◽  
Remote Sensing Technique ◽  
Driving Conditions ◽  
Comparison Of The Results

Abstract. Diesel-powered vehicles are intensively used in urban areas for transporting goods and people but can substantially contribute to high emissions of black carbon (BC), organic carbon (OC), and other gaseous pollutants. Strategies aimed at controlling mobile emissions sources thus have the potential to improve air quality as well as help mitigate impacts of air pollutants on climate, ecosystems, and human health. However, in developing countries there are limited data on the BC and OC emission characteristics of diesel-powered vehicles and thus there are large uncertainties in the estimation of the emission contributions from these sources. We measured BC, OC and other inorganic components of fine particulate matter (PM), as well as carbon monoxide (CO), nitrogen oxides (NOx), sulfur dioxide (SO2), ethane, acetylene, benzene, toluene, and C2-benzenes under real-world driving conditions of 20 diesel-powered vehicles encompassing multiple emission level technologies in Mexico City with the chasing technique using the Aerodyne mobile laboratory. Average BC emission factors ranged from 0.41–2.48 g/kg-fuel depending on vehicle type. The vehicles were also simultaneously measured using the cross-road remote sensing technique to obtain the emission factors of nitrogen oxide (NO), CO, total hydrocarbons, and fine PM, thus allowing the inter-comparison of the results from the two techniques. There is overall good agreement between the two techniques and both can identify high and low emitters but substantial differences were found in some of the vehicles, probably due to the ability of the chasing technique to capture a larger diversity of driving conditions in comparison to the remote sensing technique. A comparison of the results with the US-EPA MOVES-2014b model showed that the model underestimates CO, OC, and selected VOC species whereas there is better agreement for NOx and BC. Larger OC / BC ratios were found in comparison to ratios measured in California using the same technique, further demonstrating the need for using locally-obtained diesel-powered vehicle emission factors database in developing countries in order to reduce the uncertainty in the emissions estimates and to improve the evaluation of the effectiveness of emissions reduction measures.

scholarly journals Measuring Job Performance of The Economic Creative Business upon Women Enterpreneurs Base (Case Study at Online Bunda Community Bogor Branch Using Balance Scorecard Approach)

2018 ◽  
Vol 3 (1) ◽  
pp. 67
Author(s):  
Indar Khaerunnisa
Keyword(s):  
Job Performance ◽  
Online Community ◽  
Business Processes ◽  
Secondary Data ◽  
Base Case ◽  
Balance Scorecard ◽  
The Past ◽  
Financial Perspective ◽  
Coverage Measurement

Balance scorecard has a privilege in terms of coverage measurement whichis a fairly comprehensive because while taking into consideration the financialperformance. Balance scorecard also consider the performance of non-financialperformance, namely customer, internal business processes, and learning and growth.Referring to the problems encountered by Member of Bunda Online Community, thisresearch examines: "Analysis of Company's Performance by Using BalancedScorecard Approach (A Case Study Economic Creative Entrepreneur at Bunda OnlineCommunity)." Because until now Bunda Online Community has not been using thebalanced scorecard to measure its job performance. The population of this study arepermanent employees and 100 samples are taken as respondents. As for thecustomer respondents specified by 52 respondents total reseller and costumer inBogor is only 52 reseller and costumer, however, it has obtained only 30 respondentswho participated. Data used in this study are primary and secondary data. Based onthe research and analysis, it can be concluded several things as the following: 1) Theperformance of the financial perspective on Economic Creative Entrepreneur in BundaOnline Community as a whole can be inferred or quite enough, in general financialratios increased except ROA and TATO. 2) The performance of the customerperspective on Economic Creative Entrepreneur in Bunda Online Community as awhole can be inferred bad, because of poor customer satisfaction in the company'sability to maintain customer retention is also bad while in the company's ability to docustomer acquisition is medium. 3) The performance of internal business processperspective on Economic Creative Entrepreneur in Bunda Online Community isenough, because innovation occurs only once during the past two years and there isnot declining operating activities due to consistent time on the production clothingprocess. 4) The performance of learning and growth perspective in the EconomicCreative Entrepreneur in Bunda Online Community may be concluded either onaspects of employee turnover or both criteria which decreasing employee productivity.Level of employee satisfaction is concluded less satisfied.

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