Modeling of ozone precursors and their transformation into ground-level ozone in urban environment in Malaysia

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dc.contributor.authorGhazali, Nurul Adyani
dc.date.accessioned2015-06-03T05:18:38Z
dc.date.available2015-06-03T05:18:38Z
dc.date.issued2010
dc.description.abstractOzone (03) is one of the major problems of air pollution around the world due to its ability to cause adverse effect to human health and environment. Hence, it is important to develop 0 3 prediction model to give the early warning to public. The hourly observations of 0 3 and nitrogen oxides (N Ox) concentrations together with the weather parameters were monitored from five study areas in Malaysia. The observations were obtained over five year period from 2003 to 2007. Times series plot was used to explain the transformation of nitrogen dioxide (N02) into 0 3 at urban environment of Malaysia. The findings proved that the peak concentration of 0 3 occurs during noon when highest UVB intensity and temperature recorded. By using multiple linear regression analysis, 0 3 prediction daytime and night time models for each study areas were developed based on its precursors; N02 concentration, nitric oxide (NO) concentration, Non-methane Hydrocarbon (NmHC), total hydrocarbon (THC) and also meteorological parameters such as ultraviolet radiation (UVB), temperature, humidity, wind speed and wind direction as the predictors. These data were analyzed using linear regression methods in order to set up the tool for future prediction of 0 3 concentration. Coefficient of determination (R 2 ) was calculated to show the degree of linearity between 0 3 concentrations with other prediction variables. From the regression model, the predicted values of 0 3 concentration were observed. Prediction of 0 3 concentrations was carried out and scatter plot of observed 0 3 concentrations versus predicted 0 3 concentrations was plotted for developed models verification. Among the meteorological parameters, UVB and temperature tend to contribute significantly to high 0 3 concentrations. Besides that, wind speed and wind direction also affect the accumulation of precursor and affect the 0 3 concentrations indirectly. The influences of the different previous hour 0 3 concentrations on the next hour concentrations was also demonstrated and proved that previous one hour 0 3 concentrations influence the most for the next hour concentrations. Performance indicators analysis was then carried out based on the normalised absolute error (N AE), prediction accuracy (P A), coefficient of determination (R2), root mean square error (RMSE) and index of agreement (IA) and the best fit models for all the three study areas were determined. To determine the accuracy of the values, plots of predicted 0 3 concentration against observed 03 concentration were done. The 95 %confidence interval was found. From the study, the measured coefficients of determination for all models are above 0.8; however the overall accuracy for predicted models is approximately 95 %.en_US
dc.identifier.urihttp://hdl.handle.net/123456789/795
dc.language.isoenen_US
dc.subjectOzone precursorsen_US
dc.subjectUrban environmenten_US
dc.titleModeling of ozone precursors and their transformation into ground-level ozone in urban environment in Malaysiaen_US
dc.typeThesisen_US
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