| Summary: | 碩士 === 國立臺灣大學 === 環境工程學研究所 === 101 === Many air quality models developed from the USA have been widely utilized in Taiwan. However, in these modeling systems, many of default surface parameters are set for the topographic and climatic conditions in the USA, which are quite different from those in Taiwan. In addition, the simulation of diffusion patterns of air pollutant is directly affected by the estimation of the atmospheric stability, which can be quantified from the sensible heat flux. In many studies, the utilization of Bowen ratio by using different approaches are commonly used to calculate sensible heat fluxes and further determine the atmospheric stability used in air quality models . However, very few studies discuss the comparison among these approaches by using local measurement. Therefore, the objective of this research is to determine the localized surface parameters suitable in AERMOD for the conditions in Taiwan, to improve the determination of atmospheric stability and the performance of air quality models.
To achieve the abovementioned objective, in these researches, the widely used Penman-Monteith (PM) and Priestley –Taylor (EPA) formulas are being conducted to provide the quantitative basis for atmospheric stability. To verify the performance of these approaches, the measurement data collected by using eddy-covariance technique at Guandu grassland is applied in this study.
In this study, Penman-Monteith and Priestley –Taylor formulas are applied to the study area, Guandu. The canopy resistance of Penman-Monteith formular is about 100 (sm-1). The Bowen ratio calculated by Penman-Monteith formula has a higher correlation with the Bowen ratio calculated by eddy covariance. The Bowen ratio calculated by Priestley –Taylor formula is only affected by temperature. Then, input two of the Bowen ratios above to the AERMOD and then take the number calculated by eddy covariance as the real value. We found out that the correlation with pollutant concentration using default Bowen Ratio and real pollutant concentration is irrelevant. Furthermore, the pollutant concentration calculated by default Bowen Ration underestimated much more seriously.
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