Browsing by Author "Cheng, MT"

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Differences in PM10 concentrations measured by beta-gauge monitor and hi-vol sampler
(2001-11-01)
Chang, CT
;
Tsai, CJ
;
Lee, CT
;
Chang, SY
;
Cheng, MT
In this paper. differences between the 24-h average PM10 concentrations of Wedding beta -gauge monitor and Andersen or Wedding hi-vol sampler were studied. When the deliquescent point is not exceeded, PM10 concentrations of the beta -gauge are close to those of the manual samplers. The ratio of beta -gauge PM10 to Andersen PM10 and Wedding PM10 is 1.08 +/-0.06 and 1.09 +/-0.12, respectively. However, when the deliquescent point is exceeded, water absorption by the inorganics of aerosols leads to higher PM10 concentrations of the beta -gauge compared to those of the manual sampler. The ratio of beta -gauge PM10 to Andersen PM10 and Wedding PM10 is 1.21 +/-0.22 and 1.27 +/-0.15, respectively. However., due to evaporation of water from the aerosols collected on the filter tape of the beta -gauge, differences in PM10 concentrations are much less than theoretically calculated. (C) 2001 Elsevier Science Ltd. All rights reserved.
Quantification on source/receptor relationship of primary pollutants and secondary aerosols from ground sources - Part II. Model description and case study
(2002-01-01)
Chen, CL
;
Tsuang, BJ
;
Pan, RC
;
Tu, CY
;
Liu, JH
A Circuit Trajectory transfer-coefficient model (CTx) is developed in this study based on the parameterization presented in a companion paper (Tsuang et al., Atmos. Environ., in this issue). CTx was tested by applying it to Metropolitan Taipei for the entire year 1998. The model was calibrated in January and verified throughout the year. The results indicate that the correlation coefficients (r) for daily concentrations of CO, NOx, SO2, PM2.5, and PM10 were 0.75, 0.69, 0.39, 0.55 and 0.55, respectively, with biases of the means ranging from 0% to 20% during the verification period. According to contour plots of contributed concentrations to the city, "teleconnections" between source emissions and their contributions to the city can be identified. In addition, the model captures most of the dust episodes except during the periods of Asian dust storms. The sensitivity analysis shows that the calculated PM10 concentration is most sensitive to its dry deposition velocity as well as its emission rate. A more thorough study on the deposition velocity of PM2.5 is suggested. (C) 2002 Elsevier Science Ltd. All rights reserved.