| 摘要: | 本研究主要探討都會地區（台北、台南、高雄）與非都會地區（台東、花蓮）影響能見度因子的關聯性，研究期間含括自1961~2003年之氣象因子及1994~2003年之空氣品質參數（SO2，CO，O3，NOX and PM10）。藉由主成分因子分析（Principal Component Analysis，PCA）及多重變異迴歸模式探討並建立都會地區及非都會地區之能見度與其影響因子之關係。其中探討都會地區與非都會地區之能見度與其影響因子之變異，並探討假日與非假日之能見度差異。本研究地區1961-2003之年平均能見度分別為：8.8±1.5 km (台北)，12.4±4.2 km (台南)，13.9±5.9 km (高雄)，25.7±5.0 km (台東)，22.8±6.9 km (花蓮)，顯示非都會地區之能見度明顯高於都會地區。都會地區的年平均能見度自1960年代的21~25 km降至2003年的4~5 km，且近5年均維持在此低能見度狀態，而非都會地區由33~35 km降低至10~15 km，顯示都會地區能見度明顯低於非都會地區，其原因主要與都會地區空氣品質較非都會地區為差有關，尤其主要影響能見度的PM10，在都會地區明顯高於非都會地區。此外，假日與非假日的污染探討發現，研究地區均存在假日效應(Weekend Effect)，在假日時段的臭氧濃度高於非假日，然以能見度平均而言，假日較非假日平均高約4.4 km，在台南及花蓮之假日能見度顯著與非假日之平均能見度有所差異(p value＜0.05)，而其他地區雖有差異，但未達統計之顯著水準。由PCA之解析發現，能見度與道路交通污染排放有顯著關係，而各地空氣品質除受上述污染影響外，尚有光化二次污染及工業之硫氧化物排放有關。由PM10為污染指標發現PSI＞100時，除PM10呈現高濃度外，空氣污染物NOX亦呈現最高濃度，氣象因子如大氣壓力與風速則分別呈現高氣壓與低風速。由經驗模式推估發現PM10以ln[PM10]為參數可展現對能見度變異有最大影響性。
Principal component analysis (PCA) was employed to analyze variations in visibility compared with: (1) variations in meteorological variables in the period 1961 to 2003, and (2) criteria air pollutant (SO2, CO,O3, NOx and PM10) concentrations monitored between 1994 and 2003 in urban (Taipei, Tainan, Kaohsiung) and suburban (Taitung, Hualien) areas. The visibility discrepancy between weekend and on weekdays was also examined. Average annual visibilities in the work areas during 1961-2003 were 8.8±1.5 km in Taipei, 12.4±4.2 km in Tainan, 13.9±5.9 km in Kaohsiung, 25.7±5.0 km in Taitung and 22.8±6.9 km in Hualien, respectively, demonstrating that visibility in the country areas was significantly exceeded that in the urban areas. Average visibility in the urban areas during the 1960s exceeded 21- 25 km, deteriorated to 4-5 km in the period 2002 to 2003 and remained low in the last 5 years of 1961-2003. Whilst average visibility in the country areas during the 1960s exceeded 33-35 km, it also reduced to 10-15 km during 2002 to 2003. The visibility discrepancy between urban and country areas was mainly resulted from higher air pollution in the urban areas, specially higher PM10 concentration, which influenced the visibility deterioration more than in the country areas. Visibility decreased with concentrations of PM10 in urban areas more than in suburban areas. This study revealed a Weekend Effect (namely weekend ozone concentrations exceed weekday concentrations) throughout the study areas. Weekend visibility exceeded that on weekdays, and particularly weekend visibility was considerably higher than weekday visibility in Tainan and Hualien despite the t-test and P values being less than 0.05. Employed PCA demonstrated that increased vehicular emissions, road traffic dust and industry activities markedly impacted air quality. Pollutant standard index (PSI) was applied daily to judge air quality variations. PSI is calculated using pollutants of PM10 maximum in this study. When PSI values exceeded 100, the concentrations of NOX and atmospheric pressure appeared higher than under normal circumstances, but windspeed was lower when PSI value exceeded 100. Regression results for various empirical models of visibility demonstrated that higher PM10 concentrations implied lower visibility ranges, and the parameter of ln[PM10] represented the most significant impact on visibility. |
