Tsai Ying I, Kuo Su-Ching, Lee Wen-Jhy, Chen Chien-Lung, Chen Pei-Ti
Department of Environmental Engineering and Science, Chia Nan University of Pharmacy and Science, 60, Sec. 1, Erh-Jen Rd., Jen-Te, Tainan, Taiwan 717, ROC.
Sci Total Environ. 2007 Sep 1;382(2-3):324-41. doi: 10.1016/j.scitotenv.2007.04.048. Epub 2007 Jun 4.
Visibility trends on the island of Taiwan were investigated employing visibility and meteorological (1961-2003), and air pollutant (1994-2003) data from one highly urbanized center (Taipei), one highly industrialized center (Kaohsiung), and two rural centers (Hualien and Taitung). Average annual visibility (1961-2003) was significantly higher at the rural centers. Unlike at the other centers, visibility in Taipei improved between 1992 (6.6 km) and 2003 (9.9 km), and this can be linked to the construction and expansion of a mass transit rail system in Taipei, the use of which has helped reduce emissions of traffic related air pollutants, particles, and NO2. This has left Kaohsiung with the lowest annual visibility since 1994, despite its 1961-2003 average being superior to that of Taipei. Precipitation lowers visibility, as demonstrated by the all-centers correlation coefficient for visibility and precipitation of -0.92. Hence, frequency of precipitation is one of the factors contributing to the average annual visibility number. The poorest air quality category ('episode'), most commonly experienced in Taipei and Kaohsiung, was characterized by relatively high concentrations of PM10 and NOx at those centers, with comparatively high atmospheric pressure and comparatively low visibility and wind speed. Excepting O3, pollutant concentrations were slightly higher during weekdays, although there was no consistent, significant difference in weekday-weekend visibility. Principal component analysis demonstrated that visibility was markedly reduced in Taipei, Kaohsiung, and Hualien by increased vehicular emissions, road traffic dust, and industrial activity, but not in Taitung, where visibility was as a result superior to that at the other centers and degradation in visibility was likely a response to long-range transport of pollutants rather than local sources. Optimal empirical regression models indicated a negative impact on visibility for each of PM10, SO2 and NO2, particularly so for PM10, and validity of these models for Taipei, Kaohsiung, and Hualien was confirmed by correlation coefficients of simulated and observed average visibility of 0.63-0.72 for daily visibility and 0.85-0.88 for monthly visibility. For Taitung these figures were only 0.46 and 0.50, respectively, indicating that simulations for Taitung should include long-range transport as a pollutant source.
利用来自一个高度城市化中心（台北）、一个高度工业化中心（高雄）以及两个农村中心（花莲和台东）的能见度和气象数据（1961 - 2003年）以及空气污染物数据（1994 - 2003年），对台湾岛的能见度趋势进行了调查。农村中心的年平均能见度（1961 - 2003年）显著更高。与其他中心不同，台北的能见度在1992年（6.6公里）至2003年（9.9公里）之间有所改善，这可能与台北大众捷运铁路系统的建设和扩展有关，该系统的使用有助于减少与交通相关的空气污染物、颗粒物和二氧化氮的排放。尽管高雄1961 - 2003年的平均能见度高于台北，但自1994年以来其年能见度却是最低的。降水会降低能见度，能见度与降水的全中心相关系数为 -0.92就证明了这一点。因此，降水频率是影响年平均能见度数值的因素之一。台北和高雄最常出现的最差空气质量类别（“污染事件”）的特征是这些中心的可吸入颗粒物（PM10）和氮氧化物浓度相对较高，气压相对较高，能见度和风速相对较低。除臭氧外，工作日的污染物浓度略高，不过工作日和周末的能见度没有持续、显著的差异。主成分分析表明，台北、高雄和花莲的能见度因车辆排放增加、道路交通扬尘和工业活动而显著降低，但台东并非如此，台东的能见度因此高于其他中心，其能见度下降可能是对污染物长距离传输而非本地源的响应。最优经验回归模型表明，PM10、二氧化硫（SO2）和二氧化氮中的每一种都对能见度有负面影响，尤其是PM10，台北、高雄和花莲的这些模型的有效性通过日能见度模拟值与观测值的相关系数0.63 - 0.72以及月能见度的相关系数0.85 - 0.88得到证实。对于台东，这些数字分别仅为0.46和0.50，这表明对台东的模拟应将长距离传输作为污染物来源。
