| 英文摘要 |
An eight photochemical assessment monitoring station network (PAMS) has been constructed since its first station being established in Taichung city in 2002. A set of quality assurance and control routines has gradually evolved into a standardized procedure to ensure data quality. Monitoring data of 55 target compounds from any one of the eight stations can now be assessable to users within two weeks. For certain stations, data length of 4~5 years was achieved and readily assessable in the database with a data completion rate over 85%, which constitutes the most valuable asset in the systematic study of ozone problems in Taiwan. In this annual report, two areas were discussed; they are: (1) quality assurance and control results; (2) data analysis based on PAMS data collected between 2007 and 2008.
With regard to the first part of the discussion, quality control method by relative variation control charts was introduced starting from 2008, so that quality between the eight stations can be easily compared. Based on the data between 2007 and 2008, the two stations in Taipei area had the best stability and thus data quality, whereas the stability of the three recently deployed stations in Yinling, Jiayi, and Tainan Counties (abbreviated as the YJT area) was slightly poorer than that of the two Taipei stations. Overall, the eight stations were within the controlled range of data quality.
With regard to the second part of the discussion, the discussion focuses on three aspects: (1) emissions of volatile organic compounds (VOCs) in the YJT area; (2) indication of long-range-transport (LRT) in Taipei area using PAMS data; (3) adoption of a free software, GrADS, as a common tool to simplify the process of data analysis and display.
In the spring of 2007, the 3 stations previously deployed in Taichung city and Nantou County were relocated to their new locations in the YJT area. Of the three staions, the Taishi station is in the closest proximity of the 6th light petroleum cracking plant, allowing clear observation of emissions of certain VOCs, e.g., ethylene, propylene, and propane, among others, during winter monsoon season, when the prevailing winds were mostly northerly. To post a contrast, a comparison with another urban station (Tainan station) clearly revealed its nature of industrial emissions.
Since 2007, a novel method was developed from the PAMS dataset, namely using the ratios of ethane/butane or ethane/propane as indicators of LRT during events of frontal passage during the winter monsoon period in northern Taiwan. Ratios of ethane/butane increased from 1.0 to 2~4 when the air circulation pattern changed from stagnant (local) to LRT whenever a frontal passage occurred. The increase in ethane/butane ratios was also accompanied by the less pronounced diurnal cycles of ozone and NOx, signaling the arrival of aged air masses from LRT. The chemical and meteorological conditions associated with the frontal passages posed a sharp contrast to the more stagnant and calm weather conditions.
Operation of the PAMS network has advanced into a mature stage over the past few years. Quality assurance/control and training techniques have long been established to ensure the success running of PAMS network, which in term can safe-guard the smooth transition of PAMS’s operation to any future institute in charge.
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