Introduction
According to Article 6, Paragraphs 2 and 3 of the Air Pollution Control Act, those newly added or modified stationary pollution sources within Class 2 and Class 3 of air pollution prevention regions in which air pollutant emissions quantities reach a certain regulatory scale is required to perform air quality simulation by suitable air quality model and verify the influence will not exceed allowable increment limits of air pollutant concentrations. As Article 8, Paragraph 2 stands, within a total quantity control district that meets air quality standards, those newly installed or modified stationary pollution sources for which pollutant emissions quantities reach a certain scale is required to perform air quality simulation by suitable air quality model and verify the influence will not exceed allowable increment limits within the district. The scientific and technical knowledge and information that the development and application of air quality models need to accomplish their missions spread in all kinds of academic and advisory organizations, which result into the decentralization of resources, duplicate constructions, various qualities, and barriers of information. Taiwan Air Quality Modeling Center (TAQMC) actually is a policy and technique supporting organization with a combination of experts and data resources in the industry, the government and the academics.
In 2002, Taiwan EPA enforced the allowable increase limits of air pollution in the air pollution control act, and the standard requests of air quality modeling in the procedure of environmental impact assessment. Therefore, Taiwan EPA supported to establish “air quality model supporting center”. In fact, it belongs to the role of technical supporting for policy determination in order to laterally integrate the knowledge of production and official related to talent and data resource. The tasks accomplished and relative productions are shown as follows according to the sequence of objectives for this year in the project plan.
Objectives for this year in the project plan
(1) Cooperate in the application and examination of air quality models to be approved.
(2) Assist the Environmental Protection Bureaus (EPB) of counties and cities in technical examinations and consultations of air quality modeling.
(3)Update and pronounce the relative data for the simulations of allowable increment limits of air pollution concentrations.
(4)Assess the benefits of air quality modeling related laws on the air quality improvement
(5)Maintain and update the TAQMC website and consultation service
(6)Evaluate the influence of new development programs on air quality using air quality models
(7)Prepare the input data of meteorology and land surface characteristics for use of AERMOD modeling system
(8)The analysis of impact on Taiwan air quality from the air pollutions emitted in specific abroad areas through transboundary long-range transport.
Execution results
The tasks accomplished in this project are shown as follows according to the sequence of objectives in the plan.
(1) Cooperate in the application and examination of air quality models to be approved
(a)The application form and database for model approval has been substantially completed. These documents will be issued by the competent authority in the next stage. Part of the information in the database has been updated, and the task of maintenance of updating data and the performance review was also implemented in this year. All the relevant information is provided in the web for the users.
(2) Assist the EPB of counties and cities in the technical examinations and consultations of air quality modeling
(a)Application data of emission credit for stationary pollution sources during 2008-2009 were screened to verify the situations of “allowable increase limits” and improvements of such regulation were also suggested. Fifty-one application cases were approved and reviewed in this year.
(b)Two workshops of air quality model simulation and application were held in October 29, 2010 and March 17, 2011.
(3) Update and pronounce the relative data for the simulations regarding allowable increment limits
(a)Four periods of air pollutants’ episodes for PM10 and ozone over seven air quality basins were cited and announced according to two related regulations.
(b)MM5 simulation was completed and evaluated during 2007. The annual standard mean bios (ME) and mean absolute bios (MAE) of temperature are less than 15%, but the ME and MAE of three air basins of Kou-Ping, Yun-Chai-Nan and Chu-Miao exceed over the recommended benchmark values, say 15% and 35%, and also the simulation results of wind direction in I-Lan, Chu-Miao and Northern air basins need to be improved.
(c)The meteorological input files of ISCST3 for all target stations form 2007 to 2009 have been calculated, calibrated, and verified in this year.
(4)Assess the benefits of air quality modeling related laws on the air quality improvement.
(a)The frame and concept of regulations on air quality modeling and PSD between U.S. and Taiwan are quite similar. USEPA developed several guidelines for modeling work in attainment demonstration and development of SIP. These regulations and guidelines cover several topics including the applicability of emission, preferred air quality models selection, input data preparation, and allowable increase limits.
(b)The case study on maximum incremental concentration shows a significant effect of superposition from several emission sources. These results indicate that the regulation and guidelines in Taiwan should be refined to control the cluster emission sources.
(5) Maintain and update the website of TAQMC and consultation service
(a)The database and contents of TAQMC website have been updating during the past year. There are three parts have been added on the website including information security mechanism, functions of download and announcement, updated information of air quality models in USEPA.
(b)The maintenance and management of the website can be executed in the background management system of the website.
(6) Evaluate the influence of new development programs on air quality by air quality models
(a)Compared to the period of 1998-2003, the number of ozone episodes decreased in Northern and Kao-Ping air basins but increased in Central and Yun-Chia-Nan air basins during the period of 2004-2009.
(b)In general, the ozone pollution in Taiwan is tended to VOC-limited over the period of 1998-2009. The number of VOC-limited O3 episodes was increasing in Yun-Chia-Nan air basin, in which the increasing trend is more significant than those in the other air basins.
(7) Prepare the input data of meteorology and land surface characteristics for use of AERMOD modeling system
(a)From the literature review and the tests therein, AERMOD is more accurate than ISC3 in the simulation of dispersion in complex terrain. This is helpful to correct the conservative prediction of the highest concentration by ISC3.
(b)From the experience of preprocessing meteorological data and land surface parameters, we find that the use of AERMOD is much more difficult than ISC3 for common users. To adopt the full advantage of AERMOD, the existing modeling guideline has to be largely revised and the database of necessary raw data for preprocessing the input of AERMOD is required to be prepared in advance.
(8) The analysis of transboundary long-term of air pollutions in specific areas transported on Taiwan air quality.
(a)Based on the simulation results of May and October in 2007, the impact of transboundary long-range transport on the period average of daily maximum ozone concentration in Taiwan is 18.8 ppb. The maximum effect occurs on Northern air basin and is 24.4 ppb. Owing to the continuous increase emission in East Asia, the most severe situation in 2020 will increase 4 to 6 ppb for various air basins in Taiwan.
(b)The impact of transboundary long-range transport on PM10 for the period averaged concentration in Taiwan is 19 g/m3 (29%), while that on PM2.5 is 18 g/m3 (37%).
(c)Based on the three major sources including petrochemical industries, thermal power plants, and highways in the economic area of western side of Taiwan Strait, the increase emission in the future of 2020 is estimated. The increased emissions of TSP, SOx, NOx, and THC are 44509, 60632, 491548, and 116635 tons per year respectively.
(d)Analysis of monthly mean surface flow shows that May is the most significant month. The air parcel could transport into Taiwan with the interaction of lee-side vortex and mesoscale disturbance from western Taiwan Strait area, since the wind speed is weak and the wind direction are variable during this month. Due to the strait channel effect, transportation across the Taiwan Strait is difficult during the other months even with different monsoon (southwesterly in summer or northeasterly in winter). In vertical circulation analysis, it implied from Spring to Summer (April to August) westerly wind in 850 hPa would bring the pollutants into Taiwan, the possibility is quite small during the other months.
