The deterioration of air quality is strongly related to the meteorological condition. A better understating on the microscale, mesoscale, and PBL meteorology can effectively help the implement of air quality forecast and analysis. In the past decades, the Southeast Asia has experienced remarkable economic and population growth. The large increase in various types of factories, human activities, and biomass burning decreased the air quality over this region. The local air pollution of Taiwan gets more attention recently. High PM2.5 concentration events occur frequently in Central and Southern Taiwan, not only due to the emissions but also the weak atmospheric diffusion condition. Therefore, understanding the thermodynamics structure within PBL can help to clarify the cause of deteriorating air quality. Although the EPA Taiwan Air Quality Monitoring network provides the air quality information at the ground level, it cannot explain the PM2.5 characteristics in vertical. Therefore, observing the aerosol optical characteristics in the vertical direction by using remote sensing techniques, which can monitor the change of pollutants over time and space, is complementary for air quality monitoring.
The objectives and task of this project are: (1) to execute the operation and maintenance of the Micro-pulse lidar systems of three stations in Taiwan；(2) to assist in planning and establishing permanent stations and supporting matters；(3) to offer professional consulting for micro-pulse lidars and sunphotometers, and site safety information for station operating；(4) to build the lidar observation database and accomplish the operations of data QA/QC；(5) to integrate the observational data based on EPA MPL systems and air quality monitoring station, and further analyze the possible causes of high pollution events；(6) to establish the experience with lidar data and offer the daily data report, as well as supporting air quality forecast；(7) to offer the data analyzation of unexpected high pollution events；(8) to upgrading the techniques and equipment conform to the standard of Asia reference station, and intensify the replacement of components for maintaining the stations and equipment.
The important achievements from this project are listed as follows:
• We had established the SOP flow chart for each maintenance work, including station location choosing, instrument operating and maintaining, AP/DC calibration procedure, annual inspection, data transmission and retrieving, high pollution case analyzation, and the instrument moving for emergencies. We also provided advices about the supporting equipment lists to improve the function of lidar stations, the issues which affect lidar observation. We had set up the 4G device servers for each permanent station in 2019.
• We had established the data management procedure and QC flag table, especially for the instrument repaired, power abnormal, and so on. We had executed the AP/DC calibration and data QA/QC procedure on schedule to ensure the availability and stability of MPL data. The MPL data has been posted to webpages and database real time and update to EPA server simultaneously.
• We applied a statistical method to define the high pollution events in this year and set up a database for case studies. We systematically analyze those pollution events with observational data obtained from EPA MPL system and air quality monitoring stations in Taiwan. We explained the causes of high pollution events based on multiscale analysis including vertical and horizontal distribution of particulate matters and meteorological conditions. The results from those case studies significantly improve our understanding on the air quality deterioration. To enhance the analysis of high polluted events, we provided and developed a retrieval process of planetary boundary layer heights and the leeward-side vortex analyses.
• We had upgraded EPA NCU MPL station with capability for high quality measurement and meet to the standard of Asia reference station. We intensified the techniques of data retrieving, and upgraded the calibrating equipment to establish an environment for MPL inter-comparison.
• We continued to cooperate with NASA MPLNET. The chair of MPLNET and the main engineering staff came to Taiwan for discussing data retrieval techniques, inspecting Asian reference station, and educating the techniques on calibrating and replacing components. We also sent our members to visit the Japan NIES and Waseda University in Japan, and visit UMBC and Sigmaspace company (now Geosystems) in the US.
