| 英文摘要 |
The purposes of the first year for this project are to study the sea-land breeze and to evaluate its effects on the ambient air quality in Kaoping air basin. Therefore, both the meteorological factors and air pollutant concentrations were measured simultaneously during this study. The field measurements can be classified into two groups: continuous measurements and intensive field measurements. The continuous measurements, which were conducted during mid-October to the end of November, included hourly vertical profiles of wind speed and wind direction, ground micro-meteorological measurements at four sites, and the air quality measurements at Luchu, an off-shore island. The intensive field measurements were conducted during October 21st to 26th, October 31st to November 5th, and November 17th to 20th and includes pibal, the measurement of the vertical profiles for wind speed, wind direction, temperature, relative humidity, pollutant concentrations, particle size distributions and the ozone-sensitivity indicators.
Among the 16 days of intensive field measurements, there were 7 ozone episodic days with 4 days of regional pollution and two days of local pollution. The local ozone pollution all occurred near Linyuan, the major sampling site. The sea-land breeze was very significant during all the measurements. The vertical height of sea breeze was about 500 to 800 m and that of the recirculating flow could reach 1200 m. But the vertical height of land breeze was only about 200 to 400 m. Accompanying with the sea-land breeze, an internal boundary layer could develop up to 400 m near the coast region. Therefore, the mixing height near noon could be only 400 m and the ozone concentrations built up very quickly.
The air pollutant concentrations at Luchu were highly correlated with those at Linyuan with time differences of about two hours. Therefore, the data at Luchu can be used as alarming indicators for air pollution in Kaoping air basin during the daytime. The vertical profiles for SO2 and NOx showed the maximum concentrations at 200 to 400 m, especially during nighttime due to the effects of industrial parks. However, their concentrations generally increased with height up to 600 m during daytime; similar results were found for the concentrations of NMHC. But the NMHC concentrations generally decreased with height during nighttime. The maximum daytime ozone concentrations generally occurred within the 400 m due to the effect of internal boundary layer and the dominant wind direction was NWW. Both the residence and depletion of ozone concentrations were found during nighttime with three layers of ozone depletion: less than 400 m, 400 to 600 m, and 800 to 1200m. The ozone depletion generally happened during northern wind and was caused by NO titration from the industrial park emission. The ozone depletion at 800 to 1200m sometimes was with southern wind and further study is needed to determine the causes. The particle size distributions at all heights were with three modes: less than 1 m, 2.4 m, and 4.5 m. Higher particle concentrations were found during the ozone depletion layer, especially for supermicron particles. Therefore, the particle within the ozone depletion layers were mainly from the emission sources directly. Significantly high supermicron particle concentrations up to two or three orders of magnitudes were found occasionally at 1000 to 1400 m and the sources for these particles were still unknown. Based on the measurements of ozone-sensitivity indicators, most of time was NOx-limited.
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