| Summary: | 碩士 === 國立中央大學 === 大氣物理研究所 === 99 === The O3 and aerosol problem in Taiwan can be locally produced or long-range transported (LRT) from Gobi desert. The LRT of O3 problems are mostly observed during the spring season under the influence of Asian continental outflow. The O3 concentration about 50 to 70 ppb is observed under the impact of LRT while the locally produced O3 concentration can reach up to 100 ppb easily.
To adequately simulate air pollution events in Taiwan, the correct representation of the boundary layer wind, temperature, moisture, flux components and mixing heights, are needed for air quality modeling which are strongly dependent on the boundary layer parameterizations in meteorological models.
In this study, meteorological simulations are performed using Weather Research Forecasting (WRF)(V3.2.1) model by applying two different PBL schemes (YSU and MYJ). Community Multiscale Air Quality (CMAQ) modeling system is performed subsequently to study the effect of the PBL physical processes on the meteorological and air quality simulations.
The comparison focused on two different atmospheric conditions. Case 1 is under the influence of the Asia continental outflow and the air pollutants is long-range transported (LRT) to northern Taiwan. Case 2 is associated with the land-sea breeze flow and the locally generated ozone concentration can reach up to 120 ppb.
The simulation using YSU scheme predicts higher temperature during the night and inducing weaker land breeze flow which would accumulate the NO in the source region. The O3 titration is stronger near the source region and lower in the offshore area. During the daytime, the simulation using YSU scheme predicts higher temperature thus inducing stronger sea breeze flow which would carry the O3 produced in the previous day back into the Taiwan Island. The stronger sea breeze from simulation using YSU would predict higher O3 toward inland and lower O3 in the offshore area than the one using MYJ. Comparison with the observation datasets identifies less bias of the wind speed, temperature and ozone concentration with the simulation using YSU scheme. Wind direction is reasonably captured in both simulations.
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