| 英文摘要 |
Large-scale dust storms originated at the Northeastern Chine frequently occur during springtime. Some of the elevated dust particle may be transported long distance through atmospheric circulation to the Taiwan area. The possibly effects of these atmospheric dust particles include the influence on public health, lowering the visibility and even causing aviation safety concerns, reducing solar radiation to the surface, and altering the precipitation processes. Due to its increasing frequency of occurrence during the past decade, it is essential to study the mechanisms controlling the transport of yellow dust to Taiwan, and develop forecasting capability for early warning. The elevation and transport of atmospheric dust particles is controlled by the surface conditions of the source region (deserts) and the regional weather patterns. The goal of this study is to develop an modeling system that can accurately simulation the elevation of dusts as well as their subsequent transport in the regional scales, and to help establishing an early-warning system for the Environmental Protection Agency for alerting the public regarding to their health, and to provide lead time of operation for the dust-sampling group and health effect evaluation group.
The accomplishments of this project include: (1) development of dust storm forecasting models suitable for use in the East Asia region and Taiwan area, this include a TAQM/dust model and NAQPM/dust model; (2) daily watch of the dust storm events by analysis of the synoptic weather patterns and observation data relevant to Asia dust storms; (3) evaluation of the time, duration, area extent and concentration of possible events of dust reaching Taiwan, so as to assist the issue of warnings by the operation center of EPA; (4) built a web site of atmospheric dust forecasting, using calendar-style data bank in exhibiting the movies of dust storm simulation and analysis data.
Among the 7 significant and 2 minor dust events occurred during the Spring of 2002, our forecasting model missed one of the event and false-alarmed the other. The false-alarm case was an event with strong rain scavenging effect, which was not considered in the TAQM/dust model at the time. Improvement has been made to include this rainout mechanism. For the event that was missed by the model, an error in coding was made when modifying the model, such that the event was actually captured but the order of dust concentration was wrong and is thus counted as a missed case. Corrections have been made soon after. For the rest of the events, the forecasting model did fairly well on the arrival time, duration, and area extent, but not as satisfactory in the maximum mass concentrations. An overall evaluation of the performance of our and foreign models was made, and we found that the TAQM/dust model is superior to all other models in forecasting dust events in Taiwan.
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