伴隨對流系統的冷空氣外流與地形效應之交互作用

• Main Author: 姚夢真
• Other Authors: 朱昌敏
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/23714774911040790844

碩士 === 中正理工學院 === 應用物理研究所 === 88 === ABSTRACT A two—dimensional nonhydrostatic cloud model has been used to investigate the interactions between cold-air outflows and the mountain in low-Froude number. In early stage, convective system was induced by the terrain forcing over the upslope of the mountain. Subsequently, the evaporative cooling associated with falling rainfall beneath the precipitating cloud could enhance the cold-air outflow. As the cold-air outflow propagated upstream, the interactions between cold-air outflows and the mountain onset. Meanwhile, the gust front associated with the convergence produced by the cold-air outflow and the prevailing flow could trigger new convection under favorable conditions. We also found that the convective system propagates upstream while the individual cell propagated downstream of the mountain. As long as the leading edge of cold-air outflow was still over upslope of the mountain, orographic forcing and cold-air outflow played the same important roles to triggering new cells. As the gust front propagated upstream away from the mountain, the cold-air outflow was the main mechanism to trigger new cell over the plain area. In addition, the eastern flank of the cold-air outflow near the mountain could not propagate downstream due to the block effect of the mountain. In our case study, we also found that the surface radiation, air-sea interaction, and the temperature variation over the boundary layer can significantly influence our simulation due to the subtropical climate of Taiwan. With these factors, model results can be proved similar to real weather observations.