增加吸濕性氣膠和雨胚對雲微物理及降雨影響之數值模擬：針對暖雲人工增雨

Abstract

本研究利用一個雙矩量總體水物雲微物理模式，探討增加吸濕性巨核或小水滴作為雨胚對雲微物理和降雨過程的影響，試圖分析以上述方式在臺灣的地型雲進行暖雲人工增雨的可行性。本研究針對一個2006年夏季對流個案進行暖雲人工增雨模擬研究，在不同背景氣膠的情況下，分別在不同位置和時間釋放不同份量和大小的吸濕性粒子或水滴。 模擬結果顯示釋放吸濕性粒子的增雨效果比較顯著，在集水區的降雨量最多可增加超過10%，在全臺灣的總平均值也可增加0.5~4.8%不等，在平均大陸性氣膠背景的情況增雨效果更為顯著；相較之下，灑水的增雨效果較不顯著且缺乏一致性。此外，釋放吸濕性粒子對雲中水物的影響顯著，尤其造成冰相粒子之總質量明顯增加，冰相粒子增加所伴隨增強的混合相降雨過程進而對增雨效果有著重要作用；灑水對雲中水物的影響甚微。此外，種雲對大範圍的降雨分佈影響不大，僅對局部地區尺度為數至數十公里大的降雨系統有顯著影響。

In present study, a bulk-formula two-moment cloud microphysics scheme is incorporated into a regional model to evaluate the aerosol effects on cloud microphysics and precipitation of orographic clouds near Taiwan. The effects of artificially introducing hygroscopic GCCN or small water droplets as rain embryos on precipitation would also be evaluated to investigate the possibility of enhancing precipitation in Taiwan by the aforementioned warm-cloud seeding approaches. In this study, a summertime convective system in 2006 is chosen that different amount and size of hygroscopic particles or water droplets is implanted at different locations and time for warm-cloud seeding. The results indicate that flare seeding is more effective to enhance precipitation than spray seeding. Precipitation amount could increase more than 10% at catchment zones, and increased by 0.5 to 4.8% within Taiwan Island, by releasing hygroscopic particles. Also, the seeding effect is found more significantly under the averaged continental type scenario. The effect of spray seeding on precipitation is comparatively insignificant and inconsistent. Moreover, flare seeding significantly increases the amount of hydrometeors, especially the ice hydrometeors. The accompanied invigoration of mixed-cloud processes might play important role in precipitation enhancement. Again, spray seeding affects little on cloud. In addition, the large-area precipitation distribution changes little by seeding, while the local precipitation systems of several to several tenth kilometres in size have been significant modified.