雲凝結核濃度對於納莉(2001)颱風於海洋環境之影響

陳寰(Huan Chen)

指導教授 ： 楊明仁

國立中央大學/地球科學學院/大氣物理研究所/碩士(2014年)

摘要

過去許多研究利用不同雲微物理參數化方法針對於颱風進行模擬,瞭解其對
於颱風路徑、強度、結構及降水之影響,但對於雲凝結核濃度對颱風研究之模擬 實驗則較少。近年來,由於氣溶膠對於大氣環境影響的研究逐漸被重視,又由諸 多前人研究顯示,氣溶膠濃度的變化確實在雲微物理過程中扮演重要的角色,故 需針對此一課題進行深入研究。
因此本研究將使用 WRF 模式,針對納莉颱風(2001)進行一系列的數值模擬 研究。本研究使用 WRF 模式中之 WDM6 雲微物理方案,修改其雲凝結核初始 數量濃度(大陸型、半大陸型及海洋型濃度),並去除地形影響,進行海洋環境的 模擬實驗。由模擬結果發現,若增加初始雲凝結核濃度,則使得大氣中形成的雲 滴粒子數量較多,粒徑較小,藉由颱風眼牆區域的強烈上升運動傳至高層出流區, 得以傳輸至離颱風中心較遠處。因此造成眼牆及外圍雨帶區域降水強度不同,各 水象粒子的空間分佈也有所不同,從液態凝結與冰相凝華潛熱加熱率垂直剖面來 看也有所差異,因此大氣環境中雲凝結核濃度的不同,對於熱帶氣旋的強度與結 構發展是有顯著的影響。在模擬較初期,雲凝結核數量濃度和颱風強度及降水較 為線性變化,但隨著降水系統發展,可能由於冰相微物理過程的非線性變化,使 得之後的颱風動力和結構方面同樣有較為複雜的變化。

關鍵字

颱風 ； 雲凝結核

並列摘要

The microphysics schemes have been applied to many numerical studies to
understand its influence to the track, intensity, structure and the precipitation type of typhoons. However, there are not many typhoon simulation studies on the CCN concentration. Recently, the research on the effect of the aerosol to the atmospheric environment as become more important, and many studies show that, the change of aerosol is indeed playing an important role in the microphysical processes.
Therefore in this research we used the WRF V3.3.1 to conduct a series of modeling study on Typhoon Nari(2001). We used the WDM6 microphysic scheme in this study, and we modified the initial CCN number concentration (by increasing 10 and 100 times), starting by the simplified of environmental condition (ocean), without the terrain.
From the simulation on pure ocean environment, we can found, if we increase the initial CCN number concentration, the typhoon will produce more precipitation particles in smaller sizes, relatively waker eyewall’s updrafts, and precipitation particle can be translated far away from the center of typhoon. As a result, the intensity of precipitation in eyewall area is weaker, the spatial distribution of each hydrometer also different; from the condensational heating rate vertical profile, the difference is obvious too. Thus we can infer that the difference on CCN concentration will greatly affect the tropical cyclone’s intensity and its structure evolution.

並列關鍵字

typhoon ； CCN ； cloud condensation nuclei

參考文獻

黃竹君, 2012:氣膠衝擊颱風之模擬 - 納莉颱風(2001), 台灣大學理學院大氣

Biggerstaff, Michael I., Robert A. Houze, 1993: Kinematics and Microphysics of the Transition Zone of the 10–11 June 1985 Squall Line. J. Atmos. Sci., 50, 3091-3110.

Cheng, C.-T., Wang, W.-C., and Chen, J.-P., 2007:A modelling study of aerosol impacts on cloud radiative properties. Q. J. R. Meteorol. Soc., 133, 283-279.

Cheng, C.-T., Wang, W.-C., and Chen, J.-P., 2010:Simulation of the effects of increasing cloud condensation nuclei on mixed-phase clouds and precipitation of a front system. Atmospheric Research., 96, 461-476.

Flossmann,A.I.,1998: Interaction of Aerosol Particles and Clouds, J. Atmos. Sci., 55, 879-887.