大氣中的懸浮微粒可以吸收水氣或其他氣體而凝結成長，稱為凝結核，能夠在成雲過程中促使雲滴生成的稱為雲凝結核，而能促使冰晶形成的則為冰核。在近年來，在雲物理過程中關於氣溶膠在雲和降水過程中的作用及影響是受到許多人的關注及討論的。
本研究利用中尺度氣象模式MM5進行氣溶膠的敏感度實驗。在雲微物理過程選用CLR 參數法，此參數法是將Chen and Liu（2004）針對暖雲所提出的C&L暖雲參數法與Reisner 2參數法相結合。希望能瞭解懸浮微粒的數量濃度變化對於降水的影響。
本研究選定了兩個梅雨季節的降雨個案，一為2008年6月5日典型的鋒面降水個案，另一個為2008年6月16日的西南氣流降水個案，進行模擬懸浮微粒對於梅雨鋒面降水系統之敏感度實驗。將模式初始場的懸浮微粒數量濃度 以Whitby(1978)所提出的平均型背景場之懸浮微粒數量濃度為控制組，分別增加以及減少懸浮微粒之數量濃度，並比對其模式模擬結果。懸浮微粒數量濃度的變化對於個案的地面降水、雷達回波強度、水相粒子的變化都有其影響性。並對個案中系統的發展時間有顯著的影響。

In atmosphere, suspended particulates may absorb the moisture or the other gas to condensation grow, called condensation nucleus. Cloud condensation nucleus can make cloud drops grow, and ice nucleus can make the ice crystal grow. The effect of aerosols on clouds and precipitation is a hot topic and difficult problems in cloud microphysics researches in recent years.
In this endeavor, sensitivity of cold cloud microphysical processes to aerosols has been tested. A non-hydrostatic mesoscale cloud model (MM5)has been used for this simulation. And we used CLR cloud microphysics parameter scheme which couple the warm-cloud parameterization of Chen and Liu(2004) with the ice-phase cloud parameterization of Reisner et al. (1998).In order to understand the effect of number concentration of suspended particulates.
There are two Mei-Yu front cases are chose in this study , one is on June 5, 2008, the typical Mei-Yu frontal precipitation case, and another is on June 16, 2008 southwesterly flow precipitation case. Using the average background aerosols number concentration field which proposed by Whitby(1978) to be a control run, and change the number concentration of aerosols. The simulation results indicated that different concentration of aerosols affect precipitation, radar echoes, hydrometeors’ mixing ratio, and the develop time of the systems.

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