云特征参数与降水相关性的研究

摘要

Based on the cloud structural characteristic parameters retrieved by FY2C satellite and radio sounding data,combined with precipitation on ground,the relationship between cloud parameters（ including cloud top height,optical thickness,particle effective radius,depth of cloud,etc） and precipitation was studied. The relationship between frequency distribution of cloud parameters and precipitation during stratiform cloud precipitation process and convective cloud precipitation process was researched further. Results show that precipitation is usually easy on the ground when cloud depth is thicker than 5 km,cloud base is low,and effective cloud particle radius is large. When cloud top height is greater than 10 km,optical thickness exceeds 20,and there is no or very thin interlayer in cloud,the surface precipitation intensity is usually more than 1 mm/h. For the stratiform cloud precipitation,if cloud optical thickness value exceeds 17,the probability of precipitation on ground will be higher. With the increase of optical thickness, surface rainfall intensity shows an increase tendency. For the convective cloud precipitation,there is a good correlation between cloud top height and optical thickness. While optical thickness value exceeds 17and cloud top is higher than 7 km,the probability of precipitation on the ground is greater. If the cloud optical thickness exceeds 20,surface precipitation intensity will increase significantly. Both the precipitation probability of stratiform cloud and convective cloud increases with cloud top height and optical thickness. The probability of precipitation is more related to optical thickness. Clouds of optical thickness value less than 10 are difficult to precipitate. If cloud optical thickness exceeds 20,precipitation probability of stratiform clouds and convective clouds will increase evidently. Comprehensive analysis of cloud top height, cloud thickness,optical thickness and other cloud parameters could be more effective to determine precipitation region and intensity on the ground.%利用FY2C卫星和探空反演得到的云结构特征参数,结合地面降水,研究了云顶高度、光学厚度、云粒子有效半径和云厚度等云结构参数与降水的关系,并分类研究了层状云和对流云在不同降水强度情况下,云参数的频数分布规律及其与降水的关系。结果表明：通常云厚大于5km、云底较低、云粒子有效半径较大时,地面易出现降水,若云顶高于10km、云光学厚度大于20且云中无夹层或夹层稀薄时,地面雨强多大于1mm/h;对于层状云降水,当云光学厚度大于17时,地面出现降水的概率较大,随光学厚度值增加,地面雨强呈增大趋势;对于对流云降水,云顶高度和光学厚度相关性较好,云光学厚度大于17且云顶高于7km时,地面出现降水的概率较大,当光学厚度大于20时,地面雨强明显增大;层状云和对流云的降水概率均随云顶高度和光学厚度的增加而增大,降水概率与云光学厚度的相关性更为密切,光学厚度小于10的云很难产生降水,而云光学厚度大于20时,层状云和对流云的降水概率都会显著增加;综合云体的高度、厚度和云光学厚度等云参量的组合特征,对分析判断地面降水落区和降水强度更加有效。