一次暴雨过程中云微物理特征的卫星反演分析

Analyses of satellite retrieval microphysical properties of a rainstorm in the northern part of Shaanxi.

  • 摘要: 利用卫星反演技术和云微物理分析方法,以陕北2006年7月2日发生的暴雨过程为例,反演了云顶粒子有效半径(Re)、云顶温度(T)等云物理特征参数,通过卫星不同时次对暴雨云团的探测资料,分析了暴雨发展过程。暴雨云团表现为多单体特征,发展旺盛期对流单体的数量明显增加、云团尺度大幅增加。根据暴雨云系中的对流云、层云、过冷水云、低云(未被高云遮挡住)4种类型,分别选择了9个代表区,用于分析这次暴雨过程中不同类型云的物理特征和垂直结构。结果表明:此次暴雨云团由多种高度的云组成,低云高度较低,温度较高,云顶在0—-10 ℃;层云高度略高,T为-10—-20 ℃, Re为10—20 μm,并含有连片分布的过冷水云(Re为10 μm左右);高度最高的云为对流云,镶嵌在系统性层云中或在其上发展, T最低达到-80℃左右。从云底至0℃层存在一个较厚的凝结增长带, R e为5—10 μm;0—-10 ℃层存在一个碰并增长带,Re从13—15 μm增长到20—25 μm,但其厚度小于凝结增长带;T<-10 ℃层以上存在一个深厚的冰相增长带,表明在对流云团的发展成熟期,冰相增长过程为优势云物理过程。随着云的逐渐发展,混合相增长带由厚变薄,冰化增长带增厚,晶化温度升高、高度降低,表明在对流云团发展到成熟的过程中,冰化增长带在下传,云中冰化增长过程向下传递明显。

     

    Abstract: With the polar-orbit satellite retrieval methodologies developed by D. Rosenfeld, taking the rainstorm occurred in the northern part of Shaanxi on 2 July 2006 as an example, the particle effective radii (R e) and the temperature at the cloud top were retrieved. The developing process of convective cloud clusters in this rainstorm was analyzed by comparing with their size, the temperature and the number of convective cells based on the two different satellite observations for a same cloud cluster. Convective cloud clusters of the rainstorm were characterized by coexistence of multiple convective cells with their numbers and sizes increased greatly for the fully developing cloud clusters. According to the different cloud types of convective clouds, layer clouds, super-cooled water clouds and low level clouds (not covered by high clouds) occurred in this rainstorm, 9 study areas representing the 4 typical cloud types were chosen to analyze the microphysical properties and vertical structure via the temperature versus effective radii (T Re) relation. The analyses show that the cloud cluster caused the rainstorm were composed of various clouds of different heights. Among them the height of low level clouds was rather low with their cloud top temperature rather high, ranging from 0 to -10℃. The height of layer clouds was higher than that of low level clouds with their cloud top temperature ranging from -10 to -20℃, and their Re varying from 10 to 20 μm. There existed some sheets of super cooled water clouds among the layer clouds with Re of about 10 μm. The clouds of larger height were convective ones which are mosaicked in or developing above the systematic layer clouds with its minimum temperature reached -80℃. There existed a deep zone of diffusional droplet growth from the cloud base to the level of 0℃ with their Re of about 5-10 μm, and also a thinner zone of droplet coalescence growth from 0 to -10℃ levels with Re of 13-15 μm to 20-25 μm. The zone with both the mixed phase and glaciation zones covered was very great, which suggested that the predominant microphysical process was ice growth during the development of convective cloud clusters. With the gradual development of these clouds, the mixed phase zone become thinner and the ice phase zone become thicker with the crystallization temperature raising and the level lowering, suggesting that the glaciation zone propagated down with the glaciation processes extended dramatically to the lower levels from the development to the mature stage.

     

/

返回文章
返回