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

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.