关键词: 雷达回波特征, 径向速度, 风廓线, 冷垫, 中层辐合

Abstract:

The influencing system, characteristics of radar echoes and formation mechanism of two snowstorm weather processes caused by inverted-trough moving north and the Mongolia cyclone moving south in Liaoning were analyzed. The results indicated that there were significant differences about radar echoes for these two kinds of snowstorm weather. The zero speed line of radar presented straight through station and the cold air pad was thicker (1.5 km) according to the vertical wind profile (VWP) product during the inverted trough snowstorm process. A strong motivation and continuous cooling effect caused by strong cold air moving southward triggered the snowstorm, although low-level sinking cold air was not conducive to snowfall lasting, the vertical movement in middle level caused by southwest wind enhancement and radial convergence of north and south wind resulted in continuous snowfall and then the snowstorm occurred. During the inverted trough snowstorm process, it was a signal for forecasting and early warning five hours ahead of snowstorm that the cold pad was thickest and southwest wind velocity was maximum in the low and middle level. The zero speed line turned quickly from “S” to anti “S” during the Mongolia cyclone snowstorm, although the cold air pad was shallow according to the VWP, the southerly airflow maintained overall during the whole snowfall process, which caused the cyclone snowstorm.  The base velocity of radar presented rotation character under the influence of the low-level cyclone, which led to convergence of cold and warm air, then the vertical movement enhanced at the low-level. When the basic velocity presented overall northerly flow feature, the snowfall was near the end, which was different from the inverted trough snowstorm (the radial velocity presented consistent northerly wind feature.

Key words: radar echo characteristics, radial velocity, wind profiler, cold pad, middle-level convergence