Analyzing the vertical wind shear characteristic of a severe rainfall using wind-profile radar data

In the article, we analyze the occurrence and development of the intensive rainfall along Haihe area on 21 July 2012 using the combination of data from 5 wind profiler radars, Doppler weather radar network and weather data from auto-weather stations along Haihe area. The study reveals that the intensive rainfall carries obvious characteristics of the mid-range weather systems in which the occurrence of rainfall is often in the gradient zone of the dew point temperature. The low jet index change is indicative to the peak value in the short-term intensive rainfall, i.e., its fast increase means the beginning of the intensive rainfall. The vertical wind shear is of reference value to the short-term intensive rainfall. That is, prior to the rainfall, the wind speed and wind shear begin to increase at middle and low levels (2 500- 3 000 m), followed by the strong wind spread to the lower level (1 000 m). The increase of the wind shear gradient predicts the beginning of the short-term intensive rainfall. When the wind speed at low level (1 000-1 500 m) reduces quickly as that in the higher level, the intensive rainfall weakens till its stop. The above features are applicable in forecasting and decision making for intensive rainfall.