Wind Vertical Structure Observation and Difference Analysis of Large Range Heavy Rainfall with Warm Shear and Cold Shear Based on Wind Profiler Radar

Based on the wind profiler radar data of Liancheng county, Fujian province, the analysis of the heavy rainfall were caused by alternating warm shear and cold shear in Fujian province from 5 to 7 June 2018. Results show that: 1) the occurrence time of horizontal and vertical wind pulsation corresponds to the occurrence time of precipitation. The magnitude of horizontal wind pulsation and the height of horizontal wind pulsation are positively correlated with precipitation intensity, while the height of vertical wind pulsation is positively correlated with precipitation intensity. The strong horizontal and vertical wind pulsation are concentrated and high in warm shear potential, while the strong pulsation and vertical wind fluctuations are dispersed and low in cold shear potential. 2) Before precipitation or before precipitation increase, vertical wind shear of horizontal wind appears near 2 3 km altitude and propagates to the lower level. Vertical wind shear of horizontal wind at lower and upper levels increases to more than 10 m·s^-1 during precipitation; The vertical wind shear enhancement time of low-level horizontal wind under warm shear potential is 2-6 hours earlier than that of precipitation; the vertical wind shear enhancement time of low-level horizontal wind under cold shear potential is synchronized with precipitation. 3) Under the warm shear potential, the low-level jet index is relatively continuous and fluctuates greatly, corresponding to the intensity of precipitation is stronger, and the precipitation distribution is uneven; under the cold shear potential, the low-level jet index is more dispersed and fluctuates less, corresponding to the intensity of precipitation is weaker, and the precipitation distribution is uniform. The increase of low-level jet index is 1-4 hours ahead of precipitation. 4) In the warm shear precipitation stage, the SNR strong echo region appears at a higher altitude in the early stage of precipitation, and increases at the lower level when precipitation tends to weaken. In the cold shear precipitation stage, the SNR strong echo region maintains for a long time in the lower level.