关键词: 阵风锋, 强对流, 风廓线雷达, 信噪比, 螺旋度

Abstract: Based on conventional observation data, National Centers for Environmental Prediction (NCEP) reanalysis data, Doppler weather radar and wind profile radar data, as well as secondary development product data, the weather process of thunderstorm gale and short-time heavy precipitation triggered by a gust front in Wuhu area, China, on July 19, 2021 was analyzed. The results show that: (1) The radial velocity field near the gust front has obvious convergence characteristics. When the gust front meets a favorable environmental field during its movement, it can trigger the formation of new thunderstorm cells. (2) The wind profile data products can reflect the vertical atmospheric motion before and after the passage of the gust front. There are weak rising and sinking motions at the same time in the atmosphere during the pre-frontal stage. In the early stage of the front, the sinking cold air of the thunderstorm parent causes the atmospheric subsidence to be the main movement, and the minimum height of the shear layer of wind field decreases first and then increases, and the thickness of the shear layer becomes thinner. During the transit and the post-frontal phases, there are both rising and sinking movements. (3) The signal-to-noise ratio (SNR) can directly reflect the beginning and end of precipitation and the changing characteristics of rain intensity during severe convective weather. As convective precipitation is affected by precipitation particles and turbulence, its SNR increases significantly 10 minutes before precipitation begins. After the beginning of precipitation, the SNR of convective precipitation is larger than that of stable precipitation, generally maintaining between 50 and 65 db, and between 55 and 70 db when the rain intensity is maximum. (4) The peak time of helicity (SRH), calculated by the secondary development of wind profile data, is 1–2 hours earlier than that of rain intensity maximum, which can be used as a reference factor to predict the occurrence time of heavy precipitation.

Key words: gust front, strong convection, wind profile radar, signal to noise ratio, helicity