Automatic identification of ground thunderstorm gale based on the radar mosaic 3D data

Based on the radar mosaic 3D data and ground automatic wind data, the six main radar identification indices of ground thunderstorm gale are statistically analyzed: storm maximum reflectivity, storm maximum vertical integrated liquid water content (VIL), time change rate of vertical integrated liquid water, dropping height of the storm maximum reflectivity, storm body movement speed and VIL density. According to the correlation of the radar identification index with surface wind, membership functions and weighting coefficients of each identification index are given. Adopting the unequal weighting method, an identification method of thunderstorm gale based on the fuzzy-logical principle is established. It has been distingished into three levels according to the probabilities in the paper: the probability of the occurrence of thunderstorm gale is low when the criterion used in the method is less than 0.3; the probability of gale is high when the criterion is between 0.3-0.5; the probability leads to being very high when the criterion rises to more than 0.5. Two typical cases in Hebei Province are analyzed and tested, one caused by a line thunderstorm which happened on 21 June 2012, and the other caused by an isolated single-cell storm which happened on 23 July 2009. The results show that the tracking effect of this method to identified storm is good, the identified wind range is consistent with the real one, and the hit rate, the false alarm rate and the critical success index reaches 81.8%, 25% and 64.3%, respectively. It also shows that the automatic identification established by the fuzzy-logic principle is feasible.