SPATIAL AND TEMPORAL STATISTICAL CHARACTERISTICS OF THE WIND FIELD OF THUNDERSTORM OUTFLOWS BASED ON MEASURED DATA IN BEIJING URBAN AREA

The structural damage, property loss and personal injury caused by thunderstorm outflows often occur, and the understanding and study of their wind field characteristics are the basis of the design of structure resistance to thunderstorm outflows. The 70 thunderstorm outflow events identified based on the measured data of 325m high meteorological towers in Beijing urban area are statistically analyzed by applying the classical signal decomposition model of thunderstorm outflows. The research results show that thunderstorms occur frequently in summer, whose peak gust speeds mainly occur in the afternoon and evening of Beijing time and are more prone to occur in the northwest. When the peak wind speed occurs, the moving average wind speed profile presents a slight nose shape. The turbulence intensity and gust factor profiles are quite different from that of synoptic winds, and the statistical results of thunderstorm outflows are larger than the corresponding values of synoptic winds. The power spectral density of thunderstorm outflows is in good agreement with Von Karman model. The results of this study can provide a basis for the establishment of a unified model of the wind field of thunderstorm outflows and the design of structure resistance to thunderstorm outflows.