Analysis of Atmospheric Boundary Layer Characteristics during Strong Winter Wind Processes in Beijing

Based on meteorological gradient data and turbulent data from the 325-m observation tower of Institute of Atmospheric Physics, Chinese Academy of Sciences in Beijing, the meteorological condition and turbulent transfer characteristic were analyzed during two strong wind events occurred from 29 November to 5 December 2014. The magnitude and duration of the first strong wind event was larger than that of the second one. Strong vertical wind shear was found at the height below 100 meters above the ground surface, with the maximum value of 0.31 s^-1. The gust coefficient decreased with height, and a higher value of gust coefficient was found near the surface layer. The variation of gust intensity was similar to that of gust coefficient, and it also decreased with height below 100 meters. The turbulent structure was changed by the strong wind from the top to bottom. The average kinetic energy, turbulent kinetic energy and friction velocity all started to change from the top layer (280 m) and then increased rapidly. As a result of the remarkable difference in vertical wind gradient near the surface layer, the maximum turbulent intensity in the vertical direction occurred near the surface layer. The power spectra of all layers were higher in low frequency areas ( < 0.01 s^-1) during the strong wind event, and the power of all layers decreased after the strong wind event.