Characteristics of Atmospheric Boundary-Layer Structure and Turbulent Flux Transfer during a Strong Dust Storm Weather Process over Beijing Area
北京地区一次强沙尘暴过程的大气边界层结构和湍流通量输送特征

Based on the mean wind,temperature and humidity data and turbulent data observed at the Beijing 325 m Meteorological Tower,and the surface conventional meteorological data and sounding data collected at Beijing Meteorology Observatory,some characteristics of atmospheric boundary layer structure and turbulence transfer during the strong dust storm weather from 18 to 22 March 2002 was investigated.The results showed that,1) before the dust storm broke out,the mean wind speed was very slow and the temperature was comparatively high.And strong inversion layers existed in the upper atmospheric boundary layer(ABL).While after the dust storm broke out,the wind speed increased sharply and the temperature changed greatly.The temperature increased sharply in advance,and then decreased continuously.Consequently the inversion layer was rapidly destroyed.2) During the initial stages of the synoptic process,there were systematic upward flows at the 280 m height in the ABL,but systematic downward flows occurred at the heights of 47 m and 120 m during the synoptic process.The turbulence energy,the momentum transportation and the sensible heat transportation were increasing sharply.The turbulence energy and the fluxes of turbulent momentum and sensible heat collected at 120 m height was larger than those collected at the heights of 47 m and 280 m,perhaps which was caused by the local circumfluence of Beijing.3) In this dust storm process,the friction velocities collected at 47 m and 120 m heights were larger than the critical friction velocity of Beijing,consequently we got the conclusion that the local dust emission is one of the important source of dust particles of Beijing in this synoptic process.