关键词: 粗糙度, 临界起沙速度, 临界摩擦速度, 摩擦速度

Abstract: Dust storms are disastrous weather phenomena frequently occurring in spring (March-April-May) in North China. Since 2000, the dust weather has frequently occurred in this region, resulting in serious environmental problems and disruption of social & economic activities. In recent years, due to the impact of desertification in China, dust storms appear to have aggravated. Besides, domestic and foreign scholars have noticed that the aerosol in atmosphere has recently been increasing due to wind erosion and it has become a hot topic in the research field. What is more, wind erosion, a very complex physical process, acts as a key progress of basic research on aerosol in the atmosphere. As to wind erosion, theoretical and experimental studies by the domestic & foreign have established a lot of mathematical models on dust emission. A case in point is the research in Guaizi Lake. Guaizi Lake, located in the northern margin of Badan Jaran Desert, is one of Chinese major centers of dust storms. Apart from that, as the north path of Chinese dust storms, Guaizi Lake usually raised dust in the region, which may affect the whole northern China. With the limitation of natural conditions and experimental equipment, it is difficult to do experimental research in Chinese major centers of dust storms for a quite long time. Fortunately, the “National Scientific and Technological Support Project” advocated establishing the Guaizi Lake wind observation site in order to further study the dust storms. The experimental system consists of a 2m high meteorological tower, a piezoelectric saltation sensor (Sensit) and a big Spring Number Eight (BSNE) sampler station. The piezoelectric saltation sensor (Sensit) can continuously record the occurrence and intensity of saltating particles, while the BSNE station consists of five BSNE samplers with the lowest sampler at 0.05 m and the highest sampler at 2.0 m above the soil surface, thus getting the monitoring data about the dust storms. The research on dust storms was strengthened by observations, several characteristics of sand movement were studied，calculated by using the classical formula and analysing the records of the site actual measurement as well. The conclusions are as follows ：the critical sandmoving velocity at 2 m height is 4.55 m/s; the critical friction velocity is about 0.318 m/s; the average surface roughness is about 9.42 mm; the sandmoving average friction speed of April 5, 2011 is about 0.371 85 m/s; the friction velocity is positively correlated with the wind speed . The results indicate as follows: the threshold of sandmoving wind velocity, the roughness and the critical friction velocity are extremely small, which is one of the main reasons of sanddrifting activities. To sum up, it is very significant to calculate the parameters mentioned above for the sand storm control in Guaizi Lake area and this study fills the gap in some related parameters about windsand movement in this area.

Key words: roughness, critical friction velocity, friction velocity