关键词: 风向, 半固定沙垄, 风速, 古尔班通古特沙漠

Abstract: Field measurement of airflow velocity under different wind directions at five heights (0.2 m, 0.4 m, 0.6 m, 1 m and 2 m) over semi-fixed longitudinal dune was made in Gurbantunggut Desert. It was found that the airflow velocity increased over the windward slope and decreased over the lee slope, and both processes were deeply affected by wind direction. There exists a strong linear relationship between wind velocity and wind incidence angle. The magnification of wind velocity over the dune crest rises up with the incidence angles increase, while the proportions of wind velocity at 2 m high over lee slope to wind velocity at 2 m high over the dune crest reduce with the incidence angle's increase. The variation of airflow velocity was mainly controlled by the shape of dune when incidence angles were big, and that is mainly controlled by character of vegetation when incidence angles were small. No matter what direction the airflow come from, the variation amplitude of airflow velocity at 0.2 m high over dune surface was smaller than that at the other 4 heights. The wind speed profile in inter-dune was same with that over lower slope and both of them have a strong logarithm relationship with height, while the relationship does not exist over the upper slope and the dune crest. According to the wind speed profile over the upper of lee slope, a primarily conclusion is drew that the center of the whirlpool is at 0.4 m high from the sand surface.

Key words: wind direction, semi-fixed longitudinal dune, airflow velocity, Gurbantunggut Desert