Gr ain- size Var iation on a Tr ansver se Dune and Response to Wind Dir ection Changes on Southern Edge of Mu Us Deser t
毛乌素沙地南缘横向沙丘粒度分布及其对风向变化的响应

The transect data of morphology and grain-size samples has been obtained from a transverse dune with 8m high and 48m long in the south edge of Mu Us Sandy Land in the period of wind direction transitions. The results show that there exist temporal changes in grain-size and its spatial pattern on transverse dune responding to different wind directions and magnitudes. These changes are more obvious in the creastal zone of dune with more sand activity. Great temporal changes take place in the grain size frequency distribution, mean grain size and skewness among the grain-size parameters. This suggests that these parameters are most susceptive to the wind, and so their changes can be used to explain the difference of dunes in the influence of different wind. The evidences of the wind direction, dune morphology and grain-size characteristics identified there not only have seasonal but daily changes in grain-size patterns on the dune when wind direction changes. It further confirms the conclusion that the time of sampling is as important as the site.