新月形沙丘表面风速廓线与风沙流结构变异研究

在风沙地貌学中,跃移沙粒与风场的耦合作用下,其最直观的表现形式为风速廓线和风沙流结构的变异。通过对塔克拉玛干沙漠腹地新月形沙丘迎风坡坡脚、沙丘顶部、沙丘的两个兽角前端、沙丘背风坡坡脚5个典型部位的风速廓线和风沙流结构进行了实地观测,并与参照点（丘间粗沙地）的风速廓线和风沙流结构进行了对比。发现受地形扰动作用,沙丘背风坡坡脚处和沙丘的两个兽角前端的风速廓线形式均呈现非对数形式分布。除迎风坡坡脚处风沙流结构与参照点处相似之外,其余各个部位风沙流均表现出不同于参照点的结构形式。直接采用曲线拟合方法对风沙流结构函数进行拟合,并针对有明显分段现象的风沙流结构形式,采取分段拟合,并对造成风速廓线和风沙流结构变异的原因进行了讨论。

Variation of Wind Profile and Sand Flow Structure above Barchan Dune

Variation of wind profile and sand flow structure are the most visualized manifest in sand blown geomorphology under coupling of saltatory sand and wind field.Based on observation of wind profile and sand flow structure above a barchan dune in the Taklimakan Desert and comparison with those over a reference point(the flat ground between the longitudinal dunes),we found some variations of the wind profile and the wind-sand flow structure.Affected by perturbation of dune landform,the wind profiles above dune slip face and two horns’ nose are all manifested as non-logarithmic function form.Except for the foot of stoss slope,the sand flow structure above all other positions of the barchan dune are different to that over the reference point.Curve functions are fitted for the sand flow structures,and the segmental fitting is especialy used to fit those sand flow structure having segmental phenomenon.