裸露农田近地表风速脉动特征  

Characteristics of wind speed pulsation above a bare farmland surface

作　　者：张慧 张春来 刘欣宇 代豫杰 岑松勃 沈亚萍 Zhang Hui;Zhang Chunlai;Liu Xinyu;Dai Yujie;Cen Songbo;Shen Yaping(State Key Laboratory of Earth Surface Processes and Resource Ecology/MOE Engineering Research Center of Desertification and Blown-sand Control,Faculty of Geographical Science,Beijing Normal University,Beijing 100875,China)

机构地区：[1]北京师范大学地理科学学部地表过程与资源生态国家重点实验室/防沙治沙教育部工程研究中心,北京100875

出　　处：《中国沙漠》2020年第5期57-64,共8页Journal of Desert Research

基　　金：国家自然科学基金项目(41630747)。

摘　　要：利用河北坝上地区裸露农田近地层风速的连续观测资料,分析了净风与风沙环境下近地表风速脉动特征。结果表明:地表风速脉动强度(uv)随平均风速的增加而增大,净风环境下脉动强度随风速的增大比风沙环境增加的更快,反映了运动沙粒对风速脉动过程具有一定的抑制作用。湍流度随平均风速的变化呈现幂函数递减趋势,净风环境的湍流度大于风沙环境。脉动风速的分布范围、概率分布集中性以及脉动强度与风速统计时距(Δt)有关。时距越小,脉动风速的分布范围越小,概率分布越集中。uvmax/uv随时距增大表现出先迅速减小(Δt <5 min)后趋于稳定(Δt> 5 min)的变化趋势,<5 min的风速时距能较好地反映风速脉动特性。考虑到风速数据获取的可行性,在计算输沙率时,采用1~5 min时距的风速统计资料较为合理。Based on the continuous observation of wind speed above a bare farmland surface in the Bashang regions,characteristics of wind speed pulsation in the net wind and blown sand environment were analyzed. The-results show that the pulsation intensity(uv)is positively related to the average wind speed(u),and uv increases with u faster in the net wind than in the blown sand environment,indicating that the blown sand has a inhibitory effect on the wind speed pulsation. The change of turbulence intensity(g)with the average wind speed shows a decreasing trend in power law. The distribution range of wind speed pulsation and the concentration of its probability distribution are related to the time interval(Δt)for averaging wind speed. The smaller the time interval,the smaller the distribution range of pulsating speed and the more concentrated the probability distribution. As Δt-increases,uvmax/uv shows a trend of rapid decrease when Δt < 5 min and tends to be stable when Δt > 5 min,implying that wind data averaged with Δt < 5 min can reflect the characteristics of wind pulsation well. Considering the feasibility in data access,it is reasonable to use the wind speed data of 1-5 min time interval in calculating the sediment transport rate which is influenced by wind pulsation.

关 键 词：农田 风速脉动 湍流度 平均风速的时距 

分 类 号：X169[环境科学与工程—环境科学]