Intermittent aeolian saltation over a gobi surface: threshold, saltation layer height, and high-frequency variability
Intermittent aeolian saltation over a gobi surface: threshold, saltation layer height, and high-frequency variability
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戈壁表面间歇性风盐跃动：阈值、盐跃层高度和高频变化
DOI：
10.1029/2019jf005329
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发表时间：
2020
影响因子：
3.9
通讯作者：
Wang Junzhan
中科院分区：
文献类型：
--
作者：
Tan Lihai;An Zhishan;Zhang Kai;Qu Jianjun;Han Qingjie;Wang Junzhan
戈壁是亚洲的一种沙漠路面，其上的风成跃移产生大气尘埃。然而，对戈壁风沙跃移的高频行为仍然知之甚少。在这项研究中，耦合高频观测三维（3‐D）风速（U）和跃移粒子计数率在垂直阵列的Sensit传感器在中国新疆南部米兰县的戈壁地区进行。结果表明，戈壁风沙跃移具有间歇性，跃移强度受相对风强度的控制，与沙面的跃移强度一致。临界风速（Ut）随传输活动参数（AP）的增大呈指数下降，当AP值达到0.7时，Ut显著下降;而对于沙面，在AP值为0 ~ 1的整个范围内，Ut呈线性下降趋势。跃移颗粒在戈壁表面呈0.08-0.30 m的层状分布，平均值为0.20 ± 0.04 m，明显大于沙面。戈壁表面瞬时输沙率（Q）与U的相关性较差，滞后Q 2s可改善Q与U的相关性。跃移颗粒与坚硬复杂结构的戈壁床和松软变形的砂床的碰撞机制有很大的不同，从而导致了戈壁和砂面的风成跃移差异。
Gobi is a type of desert pavement in Asia over which aeolian saltation generates atmospheric dust. However, the high‐frequency behavior of aeolian saltation over gobi is still poorly understood. In this study, coupled high‐frequency observations of three‐dimensional (3‐D) wind speed (U) and saltation particle count rate in a vertical array of Sensit sensors were performed in a gobi region of Milan County, southern Xinjiang, China. The results revealed that aeolian saltation over a gobi surface exhibited an intermittent phenomenon, and the level of the intermittency was governed by the relative wind strength (s), which is consistent with that of sand surfaces. The threshold wind speed (Ut) decreased exponentially with increasing transport activity parameter (AP), and a prominent decrease inUtwas examined when the AP values reached 0.7; comparatively, for sand surfaces, a linearly declining trend occurred over the whole AP range of 0–1. The saltating particles over the gobi surface were distributed in layers of 0.08–0.30 m with an average value of 0.20 ± 0.04 m, which was significantly larger than that of sand surfaces. The relationship between the instantaneous sand transport rate (Q) andUover the gobi surface was also relatively poor and could be improved by laggingQby 2 s. The mechanism for the collision between saltating particles and the gobi bed, which is rigid and complex in texture, was significantly different from that of the soft and deforming sand bed, causing the difference in aeolian saltation between gobi and sand surfaces.