石羊河流域下游青土湖近地层风尘分布特征

发布时间：2018-01-14 12:00

本文关键词：石羊河流域下游青土湖近地层风尘分布特征　出处：《干旱区地理》2016年06期 　论文类型：期刊论文

【摘要】：青土湖属于极端干旱区典型的干涸盐湖,盐尘中含有密度很高、粒径极细的盐碱粉尘,严重污染空气,危害地表植被,威胁干旱区绿洲生态安全。利用建立在青土湖的近地层0~50 m沙尘观测系统近2 a监测的数据,对近地层0~50 m盐尘的分布规律及风速的变化特征进行研究。结果表明:(1)风速在0~50 m垂直梯度的分布符合经典的风速随高度的增加而增大的基本特征,廓线方程遵循幂函数关系;年内月平均风速最大为5月,最小为11月,且表现出明显的季节变化特征,春、夏季平均风速大于秋、冬季;近地层18~2 m内风切变指数较大,且春、夏季风切变指数相对较小;34~28 m、50~34 m内风切变指数变化较小,且四季变化不明显。(2)盐碱沙尘水平通量的空间分布随高度的增加而增加,在垂直高度上遵循幂函数变化规律;受下垫面梭梭林的影响,在6 m高度处有一个较为明显的增加。(3)沙尘水平通量与风速之间呈现出幂函数关系,且呈明显的正相关关系。
[Abstract]:Qingtu Lake is a typical dry salt lake in extreme arid area. Salt dust contains very high density and fine size of salt and alkali dust, which seriously pollutes the air and endangers the surface vegetation. It is a threat to the ecological safety of oasis in arid area. The monitoring data of the near 2 years monitoring system of 0 ~ (50 m) sand dust built on Qingtu Lake are used. The distribution law of 50 m salt dust and the variation characteristics of wind speed are studied. The results show that: 1). The distribution of the vertical gradient of wind speed at 0 ~ 50 m accords with the basic characteristics of the classical wind speed increasing with the increase of height. The profile equation follows the power function relation; The monthly mean wind speed in the year was the largest in May and the smallest in November, and showed obvious seasonal variation characteristics. The average wind speed in spring and summer was greater than that in autumn and winter. The wind shear index is relatively small in spring and summer. The change of wind shear index is relatively small, and the change of seasonal change is not obvious. (2) the spatial distribution of saline-alkali sand dust level flux increases with the increase of height. The law of power function is obeyed in the vertical height. Under the influence of Haloxylon ammodendron forest on the underlying surface, there was an obvious increase in the sand dust level flux at 6 m height. There was a power function relationship between the sand dust level flux and the wind speed, and there was an obvious positive correlation between the sand dust level flux and the wind speed.
【作者单位】：甘肃省治沙研究所;甘肃民勤荒漠草地生态系统国家野外科学观测研究站;甘肃省荒漠化与风沙灾害防治国家重点实验室(培育基地);
【基金】：国家林业公益性行业科研专项(201404306) 甘肃省青年基金计划项目(145RJYA270)
【分类号】：X513
【正文快照】： 青土湖位于石羊河流域下游,属于荒漠区干涸湖泊,为盐碱化荒漠[1]。湖底盐碱化非常严重,干涸湖底在风力的作用下,细小的盐碱粉尘被卷入空气中,为沙尘暴和浮尘天气的形成提供物源。大量的含盐粘性沉积物被大风带至下风向的地区,大气气溶胶中颗粒物浓度急剧增加,盐碱沙尘中可溶性

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