Measurement and Modeling of Dust Emissions

在干旱和半干旱环境中，从游乐场、冲积扇和洗涤物等易受影响的表面排放粉尘大小的矿物颗粒(直径50微米)的情况仍然知之甚少。在某些风条件下，这些表面提供了一个重要的颗粒物来源，这些颗粒物可能导致高背景大气沙尘负荷，或者在某些情况下导致重大沙尘暴。沙尘可以被风的剪切力卷走，也可以通过沙粒跳跃运动的弹道冲击从地面喷射到气流中。尽管数据分散，但只考虑跳跃轰击和上风向沉积物无限供应的模型不能充分解释观测到的尘埃排放关系。PIS正在提出一项便携式风洞和塔式监测现场研究相结合的研究，以现场量化粗颗粒和细颗粒的水平和垂直通量，作为风参数和表面特征的函数。收集的数据库还将使他们能够测试文献中描述的三种粉尘排放模型的性能，其中包括粉尘排放和表面特征测量。这些知识对于修订或改进描述排放过程的模型是必不可少的。一个能够准确描述尘埃夹带率和垂直通量的模型对于预测风蚀造成的土壤流失和估计矿物气溶胶对大气的相对来源贡献是实际需要的。

9972960GilliesThe emissions of dust sized mineral particles (50 micron diameter) from susceptible surfaces such as playas, alluvial fans, and washes in arid and semi-arid environments remains poorly understood. Under certain wind conditions these surfaces provide a significant source of particulates that can result in high background atmospheric dust loadings, or in some cases, major dust storms. Dust can be entrained by the shearing force of the wind and also ejected from the surface into the air stream by the ballistic impact of sand grains moving in saltation. Models that consider only saltation bombardment and an unlimited supply of upwind sediment do not adequately explain observed dust emission relationships, data scatter notwithstanding. PIs are proposing a combined portable wind tunnel and tower monitoring field study to quantify in situ the horizontal and vertical fluxes of coarse and fine particles as a function of wind parameters and surface characteristics. The collected database will also allow them to test the performance of three dust emission models that have been described in the literature with dust emission and surface characterization measurements. This knowledge is essential for revising or improving models that describe the emission process. A model that can accurately characterize dust entrainment rates and vertical flux is a practical necessity for predicting soil loss due to wind erosion and for estimating relative source contributions of mineral aerosols to the atmosphere.