若干风蚀粉尘释放模型述评

Review on Progress in Modeling Dust Emission Caused by Wind Erosion

粉尘气溶胶对大气、陆地和海洋多方面的影响促进了粉尘释放的模拟研究。Gillette和美国EPA的粉尘释放模型相对地比较简单,主要考虑了摩阻速度和土壤质地对粉尘释放的影响,没有考虑粉尘释放过程的微观机制;邵亚平和Alfaro等人的DPM粉尘释放模型都通过土壤粒度分布、粗糙度和起动摩阻速度等参数表达了地表特征对粉尘释放的影响,且都描述了粉尘释放的微观机制。20多年来粉尘释放的模拟研究取得了重要进展,主要表现在通过室内和野外实验证实了粉尘释放的主要机制为跃移颗粒的冲击,并分别从粉尘的结合能与跃移颗粒动能及跃移颗粒产生的弹坑体积角度来描述这个微观机制。然而所有的模拟工作只是从某一方面反映了粉尘释放过程,对粉尘释放机制还没有完全了解清楚,特别的是目前关于粉尘结合能研究还有很大的不确定性,这也是粉尘释放模型需要改进的地方。

Dust aerosols play multiple roles in the interface of atmosphere, continent and ocean, which promote the developments of variety of dust emission models. The models proposed respectively by Gillette et al and US EPA are too simple in that only the two factors of friction velocity and soil texture are taken into account, while the mechanism of dust emission by wind erosion cannot be expressed. The model of Shao et al and DPM model of Alfaro et al, illustrate the effect of surface features on wind erosion in terms of the parameters of soil size distribution, roughness length, threshold friction velocity and moisture, and also describe the mechanism of dust emission on the basis of binding energies of aggregates and crater volume of saltating aggregates. It has been an obvious progress in simulating dust emission that sandblasting mechanism of dust entrainment is proposed and verified through wind tunnel experiment and field observation for the last two decades. Nevertheless, all the models for dust emission are far from perfect due to limited knowledge of dust entrainment mechanisms, especially more uncertainties existed in modeling binding energies of aggregates, which should be exactly modified in the future.