Particle Dry Deposition From the Ambient Atmosphere: The Role of Particle-Surface Interactions

空气中的颗粒物在维持 地球的能量平衡，维持生态系统和影响 化学物种的全球循环。 不幸的是我们的 了解影响这些颗粒的过程，从 排放到他们的最终命运，是远远没有完成。 一 一个特别的缺陷是我们对粒子的知识有限 通过干沉积从大气中去除。 该项目的总体目标是确定最 影响气溶胶干沉降的重要因素 粒子，侧重于粒子和 植被的表面。 具体目标有三个： 1)开发改进的数学公式， 粒子-表面相互作用的机制，2）验证这些 配方通过风洞试验，和3）应用 通过开发和验证一种 冠层内沉积模型 目标1将通过以下方式实现： 改进湍流领域的现有配方 通过粘性底层的静电传输 吸引力和再悬浮。 目标2将通过以下方式实现： 在风中进行沉积和再夹带测量 使用可测量的单分散铀酸颗粒的隧道 通过荧光。 最后，目标3将通过以下方式实现： 开发一个模型，将空气中的浓度与 植被元素的冠层和几何形状被用作 模型输入 环境化学物质干沉积测量 已知大小分布的物种将允许验证 该模型 这项研究的结果将使一个更好的 了解最重要的影响过程 颗粒干沉积到自然表面上。 这反过来又 将产生更准确的干沉降预测， 大气传输模型的组成部分。

Airborne particles play a vital role in maintaining the earth's energy balance, sustaining ecosystems and influencing global cycles of chemical species. Unfortunately, our understanding of the processes affecting these particles, from emissions to their ultimate fate, is far from complete. A particular deficiency concerns our limited knowledge of particle removal from the atmosphere by dry deposition. The overall goal of this project is to determine the most important factors influencing dry deposition of airborne particles, focusing on interactions between particles and the surface of vegetation. There are three specific objectives: 1) to develop improved mathematical formulations for several mechanisms of particle-surface interaction, 2) to verify these formulations through wind tunnel tests, and 3) to apply the formulations to field conditions by developing and verifying an in-canopy deposition model. Objective 1 will be achieved by improving existing formulations in the areas of turbulent transport through the viscous sublayer, electrostatic attractions, and resuspension. Objective 2 will be achieved by conducting deposition and reentrainment measurements in a wind tunnel using monodisperse uranine particles that can be measured by fluorescence. Finally, objective 3 will be achieved by developing a model that relates airborne concentrations within the canopy and geometry of the vegetation elements are used as model inputs. Measurement of dry deposition of ambient chemical species with known size distributions will allow verification of the model. The results of this study will enable a better understanding of the most important processes influencing particle dry deposition onto natural surfaces. This, in turn, will yield more accurate prediction of dry deposition as a component of atmospheric transport models.