Chemical Heterogeneity Among Fog Drop Populations and Its Influence on Aerosol Processing by Fogs

本研究项目包括实地研究雾滴种群之间的化学异质性以及这种异质性对气溶胶和微量气体处理的影响。该项目包括首次部署两个新的云/雾采样器，旨在提供更好的液滴组成分辨率，作为液滴大小的函数。这些采样器在过冷云中提供3级液滴收集，在暖云和雾中提供5级收集。新的多阶段收集器将用于在两个主要的野外活动中测量水滴大小分解的雾成分：2000/01冬季在圣华金河谷进行的密集的加州区域PM10/PM2.5空气质量研究（CRPAQS）期间，以及2001/02冬季在丹佛布朗云进行的雾对气溶胶处理的研究。这两项研究的结果将在理解雾滴组成如何在雾滴大小光谱上变化以及这种变化对气溶胶形成（通过气体吸收和水硫氧化）和去除（通过雾滴沉积）的影响方面取得相当大的进展。CRPAQS研究也将提供第一个很好的机会来测试大小分辨雾化学模型的能力，以准确预测雾的大小依赖的化学成分。一种新的两级不锈钢雾采样器也将被开发并部署在两个现场作业中。该仪器将首次提供有关有机碳在液滴大小谱上的分布及其对城市雾通过清除和沉积净化大气中有机气溶胶颗粒的能力的影响的可靠信息。

This research project consists of field stidues to examine the chemical heterogeneity among fog drop populations and the effects this heterogeneity exerts on aerosol and trace gas processing. The project involves the first deployments of two new cloud/fog samplers designed to provide better resolution of drop composition as a function of drop size. These samplers provide 3-stage droplet collection in supercooled clouds and 5-stage collection in warm clouds and fogs. The new multi-stage collectors will be deployed to measure drop size-resolved fog composition in two major field campaigns: in winter 2000/01 during the California Regional PM10/PM2.5 Air Quality Study (CRPAQS) intensive in the San Joaquin Valley and in winter 2001/02 in a study of aerosol processing by fogs in Denver's Brown Cloud. Results from both studies will represent a considerable advance in understanding of how fog drop composition varies across the drop size spectrum and the influence of this variation on aerosol formation (via gas uptake and aqueous sulfur oxidation) and removal (via drop deposition). The CRPAQS study will also provide the first good opportunity to test the ability of size-resolved fog chemistry models to accurately predict the size-dependent chemical composition of fogs. A new 2-stage stainless steel fog sampler will also be developed and deployed in both field campaigns. This instrument will provide the first reliable information about the distribution of organic carbon across the drop size spectrum and its influence on the ability of urban fogs to cleanse the atmosphere of organic aerosol particles by scavenging and deposition.