Individual-particle Aerosol Experiments in the Marine Troposphere

海洋边界层和自由对流层中的气溶胶粒子直接通过辐射后向散射和间接作为云凝结核影响全球太阳辐射平衡。 该项目将使用单个粒子方法来研究影响气溶胶粒子大小分布、浓度和化学成分的对流层过程。 主要重点将放在南太平洋偏远地区的海洋边界层和覆盖该层的层积云。 分析将使用自动电子束仪器，特别是新的扫描电子显微镜进行。 该研究小组在过去十年中开发的方法允许通过定量测定组成和形态来研究大量颗粒。 这项研究的数据将用于解决大气气溶胶研究中的当前问题，包括（a）海洋气溶胶粒子的产生、分离和反应;（B）天然非海盐硫酸盐粒子的产生;（c）海洋层积云中液滴和间隙空气之间气溶胶粒子的分配;（d）气溶胶粒子的云处理;（e）气溶胶粒子的云处理;（f）气溶胶粒子的云处理。和（e）海洋对流层远距离迁移期间气溶胶的演变。 作为一项辅助任务，将使用透射电子显微镜，通过成像和化学分析，以高空间分辨率研究复杂的超微米至亚微米颗粒的结构和组成。 透射电子显微镜还可以检查亚微米单个颗粒中涉及硝酸盐和氨的反应。 这些拟议的研究加在一起，将提供关于海洋对流层中出现的影响辐射后向散射和云的微物理特性的各种粒子类型的精细数据。

Aerosol particles in the marine boundary layer and free troposphere impact the global solar radiation balance, both directly through radiation backscatter and indirectly as cloud condensation nuclei. This project will use individual-particle methods to examine tropospheric processes that affect aerosol- particle size distribution, concentrations, and chemical compositions. Primary focus will be on the marine boundary layer and stratocumulus clouds that cap that layer in the remote areas of the South Pacific. Analyses will be performed with automated electron-beam instruments, especially the new scanning electron microscope. Methods developed by this research group over the past decade allow the study of large numbers of particles by quantitative determination of composition and morphology. The data from this research will be used to address current issues in atmospheric aerosol research, including (a) the generation, fractionation, and reaction of marine aerosol particles; (b) production of natural, non-sea-salt sulfate particles; (c) partitioning of aerosol particles between droplets and interstitial air in marine stratocumulus clouds; (d) cloud processing of aerosol particles; and (e) evolution of aerosols during long-range transport in the marine troposphere. As a ancillary task, the structure and composition of complex supermicron to submicron particles will be investigated a high spatial resolutions using transmission electron microscopy, both by imaging and by chemical analysis. Transmission electron microscopy also makes possible the examination of reactions involving nitrate and ammonia in submicron individual particles. The proposed studies, taken together, will provide fine-scale data about a wide range of particle types that occur in the marine troposphere and that affect radiation backscatter and the microphysical properties of clouds.