Individual-Particle Studies of Cloud Droplet Residues and Ambient Aerosols in RICO: Effects of Particle Size, Composition, Surface Properties and Mixing State on Trade-Wind Cumuli

该项目是将于2004年11月至2005年1月在安提瓜附近进行的一项名为“海洋积云中的雨”(RICO)的大型合作实验的一部分。RICO的一个主要目标是了解暖雨的形成，暖雨是在未达到冰点的云层中形成的雨。为了实现这一目标，这些研究人员将确定形成云和雨的空气中颗粒物的组成和浓度。大颗粒，大小在几微米到几十微米之间，被认为在从温暖的云层开始降雨方面发挥着特别重要的作用。研究人员将使用研究飞机收集此类颗粒的样本，并使用电子显微镜对其进行分析，以确定它们的大小、组成和浓度。他们将比较在云外收集的样本和通过蒸发云中的云滴获得的样本，以帮助确定粒子如何影响云滴的形成，以及当它们在云中时，液滴的内部成分是如何改变的。这项研究还将评估矿物粉尘颗粒、海盐颗粒以及含有元素碳和有机物种的颗粒的重要性。这些研究结果将被这些研究人员和RICO的其他人用来了解大型气溶胶粒子如何影响信风积云中降雨的形成。

This project is part of a larger collaborative experiment called "Rain in Cumulus over the Ocean" (RICO), which will be conducted from November 2004 to January 2005 near Antigua. A primary RICO objective is to understand warm-rain formation, the formation of rain in clouds that do not reach the freezing level. To contribute to that goal, these investigators will determine the composition and concentration of particles present in the air where clouds and rain form. Large particles, with sizes of a few to tens of micrometers, are thought to play an especially important role in the initiation of rainfall from warm clouds. Using a research aircraft, the investigators will collect samples of such particles and analyze them using electron microscopy to determine their sizes, composition, and concentration. They will compare samples collected outside cloud to those obtained by evaporation of cloud droplets in cloud to help determine how particles influence the formation of cloud droplets and how the internal composition of the drops is modified while they are in cloud. The study will also assess the importance of mineral-dust particles, sea-salt particles, and particles containing elemental carbon and organic species. The results will be used by these investigators and others in RICO to understand how large aerosol particles influence the formation of rain in trade-wind Cumulus clouds.