CAREER: Size Resolved Measurement of Cloud Condensation Nuclei Concentration and Properties

职业：云凝结核浓度和性质的尺寸分辨测量

• 批准号: 0094342
• 负责人: Don Collins
• 金额: $ 50.66万
• 依托单位: Texas A&M Research Foundation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-02-01 至 2006-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0094342&HistoricalAwards=false
• 关键词: CAREER; Size; Resolved; Measurement; Cloud

This grant supports the design and fabrication of a novel instrument for studying the atmospheric aerosols that serve as condensation nuclei for the formation of cloud droplets. The instrument consists of a differential mobility analyzer (DMA), which separates the aerosol particles into a narrow range of sizes, followed by a cloud condensation nucleus separator (CCNS), which separates the more hygroscopic particles from the less hygroscopic ones. It is the hygroscopic particles that can serve as condensation nuclei. The CCNS consists of two concentric cylinders, between which an electric field is applied. The annular region between the cylinders is basically a thermal gradient diffusion chamber. The inner and outer walls are maintained at different temperatures and at water saturation by means of wet filter paper, so that the space between them is supersaturated. The particles are charged when they leave the DMA, and the field applied to the CCNS causes them to migrate slowly towards the inner wall as they move with the air through the chamber. The electrical mobility of the particles is reduced as they grow by condensation. Hence the particles that grow large have less chance of migrating to the inner wall than those that remain small. From the initial population of near-equal sized particles that enter the CCNS, the less hygroscopic ones are thus deposited on the inner wall, and those that serve as CCN at the applied supersaturation pass through. The two-stage instrument therefore makes it possible to study the nucleating properties of aerosol particles in different size ranges. As a further step in the analysis, the chemical composition of the CCN that exit the instrument may be determined using a single-particle mass spectrometer. Results of the research are relevant to the basic physics of cloud formation and to the question of aerosol effects on the solar reflectivity of clouds.The educational component of this CAREER award consists of a summer course for undergraduate students on techniques, applications, and practical aspects of meteorological and atmospheric chemical measurements. The culmination of the course is a week-long field campaign in Marina, CA, centered on airborne observations with the research facilities of the Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS).

该赠款支持一种新型仪器的设计和制造，用于研究大气气溶胶，这些气溶胶是形成云滴的凝结核。 该仪器由差异迁移率分析仪（DMA）组成，该分析仪将气溶胶颗粒分离成狭窄的大小范围，然后是云凝结核分离核（CCN），将较弱的颗粒与较少的湿气颗粒分开。 可以用作凝结核的吸湿颗粒。 CCN由两个同心圆柱组成，在它们之间使用电场。 气缸之间的环形区域基本上是热梯度扩散室。 内壁和外壁通过湿滤纸保持在不同的温度和水饱和度处，以使它们之间的空间过饱和。 当颗粒离开DMA时，它们会充电，并且将场应用于CCN会导致它们在用空气通过腔室移动时缓慢地向内壁迁移。 颗粒的电迁移率随着凝结而生长而降低。 因此，生长大的颗粒比保持小的颗粒迁移到内壁的机会较小。 从进入CCN的近似粒子的初始群体中，较小的吸湿性颗粒被沉积在内壁上，而在应用过饱和度中充当CCN的颗粒则通过。 因此，两阶段的仪器可以研究不同尺寸范围内气溶胶颗粒的成核性能。作为分析的另一个一步，可以使用单粒子质谱仪确定退出仪器的CCN的化学组成。 该研究的结果与云形成的基本物理学以及气溶胶对云太阳反射率的影响有关。该职业奖的教育组成部分由夏季课程组成，适用于本科生在技术，应用程序以及气象和大气化学化学化学化学测量方面的实际方面。 该课程的高潮是在加利福尼亚州玛丽娜（Marina）进行的为期一周的野外运动，集中在跨学科远程试验的飞机研究中心（CIRPAS）的研究机构的空中观察中。