Relations Between Ice Nuclei and Ice Formation in Clouds

摘要/大卫·C·罗杰斯/9714177冰核和云中冰形成的关系这项研究将研究大气中引发冰核形成的气溶胶粒子(Imon as Ice Ncore，或IN)与云中冰晶形成的关系。云中冰如何开始形成的问题是大气科学中一个长期存在的问题。在过去的40年里，在科学综述中指出了对这一主题进行研究的必要性。为此，人们利用仪器飞行器进行了许多野外研究，以研究云的结构和微物理。以前试图将冰云和冰晶浓度联系起来的尝试取决于在一个地点和时间进行的云观测，在不同地点和时间收集的气溶胶，以及稍后在实验室处理的气溶胶收集。在某些情况下，测量结果解决了温度依赖关系，但没有包括同样重要的湿度变化。这样的问题，再加上冰浓度的广泛自然变异性，使得评估冰核浓度与云中给定部分的冰晶浓度是否有很好的相关性变得困难。这项研究采用了一种新的方法来解决这个问题。现在有了一种新的仪器--快速响应的气载连续流动扩散室(CFD)，能够实时地同时观测气溶胶和云，并能够选择和调整IN测量的温度和湿度。冰核将在同一时间在同一架飞机上进行微物理观测。将确定IN浓度与温度和湿度的关系，并收集IN气溶胶进行电子显微镜检查，以确定尺寸和元素组成。这项工作包括在研究飞机上安装仪器，获得气溶胶加上云微物理和其他特性的测量，并在三年内进行分析和数值模拟。观测将在美国五大湖区冬季风暴以及科罗拉多州和怀俄明州地形波浪云的NSF支持的实地研究中进行。分析将包括将IN测量与飞机微物理数据进行比较。还将进行冰形成和云微物理的数值过程模拟，以帮助解释这些数据。将利用参与实地方案的其他研究人员收集的微物理和遥感观测，研究冬季风暴中初级冰核(与次级过程)和降水形成之间的关系。

Abstract/David C. Rogers/9714177 Relations between Ice Nuclei and Ice Formation in Clouds This research will examine the relationship between the aerosol particles in the atmosphere that initiate nucleation of ice (Imown as Ice Nuclei, or IN) and the formation of ice crystals in clouds The question of how ice begins to form in clouds is a long-standing problem in atmospheric science. The need for research on this topic has been pointed out in scientific reviews over the past 40 years. To this end, many field studies have been performed using instrumented aircraft to examine cloud stnucture and microphysics. Previous attempts to correlate Ice Nulclci and ice crystal concentrations oflen depended on cloud observations at one location and time, collecting aerosols at a different location and time, and processing the aerosol collections still later, at a laboratory. In some cases, measurements addressed temperature dependencies but did not include equally important variations in humidity. Problems such as this, together with the wide natural variability of ice concentrations, have made it difficult to evaluate whether concentrations of ice nuclei are well correlated with concentrations of ice crystals in a given part of a cloud. This research embraces a new approach to this question. Simultaneous observations of aerosols and clouds, in real time, with the capability to select and adjust the temperature and humidity of IN measurements are now possible with a new instrument, a fast-response airborne continuous flow difflision chamber (CFD). Ice nuclei will be measured at the same time and in the same aircraft making microphysical observations. The temperature and humidity dependence of IN concentration will be determined, and IN aerosols will be collected for electron microscope examination to determine size and elemental composition. The work involves installing instrumentation on research aircraft, obtaining measurements of aerosols plus cloud microphysical and other prope rties, and performing analyses and numerical modeling over a three-year period. Observations will be made in NSF-supported field studies ofwinter storms in the Great Lakes region of the U.S. and in orographic wave clouds in Colorado and Wyoming. The analyses will involve comparing IN measurements with aircraft microphysical data. Numerical process-modeling of ice formation and cloud microphysics will also be performed to aid the interpretation of these data. The relation between primary ice nucleation (versus secondary processes) and precipitation formation in winter storms will be investigated using microphysical and remote-sensing observations collected by other investigators who are participating in the field programs.