Aircraft Studies of Charge-Enhanced Contact Ice Nucleation

首席研究人员正在进行必要的基本测量，以促进对导致云中冰晶形成的机制和条件的理解。大气科学尚未解决的主要问题之一是确定导致云中冰粒最初形成的物理过程。这项研究的知识价值在于，通过直接的实地测量，获得了云中冰生成的新关键数据。冰在云实验（ice）期间，利用国家科学基金会的设备获得了冰形成的重要数据。装有最先进的云物理仪器的飞机正在获取关于云的微物理特性的数据。首席研究人员正在使用他们独特的灵敏静电计来测量云滴和气溶胶颗粒所携带的平均电荷。他们正在调查自然产生的电荷如何增强云滴对气溶胶颗粒的清除作用，以及由此产生的接触是否会导致云滴冻结。电荷的数据是至关重要的，因为没有电荷引起的气溶胶和云滴之间的吸引力，接触是不可能的。主要研究人员所作的测量被用来评价导致初始冰形成的物理过程以及层云和积云中云滴接触冻结的速率。由于过冷云滴到冰的转化显著地改变了云的辐射特性，首席研究员研究的更广泛影响将导致云辐射计算的改进。应用包括从卫星数据中更好地检索云的特性，以及通过气候模型进行更准确的预测。除了研究云中结冰的重要性外，首席研究员的研究还将促进对云清除空气污染等相关学科的理解。该项目通过创造和利用新的仪器来解决大气科学中尚未解决的问题，从而促进科学基础设施的发展。

The Principal Investigators are making fundamental measurements needed for advancing understanding of the mechanisms and conditions that lead to the formation of ice crystals in clouds. One of the major unsolved issues in atmospheric science is the determination of the physical processes that lead to the initial formation of ice particles in clouds. The intellectual merit of this research is that new critical data on the generation of ice in clouds are being obtained by direct, in situ, measurements. Important data on ice formation are being obtained using facilities of the National Science Foundation during the Ice in Cloud Experiment (ICE). Data on the microphysical properties of clouds are being obtained by aircraft equipped with the most advanced cloud physics instruments. The Principal Investigators are using their unique sensitive electrometer to measure the average charge carried by cloud drops and aerosol particles. They are investigating how naturally occurring charges enhance the scavenging of aerosol particles by cloud drops and whether the resulting contact causes cloud drops to freeze. Data on charge are critical because without charge-induced attraction between aerosol and cloud drops contact is unlikely. The measurements made by the Principal Investigators are being used to evaluate the physical processes responsible for initial ice formation and the rates of contact-freezing of cloud drops in stratus and cumulus clouds.Because the conversion of supercooled cloud drops to ice significantly changes the cloud radiative properties, the broader impacts of the Principal Investigators' research will lead to improvements in cloud radiation calculations. Applications include better retrieval of cloud properties from satellite data and more accurate predictions by climate models. In addition to the importance of the research on ice formation in clouds, the Principal Investigators' research will advance understanding in related disciplines such as scavenging of air pollution by clouds. This project is contributing to the development of scientific infrastructure through the creation and utilization of new instrumentation to address unresolved problems in atmospheric science.