Cloud Condensation Nuclei (CCN) in Freezing Drizzle

这笔赠款支持哈德逊博士参加AIRS II项目（第二次联盟结冰研究），这是美国、加拿大和欧洲机构和机构的合作，目的是解决飞机结冰的实际问题。 AIRS的实地方案定于2003-04年冬季在加拿大蒙特利尔北部的米拉贝尔机场进行，那里将设有地面观测网络和地面遥感设备。 哈德逊博士和他的同事们将负责在俄亥俄州克利夫兰的NSF C-130飞机上进行云微物理观测。 主要的科学目标是解释过冷云区域形成并继续存在的环境，尽管冰晶也可能存在。 C-130将配备用于测量云的含水量和冰含量;冰晶的浓度、大小、习性和密度;冰形成核的浓度;以及项目区域内和云形成处上游空气中气溶胶颗粒的浓度和特性。 哈德逊博士将操作他的CCN（云凝结核）光谱仪，以提供有关气溶胶粒子在感兴趣的云层及其周围的成核能力的信息。 注意力将集中在在低过饱和度时活跃的大核上。 这些颗粒迅速增长到足够大的尺寸，以促进聚结和形成毛毛雨大小的水滴，这是飞机结冰的主要原因。 云凝结核是一系列事件中的关键环节，这些事件从晴朗空气中的气溶胶到云滴的形成，再到冰晶或雨滴的产生。 这项研究不仅有助于对过冷云微物理过程的基本理解，而且有助于提高航空安全。

This grant supports the participation of Dr. Hudson in the AIRS II project (second Alliance Icing Research Study), a collaboration of American, Canadian, and European agencies and institutions motivated by the practical problem of aircraft icing. The AIRS field program is scheduled for the winter of 2003-04 and based at Mirabel Airport, north of Montreal, Canada, where a surface observing network and ground-based remote-sensing equipment will be located. Dr. Hudson and his colleagues will be responsible for cloud microphysical observations aboard the NSF C-130 aircraft operating out of Cleveland, Ohio. The main scientific objective is to explain the circumstances by which regions of supercooled cloud can form and continue to exist though ice crystals may also be present. The C-130 will be equipped for measuring the water content and ice content of clouds; the concentration, size, habit, and density of ice crystals; the concentration of ice-forming nuclei; and the concentration and characteristics of aerosol particles both within the project area and in the air upstream of where the clouds form. Dr. Hudson will operate his CCN (cloud condensation nuclei) spectrometers to give information on the nucleating ability of aerosol particles in and around the clouds of interest. Attention will be focused on the large nuclei that are active at low values of supersaturation. These are the particles that quickly grow to sizes large enough to promote coalescence and the formation of drizzle-size drops, which are a major cause of aircraft icing. CCN are a critical link in the sequence of events leading from aerosols in the clear air, to the formation of cloud droplets, to the generation of either ice crystals or raindrops. The research contributes not only to the fundamental understanding of microphysical processes in supercooled clouds but also to the advancement of aviation safety.