Cloud Condensation Nuclei (CCN) in Freezing Drizzle

这项资助支持哈德森博士参与AIRS II项目（第二联盟结冰研究），这是美国、加拿大和欧洲机构和机构的合作，受到飞机结冰实际问题的激励。AIRS实地项目计划在2003- 2004年冬季进行，基地设在加拿大蒙特利尔北部的Mirabel机场，地面观测网络和地面遥感设备将在那里部署。哈德森博士和他的同事们将在俄亥俄州克利夫兰的国家科学基金会C-130飞机上负责云的微物理观测。主要的科学目标是解释在冰晶可能存在的情况下，过冷云区域能够形成并继续存在的环境。C-130将配备测量云的含水量和冰含量的设备；冰晶：冰晶的浓度、大小、习性和密度；造冰核的浓度；以及项目区域内和云形成上游空气中的气溶胶颗粒的浓度和特征。哈德森博士将使用他的CCN（云凝结核）光谱仪来提供有关感兴趣的云内部和周围气溶胶粒子成核能力的信息。注意将集中在低过饱和度时活跃的大核。这些颗粒会迅速生长到足够大的尺寸，从而促进聚并形成细雨大小的水滴，这是飞机结冰的主要原因。从晴空中的气溶胶到云滴的形成，再到冰晶或雨滴的产生，CCN是一系列事件的关键环节。该研究不仅有助于从根本上了解过冷云的微物理过程，而且有助于提高航空安全水平。

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.