Cloud Condensation Nuclei (CCN) in Freezing Drizzle

这笔赠款支持Hudson博士参与AIRS II项目(第二联盟结冰研究)，这是一个由美国、加拿大和欧洲的机构和机构合作的项目，目的是解决飞机结冰的实际问题。AIRS实地计划计划于2003-04年冬季在加拿大蒙特利尔北部的米拉贝尔机场进行，地面观测网络和地面遥感设备将设在那里。哈德森博士和他的同事们将在俄亥俄州克利夫兰起飞的NSF C-130飞机上负责云微物理观测。主要的科学目标是解释过冷云区域可以形成并继续存在的情况，尽管也可能存在冰晶。C-130将装备用于测量云的水分和冰含量；冰晶的浓度、大小、习性和密度；形成冰的核的浓度；以及项目区内和云形成处上游空气中的气溶胶粒子的浓度和特征。哈德森博士将操作他的CCN(云凝聚核)光谱仪，以提供有关气溶胶粒子在感兴趣的云中和周围的成核能力的信息。人们的注意力将集中在过饱和度较低时活跃的大核上。这些颗粒迅速长大，大到足以促进合并和形成毛毛雨大小的水滴，这是飞机结冰的主要原因。CCN是导致从晴朗空气中的气溶胶到云滴的形成，再到冰晶或雨滴产生的一系列事件中的关键环节。这一研究不仅有助于从根本上理解过冷云中的微物理过程，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.